draft-ietf-mmusic-sdp-atm-02.txt   draft-ietf-mmusic-sdp-atm-03.txt 
Internet Engineering Task Force Internet Engineering Task Force
Internet Draft Rajesh Kumar Internet Draft Rajesh Kumar
Document: draft-ietf-mmusic-sdp-atm-02.txt Mohamed Mostafa Document: draft-ietf-mmusic-sdp-atm-03.txt Mohamed Mostafa
October 27, 2000 Cisco Systems December 18, 2000 Cisco Systems
Expires: April 27, 2001 Expires: June 18, 2001
Conventions for the use of the Session Description Protocol (SDP) Conventions for the use of the Session Description Protocol (SDP)
for ATM Bearer Connections for ATM Bearer Connections
STATUS OF THIS DOCUMENT STATUS OF THIS DOCUMENT
This document is an Internet-Draft and is in full conformance with This document is an Internet-Draft and is in full conformance with
all provisions of Section 10 of RFC2026. all provisions of Section 10 of RFC2026.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
skipping to change at line 42 skipping to change at line 42
Abstract Abstract
This document describes conventions for using the Session Description This document describes conventions for using the Session Description
Protocol (SDP) described in RFC2327 [1] for controlling ATM Bearer Protocol (SDP) described in RFC2327 [1] for controlling ATM Bearer
Connections, and any associated ATM Adaptation Layer (AAL). The AALs Connections, and any associated ATM Adaptation Layer (AAL). The AALs
addressed are Type 1, Type 2 and Type 5. This list of conventions is addressed are Type 1, Type 2 and Type 5. This list of conventions is
meant to be exhaustive. Individual applications can use subsets of meant to be exhaustive. Individual applications can use subsets of
these conventions. Further, these conventions are meant to comply these conventions. Further, these conventions are meant to comply
strictly with the SDP syntax as defined in rfc2327. strictly with the SDP syntax as defined in rfc2327.
1. Introduction...............................................................2 1. Introduction...............................................................3
2. Representation of Certain Fields within SDP description lines..............4 2. Representation of Certain Fields within SDP description lines..............4
2.2 Representation of Parameter Values.....................................4 2.1 Representation of Extension Attributes.................................4
2.3 Directionality Convention..............................................4 2.2 Representation of Parameter Values.....................................5
2.4 Case convention.........................................................5 2.3 Directionality Convention..............................................5
2.5 Use of special characters in SDP parameter values.......................5 2.4 Case convention.........................................................6
3. Capabilities Provided by SDP conventions..................................6 2.5 Use of special characters in SDP parameter values.......................6
4. Format of the ATM Session Description......................................7
5.1 The Origin Line.........................................................8
5.2 The Session Name Line...................................................9
5.3 The Connection Information Line.........................................9
5.4 The Timestamp Line.....................................................11
5.5 Media Information Line for ATM connections.............................11
5.5.1 The Virtual Connection ID.........................................12
5.5.2 The Transport Parameter...........................................14
5.5.3 The Format List for AAL1 and AAL5 applications....................15
5.5.4 The Format List for AAL2 applications.............................15
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5.5.5 Media information line construction...............................16
5.6 The Media Attribute Lines..............................................18 3. Capabilities Provided by SDP conventions..................................7
5.6.1 The 'atmmap' attribute.......................................21 4. Format of the ATM Session Description......................................8
5.6.2 The 'eecid' attribute............................................25 5. Structure of the Session Description Lines...............................10
5.6.3 The 'aalType' attribute............................................26 5.1 The Origin Line........................................................10
5.6.4 The 'silenceSupp' attribute........................................26 5.2 The Session Name Line..................................................11
5.6.5 The 'ecanf' and 'ecanb' attributes.................................27 5.3 The Connection Information Line........................................11
5.6.6 The 'gcf' and 'gcb' attributes.....................................28 5.4 The Timestamp Line.....................................................13
5.6.7 The 'profileDesc' attribute........................................29 5.5 Media Information Line for ATM connections.............................14
5.6.8 The 'vsel' attribute...............................................30 5.5.1 The Virtual Connection ID.........................................14
5.6.9 The 'dsel' attribute...............................................31 5.5.2 The Transport Parameter...........................................16
5.6.10 The 'fsel' attribute..............................................32 5.5.3 The Format List for AAL1 and AAL5 applications....................18
5.6.11 The 'capability' attribute.......................................33 5.5.4 The Format List for AAL2 applications.............................18
5.6.12 The 'qosClass' attribute.........................................34 5.5.5 Media information line construction...............................18
5.6.13 The 'bcob' attribute.............................................34 5.6 The Media Attribute Lines..............................................23
5.6.14 The 'stc' attribute..............................................35 5.6.1 The 'atmmap' attribute.......................................27
5.6.15 The 'upcc' attribute.............................................35 5.6.2 The 'eecid' attribute............................................30
5.6.16 The 'atmQOSfparms' and 'atmQOSbparms' attributes..................35 5.6.3 The 'aalType' attribute............................................32
5.6.17 The 'aal2QOSfparms' and 'aal2QOSbparms' attributes...............36 5.6.4 The 'silenceSupp' attribute........................................32
5.6.18 The 'atmFtrfcDesc' and 'atmBtrfcDesc' attributes..................36 5.6.5 The 'ecanf' and 'ecanb' attributes.................................34
5.6.19 The 'aal2FtrfcDesc' and 'aal2BtrfcDesc' attributes...............38 5.6.6 The 'gcf' and 'gcb' attributes.....................................35
5.6.20 The 'abrFparms' and 'abrBparms' attributes.......................38 5.6.7 The 'profileDesc' attribute........................................35
5.6.21 The 'clkrec' attribute............................................39 5.6.8 The 'vsel' attribute...............................................37
5.6.23 The 'prtfl' attribute.............................................40 5.6.9 The 'dsel' attribute...............................................38
5.6.24 The 'bearerType' attribute........................................40 5.6.10 The 'fsel' attribute..............................................39
5.6.25 The 'structure' attribute.........................................41 5.6.11 The 'codecconfig' attribute......................................41
5.6.26 The 'sbc' attribute...............................................41 5.6.12 The 'isup_usi' attribute.........................................41
5.6.27 The 'fcpsSDUsize' and 'bcpsSDUsize' attributes....................41 5.6.13 The 'capability' attribute.......................................42
5.6.28 The 'aal2CPS' attribute...........................................42 5.6.14 The 'qosClass' attribute.........................................43
5.6.29 The 'aal2sscs3661' attribute......................................42 5.6.15 The 'bcob' attribute.............................................43
5.6.30 The 'aal2sscs3662' attribute......................................43 5.6.16 The 'stc' attribute..............................................44
5.6.31 The 'aalApp' attribute............................................44 5.6.17 The 'upcc' attribute.............................................44
5.6.32 The 'lij' attribute...............................................45 5.6.18 The 'atmQOSfparms' and 'atmQOSbparms' attributes..................44
5.6.34 The 'cache' attribute.............................................46 5.6.19 The 'atmFtrfcDesc' and 'atmBtrfcDesc' attributes..................46
5.6.35 Specification of Higher-layer attributes......................47 5.6.20 The 'abrFparms' and 'abrBparms' attributes.......................48
5.6.36 Use of the second media-level part in H.323 Annex C applications47 5.6.21 The 'clkrec' attribute............................................49
5.6.37 Chaining SDP descriptors........................................48 5.6.22 The 'fec' attribute...............................................49
5.6.38 Use of the eecid media attribute in call establishment procedures48 5.6.23 The 'prtfl' attribute.............................................50
6.0 List of Parameters with Representations...............................52 5.6.24 The 'bearerType' attribute........................................50
7.0 Examples of ATM session descriptions using SDP.........................58 5.6.25 The 'structure' attribute.........................................51
8.0 Representation of data media..........................................59 5.6.26 The 'sbc' attribute...............................................51
9.0 Security Considerations..................................................60 5.6.27 The 'fcpsSDUsize' and 'bcpsSDUsize' attributes....................52
9.1 Bearer Security.......................................................60 5.6.28 The 'aal2CPS' attribute...........................................53
9.2 Security of the SDP description.......................................60 5.6.29 The 'aal2sscs3661unassured' attribute.............................54
10. ATM SDP Grammar..........................................................61 5.6.30 The 'aal2sscs3661assured' attribute...............................54
5.6.31 The 'aal5sscop' attribute.........................................56
5.6.32 The 'aal2sscs3662' attribute......................................56
5.6.33 The 'aalApp' attribute............................................58
5.6.34 The 'lij' attribute...............................................60
5.6.35 The 'anycast' attribute...........................................60
5.6.36 The 'cache' attribute.............................................61
5.6.37 Specification of Higher-layer attributes..........................61
5.6.38 Use of the second media-level part in H.323 Annex C applications..62
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5.6.39 Chaining SDP descriptors..........................................63
5.6.40 Use of the eecid media attribute in call establishment procedures.63
6.0 List of Parameters with Representations...............................68
7.0 Examples of ATM session descriptions using SDP.........................76
8.0 Security Considerations..................................................77
8.1 Bearer Security.......................................................77
8.2 Security of the SDP description.......................................77
9.0 ATM SDP Grammar.........................................................78
1. Introduction 1. Introduction
SDP will be used in conjunction with a connection handling /device SDP will be used in conjunction with a connection handling /device
control protocol such as Megaco (H.248) [26], SIP [18] or MGCP [25] to control protocol such as Megaco (H.248) [26], SIP [18] or MGCP [25] to
communicate the information needed to set up ATM and AAL2 bearer communicate the information needed to set up ATM and AAL2 bearer
connections. These connections include voice connections, voiceband data connections. These connections include voice connections, voiceband data
connections, clear channel circuit emulation connections, video connections connections, clear channel circuit emulation connections, video connections
and baseband data connections (such as fax relay, modem relay, SSCOP, and baseband data connections (such as fax relay, modem relay, SSCOP,
frame relay etc.). frame relay etc.).
These conventions use standard SDP syntax as defined in rfc2327 These conventions use standard SDP syntax as defined in rfc2327
to describe the ATM-level and AAL-level connections, addresses and to describe the ATM-level and AAL-level connections, addresses and
other parameters. In general, parameters associated with layers other parameters. In general, parameters associated with layers
higher than the ATM adaptation layer are included only if they are higher than the ATM adaptation layer are included only if they are
tightly coupled to the ATM or AAL layers. Since the syntax conforms to tightly coupled to the ATM or AAL layers. Since the syntax conforms to
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rfc2327, standard SDP parsers should react in a well-defined and safe rfc2327, standard SDP parsers should react in a well-defined and safe
manner on receiving session descriptions based on the SDP conventions manner on receiving session descriptions based on the SDP conventions
in this document. This is done by extending the values of fields defined in in this document. This is done by extending the values of fields defined in
rfc2327 rather than by defining new fields. This is true for all SDP lines rfc2327 rather than by defining new fields. This is true for all SDP lines
except the of the media attribute lines, in which case new except the of the media attribute lines, in which case new
attributes are defined. The SDP protocol allows the definition attributes are defined. The SDP protocol allows the definition
of new attributes in the media attribute lines which are free-form. of new attributes in the media attribute lines which are free-form.
For the remaining lines, the fact that the <networkType> field in For the remaining lines, the fact that the <networkType> field in
an SDP descriptor is set to "ATM" should preclude the misinterpretation of an SDP descriptor is set to "ATM" should preclude the misinterpretation of
extended parameter values by rfc2327-compliant SDP parsers. extended parameter values by rfc2327-compliant SDP parsers.
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to service connections. These resources could be: to service connections. These resources could be:
* AAL1/AAL5 PVCs, SPVCs or cached SVCs, * AAL1/AAL5 PVCs, SPVCs or cached SVCs,
* AAL2 single-CID PVCs, SPVCs or cached SVCs, * AAL2 single-CID PVCs, SPVCs or cached SVCs,
* CIDs within AAL2 SVCs/PVCs/SPVCs that multiplex multiple * CIDs within AAL2 SVCs/PVCs/SPVCs that multiplex multiple
CIDs. CIDs.
Note that the difference between PVCs and SPVCs is in the way the bearer Note that the difference between PVCs and SPVCs is in the way the bearer
virtual circuit connection is set up. SPVCs are a class of PVCs that use virtual circuit connection is set up. SPVCs are a class of PVCs that use
bearer signaling, as opposed to node-by-node provisioning, for connection bearer signaling, as opposed to node-by-node provisioning, for connection
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establishment. establishment.
This document is limited to the case when the network type is ATM. This document is limited to the case when the network type is ATM.
This includes raw RTP encapsulation [45] or voice sample encapsulation This includes raw RTP encapsulation [45] or voice sample encapsulation
[46] over AAL5 with no intervening IP layer. It does not address SDP usage [46] over AAL5 with no intervening IP layer. It does not address SDP usage
for IP, with or without ATM as a lower layer. for IP, with or without ATM as a lower layer.
In some cases, IP connection set-up is independent of lower layers, which In some cases, IP connection set-up is independent of lower layers, which
are configured prior to it. For example, AAL5 PVCs that connect IP routers are configured prior to it. For example, AAL5 PVCs that connect IP routers
can be used for VoIP calls. In other cases, VoIP call set-up is closely can be used for VoIP calls. In other cases, VoIP call set-up is closely
tied to ATM-level connection set-up. This might require a chaining of IP and tied to ATM-level connection set-up. This might require a chaining of IP and
ATM descriptors, as described in section 5.6.37. ATM descriptors, as described in section 5.6.39.
This document makes no assumptions on who constructs the session This document makes no assumptions on who constructs the session
descriptions (media gateway, intermediate ATM/AAL2 switch, media descriptions (media gateway, intermediate ATM/AAL2 switch, media
gateway controller etc.). This will be different in different gateway controller etc.). This will be different in different
applications. Further, it allows the use of one session description applications. Further, it allows the use of one session description
for both directions of a connection (as in SIP and MGCP applications) for both directions of a connection (as in SIP and MGCP applications)
or the use of separate session descriptions for different directions. It or the use of separate session descriptions for different directions. It
also addresses the ATM multicast and anycast capabilities. also addresses the ATM multicast and anycast capabilities.
This document makes no assumptions about how the SDP description will This document makes no assumptions about how the SDP description will
be coded. Although the descriptions shown here are encoded as text, be coded. Although the descriptions shown here are encoded as text,
alternate codings are possible: alternate codings are possible:
- Binary encoding such as ASN.1. This is an option (in addition to - Binary encoding such as ASN.1. This is an option (in addition to
text encoding) in the Megaco context. text encoding) in the Megaco context.
- Use of extended ISUP parameters [36] to encode the information in - Use of extended ISUP parameters [36] to encode the information in
SDP descriptors, with conversion to/from binary/text-based SDP SDP descriptors, with conversion to/from binary/text-based SDP
encoding when needed. encoding when needed.
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2. Representation of Certain Fields within SDP description lines 2. Representation of Certain Fields within SDP description lines
This document conforms to the syntactic conventions of standard SDP as This document conforms to the syntactic conventions of standard SDP as
defined in RFC2327 [1]. defined in RFC2327 [1].
2.1 Representation of Extension Attributes 2.1 Representation of Extension Attributes
The SDP protocol [1] requires that non-standard attributes and codec The SDP protocol [1] requires that non-standard attributes and codec
names use an "X-" prefix. names use an "X-" prefix.
In this internet draft, the "X-" prefix is used consistently for In this internet draft, the "X-" prefix is used consistently for
codec names (Table 2) that have not been registered with IANA [31]. codec names (Table 2) that have not been registered with the IANA.
The IANA-registered codec names listed in [31] do not
use this prefix, regardless of whether they are statically or
dynamically assigned payload types.
However, this prefix is not used for the extension SDP attributes However, this prefix is not used for the extension SDP attributes
defined in this document. This has been done to enhance legibility. defined in this document. This has been done to enhance legibility.
This document suggests that parsers be flexible in the use of the This document suggests that parsers be flexible in the use of the
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"X-" prefix convention. They should accept codec names and attribute "X-" prefix convention. They should accept codec names and attribute
names with or without the "X-" prefix. names with or without the "X-" prefix.
2.2 Representation of Parameter Values 2.2 Representation of Parameter Values
Depending on the format of their representation in SDP, the Depending on the format of their representation in SDP, the
parameters defined in this document fall into the following parameters defined in this document fall into the following
classes: classes:
(1) Parameters always represented in a decimal format. (1) Parameters always represented in a decimal format.
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Generally, leading 0 digits are not used in either hexadecimal or decimal Generally, leading 0 digits are not used in either hexadecimal or decimal
representations. Exceptions are when an exact number of hex digits representations. Exceptions are when an exact number of hex digits
is expected, as in the case of NSAP addresses. Parsers shall not is expected, as in the case of NSAP addresses. Parsers shall not
reject leading zeros in hex values. reject leading zeros in hex values.
Both single-character and multi-character string values are enclosed in Both single-character and multi-character string values are enclosed in
double quotes (i.e. "). By contrast, single quotes (i.e. ') are used for double quotes (i.e. "). By contrast, single quotes (i.e. ') are used for
emphasizing keywords rather than to refer to characters or strings. emphasizing keywords rather than to refer to characters or strings.
In the text representation of decimal and hex numbers, digits to the
left are more significant than digits to the right.
2.3 Directionality Convention 2.3 Directionality Convention
This section defined the meaning of the terms 'forward' and This section defined the meaning of the terms 'forward' and
'backward' as used in this document. This is specially applicable 'backward' as used in this document. This is specially applicable
to parameters that have a specific direction associated with them. to parameters that have a specific direction associated with them.
In this document, 'forward' refers to the direction away from the In this document, 'forward' refers to the direction away from the
ATM node under consideration, while 'backward' refers to the direction ATM node under consideration, while 'backward' refers to the direction
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towards the ATM node. This convention must be used in all SDP-based towards the ATM node. This convention must be used in all SDP-based
session descriptions regardless of whether underlying bearer is an SVC, a session descriptions regardless of whether underlying bearer is an SVC, a
dynamically allocated PVC/SPVC or a dynamically allocated CID. This dynamically allocated PVC/SPVC or a dynamically allocated CID. This
is regardless of which side originates the service connection. If ATM is regardless of which side originates the service connection. If ATM
SVC or AAL2 Q.2630.1 signaling is used, the directionality convention SVC or AAL2 Q.2630.1 signaling is used, the directionality convention
is independent of which side originates the SVC or AAL2 connection. is independent of which side originates the SVC or AAL2 connection.
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This provides a simple way of identifying the direction in which a This provides a simple way of identifying the direction in which a
parameter is applicable, in a manner that is independent of the parameter is applicable, in a manner that is independent of the
underlying ATM or AAL2 bearer. This simplicity comes at a price, underlying ATM or AAL2 bearer. This simplicity comes at a price,
described below. described below.
The convention used by all ATM/AAL2 signaling specifications (e.g. Q.2931 The convention used by all ATM/AAL2 signaling specifications (e.g. Q.2931
Section 1.3.3 and Q.2630.1) mandates that forward direction is from the Section 1.3.3 and Q.2630.1) mandates that forward direction is from the
end initiating setup/establishment via bearer signaling towards the end end initiating setup/establishment via bearer signaling towards the end
receiving the setup/establishment request. The backward direction is in receiving the setup/establishment request. The backward direction is in
the opposite direction. In some cases, the 'forward' and 'backward' the opposite direction. In some cases, the 'forward' and 'backward'
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String values used in SDP descriptions of ATM connections retain this String values used in SDP descriptions of ATM connections retain this
convention, while allowing the use of the special character "/" in a manner convention, while allowing the use of the special character "/" in a manner
commensurate with [1]. In addition, the special characters "$" and "-" are commensurate with [1]. In addition, the special characters "$" and "-" are
used in the following manner. A "$" value is a wildcard that allows the used in the following manner. A "$" value is a wildcard that allows the
recipient of the SDP description to select any permitted value of the recipient of the SDP description to select any permitted value of the
parameter. A "-" value indicates that it is not necessary to specify the parameter. A "-" value indicates that it is not necessary to specify the
value of the parameter in the SDP description because this parameter is value of the parameter in the SDP description because this parameter is
irrelevant for this application, or because its value can be irrelevant for this application, or because its value can be
known from another source such as provisioning, defaults, another known from another source such as provisioning, defaults, another
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protocol, another SDP descriptor or another part of the same SDP protocol, another SDP descriptor or another part of the same SDP
descriptor. If the use of these special characters is construed as a descriptor. If the use of these special characters is construed as a
violation of rfc2327 [1] syntax, then reserved string values can be used. violation of rfc2327 [1] syntax, then reserved string values can be used.
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The string "CHOOSE" can be used in lieu of "$". The string "OMIT" can be The string "CHOOSE" can be used in lieu of "$". The string "OMIT" can be
used in lieu of "-" for an omitted parameter. A decision to use special used in lieu of "-" for an omitted parameter. A decision to use special
characters or reserved keywords will be made before this internet draft characters or reserved keywords will be made before this internet draft
is upgraded to an rfc. is upgraded to an rfc.
3. Capabilities Provided by SDP conventions 3. Capabilities Provided by SDP conventions
To support these applications listed in section 1, the SDP conventions in To support the applications listed in section 1, the SDP conventions in
this document provide the following session control capabilities: this document provide the following session control capabilities:
* Identification of the underlying bearer network type as ATM. * Identification of the underlying bearer network type as ATM.
* Identification by an ATM network element of its own address, * Identification by an ATM network element of its own address,
in one of several possible formats. A connection peer can in one of several possible formats. A connection peer can
initiate SVC set-up to this address. A call agent or connection initiate SVC set-up to this address. A call agent or connection
peer can select an pre-established bearer path to this address. peer can select an pre-established bearer path to this address.
* Identification of the ATM bearer connection that is to be * Identification of the ATM bearer connection that is to be
bound to the service-level connection. This is either bound to the service-level connection. This is either
a VCC in AAL1/AAL2/AAL5 applications or a channel (identified by a VCC in AAL1/AAL2/AAL5 applications or a channel (identified by
a CID) in AAL2 applications. a CID) in AAL2 applications.
* Identification of media type: audio, video, data. * Identification of media type: audio, video, data.
* In AAL1/AAL5 applications, declaration of a set of payload * In AAL1/AAL5 applications, declaration of a set of payload
types that can be bound to the ATM bearer connection. types that can be bound to the ATM bearer connection.
RTP payload types that have been registered with IANA are The encoding names and payload types defined for use in
re-used for AAL1 or AAL5 [31]. In the manner of standard SDP, the RTP context [31] are re-used for AAL1 and AAL5,
unregistered payload types are mapped dynamically. if applicable.
* In AAL2 applications, declaration of a set of profiles that * In AAL2 applications, declaration of a set of profiles that
can be bound to the ATM bearer connection. A mechanism for can be bound to the ATM bearer connection. A mechanism for
dynamically defining custom profiles within the SDP session dynamically defining custom profiles within the SDP session
description is included. This allows the use of custom description is included. This allows the use of custom
profiles for connections that span multi-network interfaces. profiles for connections that span multi-network interfaces.
* A means of correlating service-level connections with * A means of correlating service-level connections with
underlying ATM bearer connections. The backbone network underlying ATM bearer connections. The backbone network
connection identifier or bnc-id specified in ITU Q.1901 [36] connection identifier or bnc-id specified in ITU Q.1901 [36]
standardization work is used for this purpose. In order to standardization work is used for this purpose. In order to
provide a common SDP base for applications based on provide a common SDP base for applications based on
Q.1901 and SIP/SIP+, the neutral term 'eecid' is used Q.1901 and SIP/SIP+, the neutral term 'eecid' is used
in lieu of 'bnc-id' in the SDP session descriptor. in lieu of 'bnc-id' in the SDP session descriptor.
* A means of mapping codec types and packetization periods into * A means of mapping codec types and packetization periods into
service types (voice, voiceband data and facsimile). This is service types (voice, voiceband data and facsimile). This is
useful in determining the encoding to use when the connection is useful in determining the encoding to use when the connection is
upspeeded in response to modem or facsimile tones. upspeeded in response to modem or facsimile tones.
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* A means of describing the adaptation type, QoS class, ATM transfer * A means of describing the adaptation type, QoS class, ATM transfer
capability/service category, broadband bearer class, traffic capability/service category, broadband bearer class, traffic
parameters, CPS parameters and SSCS parameters related the underlying parameters, CPS parameters and SSCS parameters related the underlying
bearer connection. bearer connection.
* Means for enabling or describing special functions such as leaf- * Means for enabling or describing special functions such as leaf-
initiated-join, anycast and SVC caching. initiated-join, anycast and SVC caching.
* For H.323 Annex C applications, a means of specifying the IP address * For H.323 Annex C applications, a means of specifying the IP address
and port number on which the node will receive RTCP messages. and port number on which the node will receive RTCP messages.
* A means of chaining consecutive SDP descriptors so that they refer to * A means of chaining consecutive SDP descriptors so that they refer to
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different layers of the same connection. different layers of the same connection.
4. Format of the ATM Session Description 4. Format of the ATM Session Description
The sequence of lines in the session descriptions in this document The sequence of lines in the session descriptions in this document
conforms to rfc2327 [1]. In general, a session description consists of conforms to rfc2327 [1]. In general, a session description consists of
a session-level part followed by zero or more media-level parts. ATM a session-level part followed by zero or more media-level parts. ATM
session descriptions consist of a session-level part followed by one session descriptions consist of a session-level part followed by one
or two media-level parts. The only two media applicable are the ATM or two media-level parts. The only two media applicable are the ATM
bearer medium and RTCP control (where applicable). bearer medium and RTCP control (where applicable).
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k= (encryption key, zero or more lines) k= (encryption key, zero or more lines)
a= (media attribute, zero or more lines) a= (media attribute, zero or more lines)
The media level part for RTCP control consists of the following The media level part for RTCP control consists of the following
lines: lines:
m= (media information and transport address, one line) m= (media information and transport address, one line)
c= (connection information for control only, one line) c= (connection information for control only, one line)
In general, the 'v', 'o', 's', and 't' lines are mandatory. In general, the 'v', 'o', 's', and 't' lines are mandatory.
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However, in the Megaco [26] context, these lines have been made optional. However, in the Megaco [26] context, these lines have been made optional.
The 'o', 's', and 't' lines are omitted in most MGCP [25] applications. The 'o', 's', and 't' lines are omitted in most MGCP [25] applications.
Note that SDP session descriptors for ATM can contain bandwidth (b=) and Note that SDP session descriptors for ATM can contain bandwidth (b=) and
encryption key (k=) lines. Like all other lines, these lines should encryption key (k=) lines. Like all other lines, these lines should
strictly conform to the SDP standard [1]. strictly conform to the SDP standard [1].
The bandwidth (b=) line is not necessarily redundant in the ATM context The bandwidth (b=) line is not necessarily redundant in the ATM context
since, in some applications, it can be used to convey application-level since, in some applications, it can be used to convey application-level
information which does not map directly into the atmFtrfcDesc and information which does not map directly into the atmFtrfcDesc and
skipping to change at line 434 skipping to change at line 448
in SDP descriptors in RTSP commands to describe content bandwidth. in SDP descriptors in RTSP commands to describe content bandwidth.
The encryption key line (k=) can be used The encryption key line (k=) can be used
to indicate an encryption key for the bearer, and a method to to indicate an encryption key for the bearer, and a method to
obtain the key. At present, the encryption of ATM and AAL2 bearers obtain the key. At present, the encryption of ATM and AAL2 bearers
has not been conventionalized, unlike the encryption of RTP payloads. has not been conventionalized, unlike the encryption of RTP payloads.
Nor has the authentication or encryption of ATM or AAL2 bearer signaling. Nor has the authentication or encryption of ATM or AAL2 bearer signaling.
In the ATM and AAL2 contexts, the term 'bearer' can include 'bearer In the ATM and AAL2 contexts, the term 'bearer' can include 'bearer
signaling' as well as 'bearer payloads'. signaling' as well as 'bearer payloads'.
Rajesh Kumar, Mohamed Mostafa. 7
The order of lines in an ATM session description is exactly in the The order of lines in an ATM session description is exactly in the
rfc2327-conformant order depicted above. However, there is no order rfc2327-conformant order depicted above. However, there is no order
of the media attribute ('a') lines with respect to other 'a' lines. of the media attribute ('a') lines with respect to other 'a' lines.
The SDP protocol version for session descriptions using these The SDP protocol version for session descriptions using these
conventions is 0. In conformance with standard SDP, it is strongly conventions is 0. In conformance with standard SDP, it is strongly
recommended that the 'v' line be included at the beginning of each recommended that the 'v' line be included at the beginning of each
SDP session description. In some contexts such as Megaco, the SDP session description. In some contexts such as Megaco, the
'v' line is optional and may be omitted unless several session 'v' line is optional and may be omitted unless several session
descriptions are provided in sequence, in which case the descriptions are provided in sequence, in which case the
'v' line serves as a delimiter. Depending on the application, 'v' line serves as a delimiter. Depending on the application,
sequences of session descriptions might refer to: sequences of session descriptions might refer to:
- Different connections or sessions. - Different connections or sessions.
- Alternate ways of realizing the same connection or session. - Alternate ways of realizing the same connection or session.
- Different layers of the same session (section 5.6.37). - Different layers of the same session (section 5.6.39).
The 'o', 's' and 't' lines are included for strict conformance with The 'o', 's' and 't' lines are included for strict conformance with
RFC2327. It is possible that these lines might not carry useful RFC2327. It is possible that these lines might not carry useful
information in some ATM-based applications. information in some ATM-based applications.
Therefore, some applications might omit these lines, although Therefore, some applications might omit these lines, although
it is recommended that they not do so. For maximum it is recommended that they not do so. For maximum
interoperability, it is preferable that SDP parsers not interoperability, it is preferable that SDP parsers not
reject session descriptions that do not contain these lines. reject session descriptions that do not contain these lines.
Rajesh Kumar, Mohamed Mostafa. 9
5. Structure of the Session Description Lines 5. Structure of the Session Description Lines
5.1 The Origin Line 5.1 The Origin Line
The origin line for an ATM-based session is structured as follows: The origin line for an ATM-based session is structured as follows:
o=<username> <sessionID> <version> <networkType> o=<username> <sessionID> <version> <networkType>
<addressType> <address> <addressType> <address>
The <username> is set to "-". The <username> is set to "-".
skipping to change at line 495 skipping to change at line 510
The <sessionID> field is represented as a decimal or hex number of The <sessionID> field is represented as a decimal or hex number of
up to 32 digits. A "0x" prefix is used before the hex representation. up to 32 digits. A "0x" prefix is used before the hex representation.
The <version> refers to the version of the SDP session descriptor The <version> refers to the version of the SDP session descriptor
(not that of the SDP protocol). This is can be set to one of the (not that of the SDP protocol). This is can be set to one of the
following: following:
* 0. * 0.
* an NTP timestamp referring to the moment when the SDP session * an NTP timestamp referring to the moment when the SDP session
Rajesh Kumar, Mohamed Mostafa. 8
descriptor was modified. If the SDP session descriptor has not descriptor was modified. If the SDP session descriptor has not
been modified by an intermediate entity (such as an MGC), been modified by an intermediate entity (such as an MGC),
then the <version> timestamp will be the same as the <sessionId> then the <version> timestamp will be the same as the <sessionId>
timestamp, if any. As with the <sessionId>, only the integer part timestamp, if any. As with the <sessionId>, only the integer part
of the NTP timestamp is used. of the NTP timestamp is used.
When equated to the integer part of an NTP timestamp, the <version> field When equated to the integer part of an NTP timestamp, the <version> field
is 10 digits wide. This is more restricted than [1], which allows unlimited is 10 digits wide. This is more restricted than [1], which allows unlimited
size. As in [1], the most significant digit is non-zero when an NTP size. As in [1], the most significant digit is non-zero when an NTP
timestamp is used. timestamp is used.
The <networkType> in SDP session descriptions for ATM applications The <networkType> in SDP session descriptions for ATM applications
should be assigned the string value "ATM" or wildcarded to a "$" or "-". should be assigned the string value "ATM" or wildcarded to a "$" or "-".
The <addressType> and <address> parameters are identical to The <addressType> and <address> parameters are identical to
those for the connection information ('c') line (Section 5.3). Each of those for the connection information ('c') line (Section 5.3). Each of
Rajesh Kumar, Mohamed Mostafa. 10
these parameters can be wildcarded per the conventions described these parameters can be wildcarded per the conventions described
for the 'c' line in Section 5.3. These parameters should not me omitted for the 'c' line in Section 5.3. These parameters should not me omitted
since this would violate SDP syntax [1]. since this would violate SDP syntax [1].
As with the 'c' line, SDP parsers are not expected to check the consistency As with the 'c' line, SDP parsers are not expected to check the consistency
of <networkType> with <addressType>, <address> pairs. The <addressType> of <networkType> with <addressType>, <address> pairs. The <addressType>
and <address> need to be consistent with each other. and <address> need to be consistent with each other.
5.2 The Session Name Line 5.2 The Session Name Line
skipping to change at line 540 skipping to change at line 555
s=- s=-
5.3 The Connection Information Line 5.3 The Connection Information Line
In general, the connection information line [1] is structured as follows: In general, the connection information line [1] is structured as follows:
c=<networkType> <addressType> <address> c=<networkType> <addressType> <address>
For ATM networks, additional values of <networkType>, <addressType> For ATM networks, additional values of <networkType>, <addressType>
and <address> are defined, over and above those listed in [1]. The and <address> are defined, over and above those listed in [1]. The
ABNF syntax (Section 10) for ATM SDP does not limit the ways in which ABNF syntax (Section 9) for ATM SDP does not limit the ways in which
<networkType> can be combined with <addressType>, <address> pairs. <networkType> can be combined with <addressType>, <address> pairs.
However, some combinations will not be valid in However, some combinations will not be valid in
certain applications, while others will never be valid. Invalid certain applications, while others will never be valid. Invalid
combinations should be rejected by application-specific functions, and combinations should be rejected by application-specific functions, and
not by generic parsers. The ABNF syntax does limit the ways in which not by generic parsers. The ABNF syntax does limit the ways in which
<addressType> and <address> can be paired. <addressType> and <address> can be paired.
For ATM networks, the value of <networkType> should be set to "ATM". For ATM networks, the value of <networkType> should be set to "ATM".
Further, this may be wildcarded to "$" or "-". If this is done, an Further, this may be wildcarded to "$" or "-". If this is done, an
node using ATM as the basic transport mechanism will select a node using ATM as the basic transport mechanism will select a
value of "ATM". A node that interfaces with multiple network types value of "ATM". A node that interfaces with multiple network types
("IN", "ATM" etc.) that include ATM can also choose a value of "ATM". ("IN", "ATM" etc.) that include ATM can also choose a value of "ATM".
When the SDP description is built by a node such as a media gateway, When the SDP description is built by a node such as a media gateway,
the <address> refers to the address of the node building the SDP the <address> refers to the address of the node building the SDP
description. When this description is forwarded to another node, it still description. When this description is forwarded to another node, it still
Rajesh Kumar, Mohamed Mostafa. 9
contains the original node's address. When the media gateway contains the original node's address. When the media gateway
controller builds part or all of the SDP description, the local descriptor controller builds part or all of the SDP description, the local descriptor
can contain the address of the local node, while the can contain the address of the local node, while the
remote descriptor can contain the address of the remote node. remote descriptor can contain the address of the remote node.
If the <address> and/or <addressType> are irrelevant or are If the <address> and/or <addressType> are irrelevant or are
known by other means, they can be wildcarded per the conventions known by other means, they can be wildcarded per the conventions
described below. described below.
Rajesh Kumar, Mohamed Mostafa. 11
Additionally, in all contexts, the 'm' line can have an ATM address in the Additionally, in all contexts, the 'm' line can have an ATM address in the
<virtualConnectionId> subparameter which, if present, is the <virtualConnectionId> subparameter which, if present, is the
remote address if the 'c' line address is local, and vice versa. remote address if the 'c' line address is local, and vice versa.
For ATM networks, the <addressType> can be NSAP, E164 or GWID (ALIAS). For ATM networks, the <addressType> can be NSAP, E164 or GWID (ALIAS).
For ATM networks, the <address> syntax depends on the syntax of For ATM networks, the <address> syntax depends on the syntax of
the <addressType>. SDP parsers should check the consistency the <addressType>. SDP parsers should check the consistency
of <addressType> with <address>. of <addressType> with <address>.
NSAP: If the addressType is NSAP, the address is expressed in NSAP: If the addressType is NSAP, the address is expressed in
the standard dotted hex form. This is a string of 40 hex digits, the standard dotted hex form. This is a string of 40 hex digits,
with dots after the 2nd, 6th, 10th, 14th, 18th, 22nd, 26th, 30th, with dots after the 2nd, 6th, 10th, 14th, 18th, 22nd, 26th, 30th,
34th and 38th digits. The last octet of the NSAP address is the 34th and 38th digits. The last octet of the NSAP address is the
'selector' field that is available for non-standard use. An example 'selector' field that is available for non-standard use. An example
of a śc∆ line with an NSAP address is: of a 'c' line with an NSAP address is:
c=ATM NSAP 47.0091.8100.0000.0060.3e64.fd01.0060.3e64.fd01.00 c=ATM NSAP 47.0091.8100.0000.0060.3e64.fd01.0060.3e64.fd01.00
A "0x" prefix shall not be used in this case since this is always in A "0x" prefix shall not be used in this case since this is always in
hexadecimal format. hexadecimal format.
E164: If the addressType is E164, the address is expressed as E164: If the addressType is E164, the address is expressed as
a decimal number with up to 15 digits. For example: a decimal number with up to 15 digits. For example:
c=ATM E164 9738294382 c=ATM E164 9738294382
skipping to change at line 617 skipping to change at line 631
("A"-"Z", "a"-"z", "0" - "9",".","-","_"). For example: ("A"-"Z", "a"-"z", "0" - "9",".","-","_"). For example:
c=ATM GWID officeABCmgx101vism12 c=ATM GWID officeABCmgx101vism12
Since these SDP conventions can be used for more than gateways, the Since these SDP conventions can be used for more than gateways, the
string "ALIAS" can be used instead of "GWID" in the 'c' line. Thus, string "ALIAS" can be used instead of "GWID" in the 'c' line. Thus,
the example above is equivalent to: the example above is equivalent to:
c=ATM ALIAS officeABCmgx101vism12 c=ATM ALIAS officeABCmgx101vism12
Rajesh Kumar, Mohamed Mostafa. 12
An example of a GWID (ALIAS)is the CLLI code used for telecom An example of a GWID (ALIAS)is the CLLI code used for telecom
equipment. For all practical purposes, it should be adequate for the equipment. For all practical purposes, it should be adequate for the
Rajesh Kumar, Mohamed Mostafa. 10
GWID (ALIAS) to be a variable length string with a maximum size of 32 GWID (ALIAS) to be a variable length string with a maximum size of 32
characters. characters.
The connection information line is always present in an SDP session The connection information line is always present in an SDP session
descriptor. However, each of the parameters on this line can be wildcarded descriptor. However, each of the parameters on this line can be wildcarded
to a "$" or a "-", independently of whether other parameters on this line to a "$" or a "-", independently of whether other parameters on this line
are wildcarded or not. Not all syntactically legal wildcard combinations are wildcarded or not. Not all syntactically legal wildcard combinations
are meaningful in a particular application. are meaningful in a particular application.
Examples of meaningful wildcard combinations in the ATM context are: Examples of meaningful wildcard combinations in the ATM context are:
skipping to change at line 670 skipping to change at line 683
follows: follows:
t= <startTime> <stopTime> t= <startTime> <stopTime>
Per Ref. [49], NTP time stamps use a 32 bit unsigned Per Ref. [49], NTP time stamps use a 32 bit unsigned
representation of seconds, and a 32 bit unsigned representation of representation of seconds, and a 32 bit unsigned representation of
fractional seconds. For ATM-based sessions, the <startTime>parameter can fractional seconds. For ATM-based sessions, the <startTime>parameter can
be made equal to the NTP timestamp referring to the moment when be made equal to the NTP timestamp referring to the moment when
the SDP session descriptor was created. It can also be set to 0 the SDP session descriptor was created. It can also be set to 0
indicating its irrelevance. If it made equal to the NTP indicating its irrelevance. If it made equal to the NTP
Rajesh Kumar, Mohamed Mostafa. 13
timestamp in seconds, the fractional part of the NTP timestamp is omitted. timestamp in seconds, the fractional part of the NTP timestamp is omitted.
When equated to the integer part of an NTP timestamp, the <startTime> When equated to the integer part of an NTP timestamp, the <startTime>
field is 10 digits wide. This is more restricted than [1], which field is 10 digits wide. This is more restricted than [1], which
allows unlimited size. As in [1], the most significant digit is allows unlimited size. As in [1], the most significant digit is
non-zero when an NTP timestamp is used. non-zero when an NTP timestamp is used.
The <stopTime> parameter is set to 0 for ATM-based SDP descriptors. The <stopTime> parameter is set to 0 for ATM-based SDP descriptors.
5.5 Media Information Line for ATM connections 5.5 Media Information Line for ATM connections
The general format of the media information line adapted for AAL1 The general format of the media information line adapted for AAL1
Rajesh Kumar, Mohamed Mostafa. 11
and AAL5 applications is: and AAL5 applications is:
m=<media> <virtualConnectionId> <transport> <format list> m=<media> <virtualConnectionId> <transport> <format list>
The general format of the media information line adapted for AAL2 The general format of the media information line adapted for AAL2
applications is: applications is:
m=<media> <virtualConnectionId> <transport#1> <format list#1> m=<media> <virtualConnectionId> <transport#1> <format list#1>
<transport#2> <format list#2> ... <transport#M> <format list#M> <transport#2> <format list#2> ... <transport#M> <format list#M>
skipping to change at line 724 skipping to change at line 737
* <addressType>-<address>/<ex_vpci>/<ex_vci> * <addressType>-<address>/<ex_vpci>/<ex_vci>
* <address>/<ex_vpci>/<ex_vci> * <address>/<ex_vpci>/<ex_vci>
The <virtualConnectionId> in AAL2 applications can be in one of the The <virtualConnectionId> in AAL2 applications can be in one of the
following formats: following formats:
* <ex_vcci>/<ex_cid> * <ex_vcci>/<ex_cid>
* <addressType>-<address>/<ex_vcci>/<ex_cid> * <addressType>-<address>/<ex_vcci>/<ex_cid>
* <address>/<ex_vcci>/<ex_cid> * <address>/<ex_vcci>/<ex_cid>
* <ex_bcg>/<ex_vcci>/<ex_cid> * <ex_bcg>/<ex_vcci>/<ex_cid>
Rajesh Kumar, Mohamed Mostafa. 14
* <ex_portId>/<ex_vpi>/<ex_vci>/<ex_cid> * <ex_portId>/<ex_vpi>/<ex_vci>/<ex_cid>
* <ex_bcg>/<ex_vpi>/<ex_vci>/<ex_cid> * <ex_bcg>/<ex_vpi>/<ex_vci>/<ex_cid>
* <ex_vpci>/<ex_vci>/<ex_cid> * <ex_vpci>/<ex_vci>/<ex_cid>
* <addressType>-<address>/<ex_vpci>/<ex_vci>/<ex_cid> * <addressType>-<address>/<ex_vpci>/<ex_vci>/<ex_cid>
* <address>/<ex_vpci>/<ex_vci>/<ex_cid> * <address>/<ex_vpci>/<ex_vci>/<ex_cid>
Here, Here,
<ex_vcci> = VCCI-<vcci> <ex_vcci> = VCCI-<vcci>
<ex_vpci> = VPCI-<vpci> <ex_vpci> = VPCI-<vpci>
<ex_bcg> = BCG-<bcg> <ex_bcg> = BCG-<bcg>
<ex_portId> = PORT-<portId> <ex_portId> = PORT-<portId>
<ex_vpi> = VPI-<vpi> <ex_vpi> = VPI-<vpi>
<ex_vci> = VCI-<vci> <ex_vci> = VCI-<vci>
<ex_cid> = CID-<cid> <ex_cid> = CID-<cid>
The <vcci>, <vpi>, <vci>, <vpci> and <cid> are decimal numbers The <vcci>, <vpi>, <vci>, <vpci> and <cid> are decimal numbers
or hexadecimal numbers. An "0x" prefix is used before their values or hexadecimal numbers. An "0x" prefix is used before their values
when they are in the hex format. when they are in the hex format.
The <portId> is always a hexadecimal number. An "0x" prefix is not used The <portId> is always a hexadecimal number. An "0x" prefix is not used
Rajesh Kumar, Mohamed Mostafa. 12
with it. with it.
The <addressType> and <address> are identical The <addressType> and <address> are identical
to their definitions above for the connection information line with to their definitions above for the connection information line with
the difference that this address refers to the remote peer in the the difference that this address refers to the remote peer in the
media information line. Since the <virtualConnectionId>, as defined media information line. Since the <virtualConnectionId>, as defined
here, is meant for use in ATM networks, the values of <addressType> here, is meant for use in ATM networks, the values of <addressType>
and <address> in the <virtualConnectionId> are limited to ATM-specific and <address> in the <virtualConnectionId> are limited to ATM-specific
values. values.
skipping to change at line 778 skipping to change at line 791
The <vcci> is similar to the <vci>, except for the fact that it retains The <vcci> is similar to the <vci>, except for the fact that it retains
its value across VC crossconnects. its value across VC crossconnects.
Since <vpci> and <vcci> values are unique between a pair of nodes, they Since <vpci> and <vcci> values are unique between a pair of nodes, they
need to be qualified, at any node, by the ATM address of the remote node. need to be qualified, at any node, by the ATM address of the remote node.
These parameters can be pre-provisioned or signaled. When signaled, the These parameters can be pre-provisioned or signaled. When signaled, the
<vpci> is encapsulated in the connection identifier information element of <vpci> is encapsulated in the connection identifier information element of
SVC signaling messages. The <vcci> is encapsulated in the Generic SVC signaling messages. The <vcci> is encapsulated in the Generic
Information Transport (GIT) information element of SVC signaling messages. Information Transport (GIT) information element of SVC signaling messages.
In an ATM node pair, either node can assign <vcci> values and signal it to In an ATM node pair, either node can assign <vcci> values and signal it to
Rajesh Kumar, Mohamed Mostafa. 15
the other end via SVC signaling. A glare avoidance scheme is defined in [32] the other end via SVC signaling. A glare avoidance scheme is defined in [32]
and [44].This mechanism works in SVC applications. A different glare and [44].This mechanism works in SVC applications. A different glare
avoidance technique is needed when a pool of existing PVCs/SPVCs is avoidance technique is needed when a pool of existing PVCs/SPVCs is
dynamically assigned to calls. One such scheme for glare reduction is the dynamically assigned to calls. One such scheme for glare reduction is the
assignment of <vcci> values from different ends of the <vcci> range, using assignment of <vcci> values from different ends of the <vcci> range, using
the lowest or highest available value as applicable. the lowest or highest available value as applicable.
When <vpci> and <vcci> values are pre-provisioned, administrations have the When <vpci> and <vcci> values are pre-provisioned, administrations have the
option of provisioning them uniquely in a network or in a subnet. In this option of provisioning them uniquely in a network or in a subnet. In this
case, the ATM address of the far end is not needed to qualify these case, the ATM address of the far end is not needed to qualify these
skipping to change at line 807 skipping to change at line 822
The <portId> parameter is used to identify the physical trunk port The <portId> parameter is used to identify the physical trunk port
on an ATM module. It can be represented as a hexadecimal number of on an ATM module. It can be represented as a hexadecimal number of
up to 32 hex digits. up to 32 hex digits.
In some applications, it is meaningful to bundle a set of connections In some applications, it is meaningful to bundle a set of connections
between a pair of ATM nodes into a bearer connection group. The <bcg> between a pair of ATM nodes into a bearer connection group. The <bcg>
subparameter is an eight bit field that allows the bundling of up subparameter is an eight bit field that allows the bundling of up
to 255 VPCs or VCCs. to 255 VPCs or VCCs.
In some applications, it is necessary to wildcard the <virtualConnectionId> In some applications, it is necessary to wildcard the <virtualConnectionId>
Rajesh Kumar, Mohamed Mostafa. 13
parameter, or some elements of this parameter. The "$" wildcard character parameter, or some elements of this parameter. The "$" wildcard character
can be substituted for the entire <virtualConnectionId> parameter, or some can be substituted for the entire <virtualConnectionId> parameter, or some
of its terms. In the latter case, the constant strings that of its terms. In the latter case, the constant strings that
qualify the terms in the <virtualConnectionId> are retained. The qualify the terms in the <virtualConnectionId> are retained. The
concatenation <addressType>-<address> can be wildcarded in the concatenation <addressType>-<address> can be wildcarded in the
following ways: following ways:
* The entire concatenation, <addressType>-<address>, is * The entire concatenation, <addressType>-<address>, is
replaced with a "$". replaced with a "$".
* <address> is replaced with a "$", but <addressType> is * <address> is replaced with a "$", but <addressType> is
not. not.
skipping to change at line 832 skipping to change at line 845
wildcarding the <virtualConnectionId> in the AAL2 context are: $, wildcarding the <virtualConnectionId> in the AAL2 context are: $,
VCCI-40/CID-$, BCG-100/VPI-20/VCI-120/CID-$, NSAP-$/VCCI-$/CID-$, VCCI-40/CID-$, BCG-100/VPI-20/VCI-120/CID-$, NSAP-$/VCCI-$/CID-$,
$/VCCI-$/CID-$. $/VCCI-$/CID-$.
It is also permissible to set the entire <virtualConnectionId> parameter It is also permissible to set the entire <virtualConnectionId> parameter
to a "-" indicating its irrelevance. to a "-" indicating its irrelevance.
5.5.2 The Transport Parameter 5.5.2 The Transport Parameter
The <transport> parameter indicates the method used to encapsulate the The <transport> parameter indicates the method used to encapsulate the
Rajesh Kumar, Mohamed Mostafa. 16
service payload. These methods are not defined in this document, which service payload. These methods are not defined in this document, which
refers to existing ATMF and ITU-T standards, which, in turn, might refers to existing ATMF and ITU-T standards, which, in turn, might
refer to other standards. For ATM applications, the following refer to other standards. For ATM applications, the following
<transport> values are defined: <transport> values are defined:
Table 1: List of Transport Parameter values used in SDP in the ATM context Table 1: List of Transport Parameter values used in SDP in the ATM context
+---------------------------------------------------------------------+ +---------------------------------------------------------------------+
| | Controlling Document for | | | Controlling Document for |
| Transport | Encapsulation of Service Payload | | Transport | Encapsulation of Service Payload |
+------------------------+--------------------------------------------+ +------------------------+--------------------------------------------+
skipping to change at line 870 skipping to change at line 885
| AAL2/<corporateName> | | | AAL2/<corporateName> | |
| AAL5/<corporateName> | | | AAL5/<corporateName> | |
| AAL1/IEEE:<oui> | Corporate document | | AAL1/IEEE:<oui> | Corporate document |
| AAL2/IEEE:<oui> | | | AAL2/IEEE:<oui> | |
| AAL5/IEEE:<oui> | | | AAL5/IEEE:<oui> | |
+------------------------+--------------------------------------------+ +------------------------+--------------------------------------------+
| RTP/AVP | Annex C of H.323 [45] | | RTP/AVP | Annex C of H.323 [45] |
+------------------------+--------------------------------------------+ +------------------------+--------------------------------------------+
In H.323 Annex C applications [45], the <transport> parameter has a In H.323 Annex C applications [45], the <transport> parameter has a
Rajesh Kumar, Mohamed Mostafa. 14
value of "RTP/AVP". This is because these applications use the RTP value of "RTP/AVP". This is because these applications use the RTP
protocol [2] and audio/video profile [3]. The fact that RTP is carried protocol [2] and audio/video profile [3]. The fact that RTP is carried
directly over AAL5 per [45] can be indicated explicitly via the aalApp directly over AAL5 per [45] can be indicated explicitly via the aalApp
media attribute. media attribute.
A value of "AAL1/custom", "AAL2/custom" or "AAL5/custom" for the A value of "AAL1/custom", "AAL2/custom" or "AAL5/custom" for the
<transport> parameter can indicate non-standard or semi-standard <transport> parameter can indicate non-standard or semi-standard
encapsulation schemes defined by a corporation or a multi-vendor encapsulation schemes defined by a corporation or a multi-vendor
agreement. Since there is no standard administration of this agreement. Since there is no standard administration of this
convention, care should be taken to preclude inconsistencies convention, care should be taken to preclude inconsistencies
within the scope of a deployment. within the scope of a deployment.
The use of <transport> values "AAL1/<corporateName>", The use of <transport> values "AAL1/<corporateName>",
"AAL2/<corporateName>", "AAL5/<corporateName>", "AAL1/IEEE:<oui>", "AAL2/<corporateName>", "AAL5/<corporateName>", "AAL1/IEEE:<oui>",
Rajesh Kumar, Mohamed Mostafa. 17
"AAL2/IEEE:<oui>" and "AAL5/IEEE:<oui>" is similar. These indicate "AAL2/IEEE:<oui>" and "AAL5/IEEE:<oui>" is similar. These indicate
non-standard transport mechanisms or AAL2 profiles which should non-standard transport mechanisms or AAL2 profiles which should
be used consistently within the scope of an application or deployment. be used consistently within the scope of an application or deployment.
The parameter <corporateName> is the registered, globally unique name The parameter <corporateName> is the registered, globally unique name
of a corporation(e.g. Cisco, Telcordia etc.). The parameter <oui> of a corporation(e.g. Cisco, Telcordia etc.). The parameter <oui>
is the hex representation of a three-octet field identical to the OUI is the hex representation of a three-octet field identical to the OUI
maintained by the IEEE. Since this is always represented in hex, the "0x" maintained by the IEEE. Since this is always represented in hex, the "0x"
prefix shall not be used. For example, "IEEE:00000C" is one of the prefix shall not be used. For example, "IEEE:00000C" is one of the
<oui> values that refers to Cisco Systems, Inc. <oui> values that refers to Cisco Systems, Inc.
skipping to change at line 908 skipping to change at line 923
In the AAL1 and AAL5 contexts, the <format list> is a list of payload In the AAL1 and AAL5 contexts, the <format list> is a list of payload
types: types:
<payloadType#1> <payloadType#2>...<payloadType#n> <payloadType#1> <payloadType#2>...<payloadType#n>
In most AAL1 and AAL5 applications, the ordering of payload types In most AAL1 and AAL5 applications, the ordering of payload types
implies a preference (preferred payload types before less favored implies a preference (preferred payload types before less favored
ones). The payload type can be statically assigned or dynamically ones). The payload type can be statically assigned or dynamically
mapped. Although the transport is not the same, SDP in the ATM mapped. Although the transport is not the same, SDP in the ATM
context leverages the encoding names and payload types registered context leverages the encoding names and payload types registered
with IANA [31] for RTP. These are the statically assigned payload with IANA [31] for RTP. Encoding names not listed in [31] use a "X-"
types. Encodings that are not statically mapped to payload types by prefix. Encodings that are not statically mapped to payload types in
IANA are to be dynamically mapped at the time of connection establishment [31] are to be dynamically mapped at the time of connection
to payload types in the decimal range 96-127. The SDP 'atmmap' establishment to payload types in the decimal range 96-127.
attribute (similar to 'rtpmap') is used for this purpose. Table 2 The SDP 'atmmap' attribute (similar to 'rtpmap') is used for this
lists a few key standard encoding names with their corresponding purpose.
statically assigned payload types from Ref. 31. It also suggests
encoding names for some other key codecs not addressed in [31]. For In addition to listing the IANA-registered encoding names and
these, payload types are mapped dynamically via the 'atmmap' attribute. payload types found in [31], Table 2 defines a few
These lists of statically assigned and dynamically mapped codec non-standard encoding names(with "X-" prefixes).
names are not meant to be exhaustive. Ref. 31 should be considered
the exhaustive list of statically assigned payload types.
5.5.4 The Format List for AAL2 applications 5.5.4 The Format List for AAL2 applications
In the AAL2 context, the <format list> is a list of AAL2 profile In the AAL2 context, the <format list> is a list of AAL2 profile
types: types:
<profile#1> <profile#2>...<profile#n> <profile#1> <profile#2>...<profile#n>
In most applications, the ordering of profiles implies In most applications, the ordering of profiles implies
a preference (preferred profiles before less favored ones). a preference (preferred profiles before less favored ones).
The <profile> parameter is expressed as a decimal number in the The <profile> parameter is expressed as a decimal number in the
range 1-255. range 1-255.
Rajesh Kumar, Mohamed Mostafa. 15
5.5.5 Media information line construction 5.5.5 Media information line construction
Using the parameter definitions above, the 'm' for AAL1-based audio Using the parameter definitions above, the 'm' for AAL1-based audio
media can be constructed as follows: media can be constructed as follows:
m=audio <virtualConnectionId> AAL1/ATMF <payloadType#1> m=audio <virtualConnectionId> AAL1/ATMF <payloadType#1>
<payloadType#2>...<payloadType #n> <payloadType#2>...<payloadType #n>
Rajesh Kumar, Mohamed Mostafa. 18
Note that only those payload types, whether statically mapped or Note that only those payload types, whether statically mapped or
dynamically assigned, that are consistent with af-vtoa-78 [7] can be used dynamically assigned, that are consistent with af-vtoa-78 [7] can be used
in this construction. in this construction.
Backwards compatibility note: The transport value "AAL1/AVP" used in Backwards compatibility note: The transport value "AAL1/AVP" used in
previous versions of this document should be considered equivalent to previous versions of this document should be considered equivalent to
the value "AAL1/ATMF" defined above. "AAL1/AVP" is unsuitable because the value "AAL1/ATMF" defined above. "AAL1/AVP" is unsuitable because
the AVP profile is closely tied to RTP. the AVP profile is closely tied to RTP.
An example 'm' line use for audio media over AAL1 is: An example 'm' line use for audio media over AAL1 is:
skipping to change at line 991 skipping to change at line 1003
context. The audio media on this VCC is encapsulated according to ITU-T context. The audio media on this VCC is encapsulated according to ITU-T
H.222.1 [51]. The encodings to be used are either ITU-T G.722 or ITU-T H.222.1 [51]. The encodings to be used are either ITU-T G.722 or ITU-T
G.728 (LD-CELP), in preferential order. G.728 (LD-CELP), in preferential order.
The 'm' for AAL5-based H.323 Annex C audio [45] can be constructed as The 'm' for AAL5-based H.323 Annex C audio [45] can be constructed as
follows: follows:
m=audio <virtualConnectionId> RTP/AVP <payloadType#1> m=audio <virtualConnectionId> RTP/AVP <payloadType#1>
<payloadType#2>...<payloadType #n> <payloadType#2>...<payloadType #n>
Rajesh Kumar, Mohamed Mostafa. 19
For example: For example:
m=audio PORT-9/VPI-3/VCI-$ RTP/AVP 2 96 m=audio PORT-9/VPI-3/VCI-$ RTP/AVP 2 96
a=rtpmap:96 X-G727-32 a=rtpmap:96 X-G727-32
Rajesh Kumar, Mohamed Mostafa. 16
a=aalType:AAL5 a=aalType:AAL5
a=aalApp:h323c a=aalApp:itu_h323c
implies that any VCI on VPI= 3 of trunk port #9 may be used. This VC implies that any VCI on VPI= 3 of trunk port #9 may be used. This VC
encapsulates RTP packets directly on AAL5 per [45]. The 'rtpmap' (rather encapsulates RTP packets directly on AAL5 per [45]. The 'rtpmap' (rather
than the 'atmmap') attribute is used to dynamically map the payload type than the 'atmmap') attribute is used to dynamically map the payload type
of 96 into the codec name X-G727-32 (Table 2). This name represents 32 of 96 into the codec name X-G727-32 (Table 2). This name represents 32
kbps EADPCM. kbps EADPCM.
The 'm' for AAL5-based video media can be constructed as follows: The 'm' line for AAL5-based video media can be constructed as follows:
m=video <virtualConnectionId> AAL5/ITU <payloadType#1> m=video <virtualConnectionId> AAL5/ITU <payloadType#1>
<payloadType#2>...<payloadType #n> <payloadType#2>...<payloadType #n>
In this case, the use of AAL5/ITU as the transport points to H.222.1 In this case, the use of AAL5/ITU as the transport points to H.222.1
as the controlling standard [51].An example 'm' line use for video media as the controlling standard [51].An example 'm' line use for video media
is: is:
m=video PORT-9/VPI-3/VCI-$ AAL5/ITU 33 m=video PORT-9/VPI-3/VCI-$ AAL5/ITU 33
This indicates that any VCI on VPI= 3 of trunk port #9 may be used. This indicates that any VCI on VPI= 3 of trunk port #9 may be used.
The video media on this VCC is encapsulated according to ITU-T The video media on this VCC is encapsulated according to ITU-T
H.222.1 [51]. The encoding scheme is an MPEG 2 transport stream ("MP2T" H.222.1 [51]. The encoding scheme is an MPEG 2 transport stream ("MP2T"
in Table 1). This is statically mapped per [31] to a payload type of 33. in Table 1). This is statically mapped per [31] to a payload type of 33.
The media information line for AAL5-based sessions with a "data" media
type has the following format:
m=data <virtualConnectionId> - -
In this case, the adaptation type is known from the aalType attribute
rather than the 'm' line. For example:
m=data PORT-7/VPI-6/VCI-$ - -
a=aalType:AAL5
a=aalApp:assuredSSCOP
implies that any VCI on VPI= 6 of trunk port #7 may be used. This VC
uses assured SSCOP on AAL5 to transport data.
Using the parameter definitions in the previous subsections, the media Using the parameter definitions in the previous subsections, the media
information line for AAL2-based audio media can be constructed as follows: information line for AAL2-based audio media can be constructed as follows:
m=<media> <virtualConnectionId> <transport#1> <format list#1> m=<media> <virtualConnectionId> <transport#1> <format list#1>
<transport#2> <format list#2> ... <transport#M> <format list#M> <transport#2> <format list#2> ... <transport#M> <format list#M>
where <format list#i> has the form <profile#i_1>...<profile#i_N> where <format list#i> has the form <profile#i_1>...<profile#i_N>
Unlike the 'm' line for AAL1 or AAL5 applications, the 'm' line for AAL2 Unlike the 'm' line for AAL1 or AAL5 applications, the 'm' line for AAL2
applications can have multiple <transport> parameters, each followed by applications can have multiple <transport> parameters, each followed by
a <format list>. This is because it is possible to consider definitions a <format list>. This is because it is possible to consider definitions
from multiple sources (ATMF, ITU and non-standard documents) when selecting from multiple sources (ATMF, ITU and non-standard documents) when selecting
AAL2 profile to be bound to a connection. AAL2 profile to be bound to a connection.
In most applications, the ordering of profiles implies a preference In most applications, the ordering of profiles implies a preference
(preferred profiles before less favored ones). Therefore, there can be (preferred profiles before less favored ones). Therefore, there can be
multiple instances of the same <transport> value in the same 'm' line. multiple instances of the same <transport> value in the same 'm' line.
An example 'm' line use for audio media over AAL2 is: An example 'm' line use for audio media over AAL2 is:
Rajesh Kumar, Mohamed Mostafa. 17
m=audio VCCI-27/CID-19 AAL2/ITU 7 AAL2/custom 100 AAL2/ITU 1 m=audio VCCI-27/CID-19 AAL2/ITU 7 AAL2/custom 100 AAL2/ITU 1
Rajesh Kumar, Mohamed Mostafa. 20
This indicates the use of CID #19 on VCCI #27 to carry audio. It provides This indicates the use of CID #19 on VCCI #27 to carry audio. It provides
a preferential list of profiles for this connection: profile AAL2/ITU 7 a preferential list of profiles for this connection: profile AAL2/ITU 7
defined in [13], AAL2/custom 100 defined in an application-specific or defined in [13], AAL2/custom 100 defined in an application-specific or
interoperability document and profile AAL2/ITU 1 defined in [13]. interoperability document and profile AAL2/ITU 1 defined in [13].
Another example of the use of the 'm' line use for audio media over AAL2 Another example of the use of the 'm' line use for audio media over AAL2
is: is:
m=audio VCCI-$/CID-$ AAL2/ATMF 6 8 m=audio VCCI-$/CID-$ AAL2/ATMF 6 8
skipping to change at line 1113 skipping to change at line 1109
m=audio VCCI-123/CID-5 - - m=audio VCCI-123/CID-5 - -
a=aalType:AAL2 a=aalType:AAL2
a=aal2sscs3662:audio off off on off on off off off - - - a=aal2sscs3662:audio off off on off on off off off - - -
Besides indicating an audio medium, a VCCI of 123 and a CID of 5, Besides indicating an audio medium, a VCCI of 123 and a CID of 5,
the 'm' line indicates an unspecified profile. The media attribute lines the 'm' line indicates an unspecified profile. The media attribute lines
indicate an adaptation layer of AAL2, and the use of the audio SAP [13] indicate an adaptation layer of AAL2, and the use of the audio SAP [13]
to carry demodulated facsimile. to carry demodulated facsimile.
Rajesh Kumar, Mohamed Mostafa. 21
The media information line for "data" media has one of the following
the following formats:
m=data <virtualConnectionId> - -
m=data - - -
The data could be circuit emulation data carried over AAL1 or AAL2,
or packet data carried over AAL5. Media attribute lines, rather than
the 'm' line, are used to indicate the adaptation type for the data
media. Examples of the representation of data media are listed below.
m=data PORT-7/VPI-6/VCI-$ - -
a=aalApp:AAL5_SSCOP
implies that any VCI on VPI= 6 of trunk port #7 may be used. This VC
uses SSCOP on AAL5 to transport data.
m=data PORT-7/VPI-6/VCI-50 - -
a=aalType:AAL1_SDT
a=sbc:6
implies that VCI 50 on VPI 6 on port 7 uses structured AAL1 to transfer
6 x 64 kbps circuit emulation data. This may be alternately represented
as:
m=data PORT-7/VPI-6/VCI-50 - -
b=AS:384
a=aalType:AAL1_SDT
The following lines:
m=data VCCI-123/CID-5 - -
a=aalType:AAL2
a=sbc:2
imply that CID 5 of VCCI 123 is used to transfer 2 x 64 kbps
circuit emulation data.
In the AAL1 context, it is also permissible to represent circuit
mode data as an "audio" codec. If this is done, the codec types used
are X-CCD or X-CCD-CAS. These encoding names are dynamically
mapped into payload types through the 'atmmap' attribute. For example:
m=audio VCCI-27 AAL1/AVP 98
a=atmmap:98 X-CCD
a=sbc:6
implies that AAL1 VCCI=27 is used for 6 x 64 transmission.
In the AAL2 context, the X-CCD codec can be assigned a profile
type and number. Even though it is not possible to construct
Rajesh Kumar, Mohamed Mostafa. 22
a profile table as described in ITU I.366.2 for this "codec",
it is preferable to adopt the common AAL2 profile convention in its
case. An example AAL2 profile mapping for the X-CCD codec could
be as follows:
PROFILE TYPE PROFILE NUMBER "CODEC" (ONLY ONE)
"custom" 200 X-CCD
The profile does not identify the number of subchannels ('n' in nx64).
This is known by other means such as the 'sbc' media attribute line.
For example, the media information line:
m=audio $ AAL2/custom 200
a=sbc:6
implies 384 kbps circuit emulation using AAL2 adaptation.
It is not necessary to define a profile with the X-CCD-CAS codec, since
this method of CAS transport [7] is not used in AAL2 applications.
5.6 The Media Attribute Lines 5.6 The Media Attribute Lines
In an SDP line sequence, the media information line 'm' is In an SDP line sequence, the media information line 'm' is
followed by one or more media attribute or 'a' lines. Media followed by one or more media attribute or 'a' lines. Media
attribute lines are per the format below: attribute lines are per the format below:
Rajesh Kumar, Mohamed Mostafa. 18
a=<attribute>:<value> a=<attribute>:<value>
or or
a=<value> a=<value>
In general, media attribute lines are optional except when needed to In general, media attribute lines are optional except when needed to
qualify the media information line. This qualification is necessary qualify the media information line. This qualification is necessary
when the "m" line for an AAL1 or AAL5 session specifies a payload when the "m" line for an AAL1 or AAL5 session specifies a payload
type that needs to be dynamically mapped. The 'atmmap' media type that needs to be dynamically mapped. The 'atmmap' media
skipping to change at line 1145 skipping to change at line 1214
cases, a media attribute line with all parameters set to "-" carries cases, a media attribute line with all parameters set to "-" carries
no information and should be preferably omitted. In other cases, no information and should be preferably omitted. In other cases,
such as the 'lij' media attribute line, the very presence of the such as the 'lij' media attribute line, the very presence of the
media attribute line conveys meaning. media attribute line conveys meaning.
There are no restrictions placed by rfc2327 [1] regarding the order There are no restrictions placed by rfc2327 [1] regarding the order
of 'a' lines with respect to other 'a' lines. However, these lines of 'a' lines with respect to other 'a' lines. However, these lines
must not contradict each other or the other SDP lines. Inconsistencies must not contradict each other or the other SDP lines. Inconsistencies
are not to be ignored and should be flagged as errors. Repeated media are not to be ignored and should be flagged as errors. Repeated media
attribute lines can carry additional information. These should not attribute lines can carry additional information. These should not
Rajesh Kumar, Mohamed Mostafa. 23
be inconsistent with each other. be inconsistent with each other.
Applications will selectively use the optional media attribute Applications will selectively use the optional media attribute
lines listed below. This is meant to be an exhaustive list for lines listed below. This is meant to be an exhaustive list for
describing the general attributes of ATM bearer networks. describing the general attributes of ATM bearer networks.
The following is a summary list of the SDP media attributes that can The following is a summary list of the SDP media attributes that can
be used in the ATM context. Detailed descriptions of these attributes be used in the ATM context. Detailed descriptions of these attributes
are to be found in subsequent sections. are to be found in subsequent sections.
skipping to change at line 1181 skipping to change at line 1252
In the Q.1901 [36] context, the eecid is synonymous with the In the Q.1901 [36] context, the eecid is synonymous with the
bnc-id (backbone network connection identifier). bnc-id (backbone network connection identifier).
* The 'aalType' attribute. This is used to indicate the nature * The 'aalType' attribute. This is used to indicate the nature
of the ATM adaptation layer (AAL). of the ATM adaptation layer (AAL).
* The 'silenceSupp' attribute, used to indicate the use of * The 'silenceSupp' attribute, used to indicate the use of
of voice activity detection for silence suppression, and to of voice activity detection for silence suppression, and to
optionally parameterize the silence suppression function. optionally parameterize the silence suppression function.
* The 'ecanf' and 'ecanb' attributes, used to indicate the use of * The 'ecanf' and 'ecanb' attributes, used to indicate the use of
of echo cancellation, and to parameterize the this function. of echo cancellation, and to parameterize the this function.
* The 'gcf' and 'gcb' attributes, used to indicate the use of * The 'gcf' and 'gcb' attributes, used to indicate the use of
Rajesh Kumar, Mohamed Mostafa. 19
of gain control, and to parameterize the this function. of gain control, and to parameterize the this function.
* The 'profileDesc' attribute which can be used to describe * The 'profileDesc' attribute which can be used to describe
AAL2 profiles. Although any AAL2 profile can be so described, AAL2 profiles. Although any AAL2 profile can be so described,
this attribute is useful for describing, at connection this attribute is useful for describing, at connection
establishment time, custom profiles that might not be known establishment time, custom profiles that might not be known
to the far end. This attribute applies in the AAL2 context to the far end. This attribute applies in the AAL2 context
only. only.
* The 'vsel' attribute which indicates a prioritized list of * The 'vsel' attribute which indicates a prioritized list of
3-tuples for voice service. Each 3-tuple indicates a codec, 3-tuples for voice service. Each 3-tuple indicates a codec,
an optional packet length and an optional packetization an optional packet length and an optional packetization
period. This complements the 'm' line information and should period. This complements the 'm' line information and should
be consistent with it. be consistent with it.
* The 'dsel' attribute which indicates a prioritized list of * The 'dsel' attribute which indicates a prioritized list of
3-tuples for voiceband data service. Each 3-tuple indicates a 3-tuples for voiceband data service. Each 3-tuple indicates a
codec, an optional packet length and an optional packetization codec, an optional packet length and an optional packetization
period. This complements the 'm' line information and should period. This complements the 'm' line information and should
Rajesh Kumar, Mohamed Mostafa. 24
be consistent with it. be consistent with it.
* The 'fsel' attribute which indicates a prioritized list of * The 'fsel' attribute which indicates a prioritized list of
3-tuples for facsimile service. Each 3-tuple indicates a 3-tuples for facsimile service. Each 3-tuple indicates a
codec, an optional packet length and an optional packetization codec, an optional packet length and an optional packetization
period. This complements the 'm' line information and should period. This complements the 'm' line information and should
be consistent with it. be consistent with it.
* The 'codecconfig' attribute which is used to represent the
contents of the single codec information element (IE) defined
in ITU Q.765.5 [57].
* The 'isup_usi' attribute which is used to represent
the 'User Information Layer 1 protocol' field within the
bearer capability information element defined in Section
4.5.5 of ITU Q.931 [59].
* The 'capability' attribute which indicates the ATM transfer * The 'capability' attribute which indicates the ATM transfer
capability (ITU nomenclature), synonymous with the ATM Service capability (ITU nomenclature), synonymous with the ATM Service
Category (ATMF nomenclature). Category (ATMF nomenclature).
* The 'qosClass' attribute which indicates the QoS class of the * The 'qosClass' attribute which indicates the QoS class of the
ATM bearer connection. ATM bearer connection.
* The 'bcob' attribute which indicates the broadband connection * The 'bcob' attribute which indicates the broadband connection
oriented bearer class. oriented bearer class.
* The 'stc' attribute which indicates susceptibility to * The 'stc' attribute which indicates susceptibility to
clipping. clipping.
* The 'upcc' attribute which indicates the user plane connection * The 'upcc' attribute which indicates the user plane connection
configuration. configuration.
* The 'atmQOSfparms' and 'atmQOSbparms' attributes are * The 'atmQOSfparms' and 'atmQOSbparms' attributes are
used to describe certain key ATM QoS parameters in the forward used to describe certain key ATM QoS parameters in the forward
and backward directions respectively. and backward directions respectively.
* The 'aal2QOSfparms' and 'aal2QOSbparms' attributes which
are placeholders for AAL2-level impairments, yet to be defined.
These attributes may be withdrawn if not needed.
* The 'atmFtrfcDesc' and 'atmBtrfcDesc' attributes which are * The 'atmFtrfcDesc' and 'atmBtrfcDesc' attributes which are
used to describe ATM traffic descriptor parameters in the used to describe ATM traffic descriptor parameters in the
forward and backward directions respectively. forward and backward directions respectively.
* The 'aal2FtrfcDesc' and 'aal2BtrfcDesc' attributes which
are placeholders for AAL2-level traffic descriptors,
yet to be defined. These attributes may be withdrawn if not
needed.
* The 'abrFparms' and 'abrBparms' attributes which are * The 'abrFparms' and 'abrBparms' attributes which are
used to describe ABR-specific parameters in the used to describe ABR-specific parameters in the
forward and backward directions respectively. These parameters forward and backward directions respectively. These parameters
are per the UNI 4.0 signaling specification [5]. are per the UNI 4.0 signaling specification [5].
* The 'clkrec' attribute which indicates the clock recovery * The 'clkrec' attribute which indicates the clock recovery
method for AAL1 unstructured data transfer (UDT). method for AAL1 unstructured data transfer (UDT).
* The 'fec' attribute which indicates the use of * The 'fec' attribute which indicates the use of
forward error correction. forward error correction.
* The 'prtfl' attribute which indicates indicate the fill * The 'prtfl' attribute which indicates indicate the fill
level of partially filled cells. level of partially filled cells.
* The 'bearerType' attribute is used to indicate * The 'bearerType' attribute is used to indicate
whether the underlying bearer is an ATM PVC/SPVC, an ATM SVC, whether the underlying bearer is an ATM PVC/SPVC, an ATM SVC,
or an AAL2 CID connection within an existing ATM SVC/PVC/SPVC. or an AAL2 CID connection within an existing ATM SVC/PVC/SPVC.
* When present, the 'structure' attribute is used to indicate * When present, the 'structure' attribute is used to indicate
the presence or absence of AAL1 structured data transfer (SDT), the presence or absence of AAL1 structured data transfer (SDT),
Rajesh Kumar, Mohamed Mostafa. 20
and the size of the SDT blocks. and the size of the SDT blocks.
* When present, the 'sbc' media attribute line denotes the * When present, the 'sbc' media attribute line denotes the
subchannel count in the case of n x 64 clear channel subchannel count in the case of n x 64 clear channel
communication. communication.
* When present, the 'fcpsSDUsize' and 'bcpsSDUsize' * When present, the 'fcpsSDUsize' and 'bcpsSDUsize'
attributes are used to indicate the maximum size of the attributes are used to indicate the maximum size of the
CPCS SDU payload in the forward and backward directions. CPCS SDU payload in the forward and backward directions.
Rajesh Kumar, Mohamed Mostafa. 25
* When present, the 'aal2CPS' attribute is used to * When present, the 'aal2CPS' attribute is used to
indicate that an AAL2 CPS sublayer as defined in indicate that an AAL2 CPS sublayer as defined in
ITU I.363.2 [13] is associated with the VCC referred to in the ITU I.363.2 [13] is associated with the VCC referred to in the
'm' line. Optionally, it can be used to indicate selected 'm' line. Optionally, it can be used to indicate selected
CPS options and parameter values for this VCC. CPS options and parameter values for this VCC.
* When present, the 'aal2sscs3661' attribute is used to * When present, the 'aal2sscs3661unassured' attribute is used
indicate the presence of an AAL2 SSCS sublayer as defined to indicate the presence of an AAL2 SSCS sublayer with
in ITU I.366.1 [12]. Optionally, it can be used to indicate unassured transmission as defined in ITU I.366.1 [12].
selected options and parameter values for this SSCS. Optionally, it can be used to indicate selected options and
parameter values for this SSCS.
* When present, the 'aal2sscs3661assured' attribute is used
to indicate the presence of an AAL2 SSCS sublayer with
assured transmission as defined in ITU I.366.1 [12].
Optionally, it can be used to indicate selected options and
parameter values for this SSCS.
* When present, the 'aal5sscop' attribute is used to
indicate the existence of an SSCOP protocol layer over
an AAL5 CPS layer, and the parameters which pertain to
this SSCOP layer.
* When present, the 'aal2sscs3662' attribute is used to * When present, the 'aal2sscs3662' attribute is used to
indicate the presence of an AAL2 SSCS sublayer as defined indicate the presence of an AAL2 SSCS sublayer as defined
in ITU I.366.2. Optionally, it can be used to indicate in ITU I.366.2. Optionally, it can be used to indicate
selected options and parameter values for this SSCS. selected options and parameter values for this SSCS.
* When present, the 'aalApp' attribute is used to point to the * When present, the 'aalApp' attribute is used to point to the
controlling standard for an application layer above the ATM controlling standard for an application layer above the ATM
adaptation layer. adaptation layer.
* When present, the 'lij' attribute is used to indicate the * When present, the 'lij' attribute is used to indicate the
presence of a connection that uses the Leaf-initiated-join presence of a connection that uses the Leaf-initiated-join
capability described in UNI 4.0 [5], and to optionally capability described in UNI 4.0 [5], and to optionally
describe parameters associated with this capability. describe parameters associated with this capability.
* When present, the 'anycast' attribute line is used to * When present, the 'anycast' attribute line is used to
indicate the applicability of the anycast function described indicate the applicability of the anycast function described
in UNI 4.0 [5], and to optionally qualify it with certain in UNI 4.0 [5], and to optionally qualify it with certain
parameters. parameters.
* When present, the 'cache' attribute line is used to enable
SVC caching and to specify an inactivity timer for SVC release.
* The 'fmtp' attribute line defined in the SDP standard can be * The 'fmtp' attribute line defined in the SDP standard can be
used to describe higher-layer parameters. These pertain used to describe higher-layer parameters. These pertain
to layers higher than the ATM adaptation layer that are to layers higher than the ATM adaptation layer that are
not closely coupled with the ATM or ATM adaptation layers. not closely coupled with the ATM or ATM adaptation layers.
Examples are the B-HLI and B-LLI IEs specified in ITU Q.2931 [15], Examples are the B-HLI and B-LLI IEs specified in ITU Q.2931 [15],
and the user-to-user information element described in and the user-to-user information element described in
ITU Q.2957 [48]. ITU Q.2957 [48].
* The 'chain' attribute line is used to chain consecutive SDP * The 'chain' attribute line is used to chain consecutive SDP
descriptions. descriptions.
The base specification for SDP, rfc2327 [1], allows the definition The base specification for SDP, rfc2327 [1], allows the definition
of new attributes. In keeping with this spirit, some of the attributes of new attributes. In keeping with this spirit, some of the attributes
listed above can also be used in SDP descriptions of IP listed above can also be used in SDP descriptions of IP
and other non-ATM sessions. For example, the 'vsel', 'dsel' and 'fsel' and other non-ATM sessions. For example, the 'vsel', 'dsel' and 'fsel'
attributes refer generically to codecs. These can be used for service- attributes refer generically to codecs. These can be used for service-
specific codec negotiation and assignment in non-ATM as well as specific codec negotiation and assignment in non-ATM as well as
Rajesh Kumar, Mohamed Mostafa. 26
ATM applications. ATM applications.
5.6.1 The 'atmmap' attribute 5.6.1 The 'atmmap' attribute
The 'atmmap' attribute is defined on the basis of the 'rtpmap' The 'atmmap' attribute is defined on the basis of the 'rtpmap'
attribute used in RFC2327. attribute used in RFC2327.
a=atmmap:<payloadType> <encodingName> a=atmmap:<payloadType> <encodingName>
The 'atmmap' attribute is used to dynamically map encoding names The 'atmmap' attribute is used to dynamically map encoding names
into payload types. This is necessary for those encoding names which into payload types. This is necessary for those encoding names which
have not been assigned a static payload type through IANA [31]. Payload have not been assigned a static payload type through IANA [31]. Payload
types and encoding techniques that have been registered with IANA types and encoding techniques that have been registered with IANA
for RTP are retained for AAL1 and AAL5. for RTP are retained for AAL1 and AAL5.
Rajesh Kumar, Mohamed Mostafa. 21
The range of statically defined payload types is in the range The range of statically defined payload types is in the range
0-95. All static assignments of payload types to codecs are 0-95. All static assignments of payload types to codecs are
listed in [31]. The range of payload types defined dynamically listed in [31]. The range of payload types defined dynamically
via the 'atmmap' attribute is 96-127. via the 'atmmap' attribute is 96-127.
Table 2 lists standard encoding names with their corresponding statically In addition to reiterating the payload types and encoding
mapped payload types [31]. It also suggests encoding names for names in [31], Table 2 defines non-standard encoding names
codecs not addressed in [31]. For these, payload types are mapped (with "X-" prefixes). Note that [31], rather than Table 2,
dynamically via the 'atmmap' attribute. Table 2 is not meant to be an is the authoritative list of standard codec names and payload
exhaustive list of codec names. types in the ATM context.
Rajesh Kumar, Mohamed Mostafa. 22 Rajesh Kumar, Mohamed Mostafa. 27
Table 2: Encoding Names and Payload Types Table 2: Encoding Names and Payload Types
|---------------------|--------------|---------------------------| |---------------------|--------------|---------------------------|
| Encoding Technique | Encoding Name| Payload type | | Encoding Technique | Encoding Name| Payload type |
|---------------------|--------------|---------------------------| |---------------------|--------------|---------------------------|
| PCM - Mu law | "PCMU" | 0 (Statically Mapped) | | PCM - Mu law | "PCMU" | 0 (Statically Mapped) |
|---------------------|--------------|---------------------------| |---------------------|--------------|---------------------------|
| 32 kbps ADPCM | "G726-32" | 2 (Statically Mapped) | | 32 kbps ADPCM | "G726-32" | 2 (Statically Mapped) |
|---------------------|--------------|---------------------------| |---------------------|--------------|---------------------------|
|Dual rate 5.3/6.3kbps| "G723" | 4 (Statically Mapped) | |Dual rate 5.3/6.3kbps| "G723" | 4 (Statically Mapped) |
|---------------------|--------------|---------------------------| |---------------------|--------------|---------------------------|
skipping to change at line 1371 skipping to change at line 1455
| kbps - high rate | | | | kbps - high rate | | |
|---------------------|--------------|---------------------------| |---------------------|--------------|---------------------------|
| Dual rate 5.3/6.3 |"X-G7231-L" | None, map dynamically | | Dual rate 5.3/6.3 |"X-G7231-L" | None, map dynamically |
| kbps - low rate | | | | kbps - low rate | | |
|---------------------|--------------|---------------------------| |---------------------|--------------|---------------------------|
| Dual rate 5.3/6.3 |"X-G7231a-H" | None, map dynamically | | Dual rate 5.3/6.3 |"X-G7231a-H" | None, map dynamically |
| kbps - high rate w/ | | | | kbps - high rate w/ | | |
| ITU-defined silence | | | | ITU-defined silence | | |
| suppression | | | | suppression | | |
|----------------------------------------------------------------| |----------------------------------------------------------------|
Rajesh Kumar, Mohamed Mostafa. 28
+---------------------+--------------+---------------------------+
| Dual rate 5.3/6.3 |"X-G7231a-L" | None, map dynamically | | Dual rate 5.3/6.3 |"X-G7231a-L" | None, map dynamically |
| kbps - high rate w/ | | | | kbps - high rate w/ | | |
| ITU-defined silence | | | | ITU-defined silence | | |
| suppression | | | | suppression | | |
|---------------------|--------------|---------------------------| |---------------------|--------------|---------------------------|
| 16 kbps EADPCM | "X-G727-16" | None, map dynamically | | 16 kbps EADPCM | "X-G727-16" | None, map dynamically |
|---------------------|--------------|---------------------------| |---------------------|--------------|---------------------------|
Rajesh Kumar, Mohamed Mostafa. 23
+---------------------+--------------+---------------------------+
| 24 kbps EADPCM | "X-G727-24" | None, map dynamically | | 24 kbps EADPCM | "X-G727-24" | None, map dynamically |
|---------------------|--------------|---------------------------| |---------------------|--------------|---------------------------|
| 32 kbps EADPCM | "X-G727-32" | None, map dynamically | | 32 kbps EADPCM | "X-G727-32" | None, map dynamically |
|---------------------|--------------|---------------------------| |---------------------|--------------|---------------------------|
|n x 64 kbps Clear | "X-CCD" | None, map dynamically | |n x 64 kbps Clear | "X-CCD" | None, map dynamically |
|Channel without CAS | | | |Channel without CAS | | |
|per af-vtoa-78 [7] | | | |per af-vtoa-78 [7] | | |
|---------------------|--------------|---------------------------| |---------------------|--------------|---------------------------|
|n x 64 kbps Clear | "X-CCD-CAS" | None, map dynamically | |n x 64 kbps Clear | "X-CCD-CAS" | None, map dynamically |
|Channel with CAS | | | |Channel with CAS | | |
|per af-vtoa-78 [7] | | | |per af-vtoa-78 [7] | | |
|---------------------|--------------|---------------------------| |---------------------|--------------|---------------------------|
|GSM Full Rate | "GSM" | 3 (Statically Mapped) | |GSM Full Rate | "GSM" | 3 (Statically Mapped) |
|---------------------|--------------|---------------------------| |---------------------|--------------|---------------------------|
|GSM Half Rate | "X-GSM-HR" | None, map dynamically | |GSM Half Rate | "GSM-HR" | None, map dynamically |
|---------------------|--------------|---------------------------|
|GSM-Enhanced Full Rate "X-GSM-EFR" | None, map dynamically |
|---------------------|--------------|---------------------------| |---------------------|--------------|---------------------------|
|GSM-Enhanced Half Rate "X-GSM-EHR" | None, map dynamically | |GSM-Enhanced Full Rate "GSM-EFR" | None, map dynamically |
|---------------------|--------------|---------------------------| |---------------------|--------------|---------------------------|
|Group 3 fax demod. "X-FXDMOD-3" | None, map dynamically | |GSM-Enhanced Half Rate "GSM-EHR" | None, map dynamically |
|---------------------|--------------|---------------------------| |---------------------|--------------|---------------------------|
|Group 3 fax demod. "X-FXDMOD-3" | None, map dynamically | |Group 3 fax demod. "X-FXDMOD-3" | None, map dynamically |
|---------------------|--------------|---------------------------| |---------------------|--------------|---------------------------|
| Federal Standard | "1016" | 1 (Statically Mapped) | | Federal Standard | "1016" | 1 (Statically Mapped) |
| FED-STD 1016 CELP | | | | FED-STD 1016 CELP | | |
|---------------------|--------------|---------------------------| |---------------------|--------------|---------------------------|
| DVI4, 8 KHz [3] | "DVI4" | 5 (Statically Mapped) | | DVI4, 8 KHz [3] | "DVI4" | 5 (Statically Mapped) |
|---------------------|--------------|---------------------------| |---------------------|--------------|---------------------------|
| DVI4, 16 KHz [3] | "DVI4" | 6 (Statically Mapped) | | DVI4, 16 KHz [3] | "DVI4" | 6 (Statically Mapped) |
|---------------------|--------------|---------------------------| |---------------------|--------------|---------------------------|
skipping to change at line 1427 skipping to change at line 1509
| Double channel | | | | Double channel | | |
|---------------------|--------------|---------------------------| |---------------------|--------------|---------------------------|
| L16 [3], Sixteen | "L16" | 11 (Statically Mapped) | | L16 [3], Sixteen | "L16" | 11 (Statically Mapped) |
| Bit Linear PCM, | | | | Bit Linear PCM, | | |
| Single channel | | | | Single channel | | |
|---------------------|--------------|---------------------------| |---------------------|--------------|---------------------------|
| QCELP [3] | "QCELP" | 12 (Statically Mapped) | | QCELP [3] | "QCELP" | 12 (Statically Mapped) |
|---------------------|--------------|---------------------------| |---------------------|--------------|---------------------------|
| MPEG1/MPEG2 audio | "MPA" | 14 (Statically Mapped) | | MPEG1/MPEG2 audio | "MPA" | 14 (Statically Mapped) |
|---------------------|--------------|---------------------------| |---------------------|--------------|---------------------------|
Rajesh Kumar, Mohamed Mostafa. 29
+---------------------+--------------+---------------------------+
| DVI4, 11.025 KHz[3] | "DVI4" | 16 (Statically Mapped) | | DVI4, 11.025 KHz[3] | "DVI4" | 16 (Statically Mapped) |
|---------------------|--------------|---------------------------| |---------------------|--------------|---------------------------|
| DVI4, 22.05 KHz [3] | "DVI4" | 17 (Statically Mapped) | | DVI4, 22.05 KHz [3] | "DVI4" | 17 (Statically Mapped) |
|---------------------|--------------|---------------------------| |---------------------|--------------|---------------------------|
| MPEG1/MPEG2 video | "MPV" | 32 (Statically Mapped) | | MPEG1/MPEG2 video | "MPV" | 32 (Statically Mapped) |
|---------------------|--------------|---------------------------| |---------------------|--------------|---------------------------|
| MPEG 2 audio/video | "MP2T" | 33 (Statically Mapped) | | MPEG 2 audio/video | "MP2T" | 33 (Statically Mapped) |
| transport stream | | | | transport stream | | |
|---------------------|--------------|---------------------------| |---------------------|--------------|---------------------------|
Rajesh Kumar, Mohamed Mostafa. 24
|---------------------|--------------|---------------------------|
| ITU H.261 video | "H261" | 31 (Statically Mapped) | | ITU H.261 video | "H261" | 31 (Statically Mapped) |
|---------------------|--------------|---------------------------| |---------------------|--------------|---------------------------|
| ITU H.263 video | "H263" | 33 (Statically Mapped) | | ITU H.263 video | "H263" | 33 (Statically Mapped) |
|---------------------|--------------|---------------------------| |---------------------|--------------|---------------------------|
| ITU H.263 video |"H263-1998" | None, map dynamically | | ITU H.263 video |"H263-1998" | None, map dynamically |
| 1998 version | | | | 1998 version | | |
|---------------------|--------------|---------------------------| |---------------------|--------------|---------------------------|
| MPEG 1 system stream| "MP1S" | None, map dynamically | | MPEG 1 system stream| "MP1S" | None, map dynamically |
|---------------------|--------------|---------------------------| |---------------------|--------------|---------------------------|
|MPEG 2 program stream| "MP2P" | None, map dynamically | |MPEG 2 program stream| "MP2P" | None, map dynamically |
|---------------------|--------------|---------------------------| |---------------------|--------------|---------------------------|
|Redundancy | "RED" | None, map dynamically |
|---------------------|--------------|---------------------------|
|Variable rate DVI4 | "VDVI" | None, map dynamically |
|---------------------|--------------|---------------------------|
|Cell-B | "CelB" | 25 |
|---------------------|--------------|---------------------------|
|JPEG | "JPEG" | 26 |
|---------------------|--------------|---------------------------|
|nv | "nv" | 28 |
|---------------------|--------------|---------------------------|
|L8, Eight Bit Linear | "L8" | None, map dynamically |
|PCM | | |
|---------------------|--------------|---------------------------|
| ITU-R Recommendation| "BT656" | None, map dynamically |
| BT.656-3 for | | |
| digital video | | |
|---------------------|--------------|---------------------------|
| Adaptive Multirate | "FR-AMR" | None, map dynamically |
|-Full Rate (3GPP)[58]| | |
|---------------------|--------------|---------------------------|
| Adaptive Multirate | "HR-AMR" | None, map dynamically |
|-Half Rate (3GPP)[58]| | |
|---------------------|--------------|---------------------------|
| Adaptive Multirate | "HR-UMTS" | None, map dynamically |
|- UMTS(3GPP) [58] | | |
|---------------------|--------------|---------------------------|
5.6.2 The 'eecid' attribute 5.6.2 The 'eecid' attribute
The 'eecid' attribute is synonymous with the 4-byte'bnc-id' The 'eecid' attribute is synonymous with the 4-byte'bnc-id'
Rajesh Kumar, Mohamed Mostafa. 30
parameter used by T1SI, the ATM forum and the ITU (Q.1901) parameter used by T1SI, the ATM forum and the ITU (Q.1901)
standardization effort. The term 'eecid' stands for 'end-to-end standardization effort. The term 'eecid' stands for 'end-to-end
connection identifier', while 'bnc-id' stands for 'backbone network connection identifier', while 'bnc-id' stands for 'backbone network
connection identifier'. The name "backbone" is slightly misleading connection identifier'. The name "backbone" is slightly misleading
since it refers to the entire ATM network including the ATM edge and since it refers to the entire ATM network including the ATM edge and
ATM core networks. In Q.1901 terminology, an ATM "backbone" ATM core networks. In Q.1901 terminology, an ATM "backbone"
connects TDM or analog edges. connects TDM or analog edges.
While the term 'bnc-id' might be used in the bearer signaling plane While the term 'bnc-id' might be used in the bearer signaling plane
and in an ISUP (Q.1901) call control plane, SDP session descriptors and in an ISUP (Q.1901) call control plane, SDP session descriptors
use the neutral term 'eecid'. This provides a common SDP baseline use the neutral term 'eecid'. This provides a common SDP baseline
for applications that use ISUP (Q.1901) and applications that use for applications that use ISUP (Q.1901) and applications that use
SIP/SIP+. SIP/SIP+.
Section 5.6.38 depicts the use of the eecid in call establishment Section 5.6.40 depicts the use of the eecid in call establishment
procedures. In these procedures, the eecid is used to correlate procedures. In these procedures, the eecid is used to correlate
service-level calls with SVC set-up requests. service-level calls with SVC set-up requests.
In the forward SVC establishment model, the call-terminating gateway In the forward SVC establishment model, the call-terminating gateway
selects an eecid and transmits it via SDP to the call-originating selects an eecid and transmits it via SDP to the call-originating
gateway. The call originating gateway transmits this eecid to the gateway. The call originating gateway transmits this eecid to the
call terminating gateway via the bearer set-up message (SVC set-up call terminating gateway via the bearer set-up message (SVC set-up
or Q.2630.1 establish request). or Q.2630.1 establish request).
In the backward SVC establishment model, the call-originating gateway In the backward SVC establishment model, the call-originating gateway
skipping to change at line 1498 skipping to change at line 1608
attribute is used to correlate, one-to-one, received bearer set-up attribute is used to correlate, one-to-one, received bearer set-up
requests with service-level call control signaling. requests with service-level call control signaling.
Within an SDP session description, the eecid attribute is used as Within an SDP session description, the eecid attribute is used as
follows: follows:
a=eecid:<eecid> a=eecid:<eecid>
where <eecid> consists of up to 8 hex digits (equivalent to 4 where <eecid> consists of up to 8 hex digits (equivalent to 4
octets). Since this is always represented in hex, the "0x" octets). Since this is always represented in hex, the "0x"
Rajesh Kumar, Mohamed Mostafa. 25
prefix shall not be used. prefix shall not be used.
Within the text representation of the <eecid> parameter, hex digits
to the left are more significant than hex digits to the right
(Section 2.2).
This SDP document does not specify how the eecid (synonymous This SDP document does not specify how the eecid (synonymous
Rajesh Kumar, Mohamed Mostafa. 31
with bnc-id) is to be communicated through bearer signaling with bnc-id) is to be communicated through bearer signaling
(Q.931, UNI, PNNI, AINI, IISP, proprietary signaling equivalent, (Q.931, UNI, PNNI, AINI, IISP, proprietary signaling equivalent,
Q.2630.1). This is a task of these bearer signaling protocols. Q.2630.1). This is a task of these bearer signaling protocols.
However, the following informative statements are made to However, the following informative statements are made to
convey a sense of the interoperability that is a goal of convey a sense of the interoperability that is a goal of
current standardization efforts: current standardization efforts:
- ITU Q.2941.3 and the ATMF each recommend the use of the - ITU Q.2941.3 and the ATMF each recommend the use of the
GIT IE for carrying the eecid (synonymous with bnc-id) GIT IE for carrying the eecid (synonymous with bnc-id)
in the set-up message of ATM signaling protocols (Q.2931, in the set-up message of ATM signaling protocols (Q.2931,
skipping to change at line 1553 skipping to change at line 1667
Here, <aalType> can take on the following string values: Here, <aalType> can take on the following string values:
"AAL1", "AAL1_SDT", "AAL1_UDT", "AAL2", "AAL3/4", "AAL5" "AAL1", "AAL1_SDT", "AAL1_UDT", "AAL2", "AAL3/4", "AAL5"
and "USER_DEFINED_AAL". Note that "AAL3/4" and "USER DEFINED AAL" and "USER_DEFINED_AAL". Note that "AAL3/4" and "USER DEFINED AAL"
are not addressed in this document. are not addressed in this document.
5.6.4 The 'silenceSupp' attribute 5.6.4 The 'silenceSupp' attribute
When present, the 'silenceSupp' attribute is used to indicate When present, the 'silenceSupp' attribute is used to indicate
the use or non-use of silence suppression. the use or non-use of silence suppression.
Rajesh Kumar, Mohamed Mostafa. 32
The format of the 'silenceSupp' media attribute line is The format of the 'silenceSupp' media attribute line is
as follows: as follows:
a=silenceSupp: <silenceSuppEnable> <silenceTimer> <suppPref> <sidUse> a=silenceSupp: <silenceSuppEnable> <silenceTimer> <suppPref> <sidUse>
<fxnslevel> <fxnslevel>
Rajesh Kumar, Mohamed Mostafa. 26
If any of the parameters in the silenceSupp media attribute line If any of the parameters in the silenceSupp media attribute line
is not specified, is inapplicable or is implied, then it is set to is not specified, is inapplicable or is implied, then it is set to
"-". "-".
The <silenceSuppEnable> can take on values of "on" or "off". If it The <silenceSuppEnable> can take on values of "on" or "off". If it
is "on", then silence suppression is enabled. is "on", then silence suppression is enabled.
The <silenceTimer> is a 16-bit field which can be represented in The <silenceTimer> is a 16-bit field which can be represented in
decimal or hex. Each increment (tick) of this timer represents decimal or hex. Each increment (tick) of this timer represents
a millisecond. The maximum value of this timer is between 1 and 3 a millisecond. The maximum value of this timer is between 1 and 3
skipping to change at line 1598 skipping to change at line 1713
The <sidUse> indicates whether SIDs (Silence Insertion The <sidUse> indicates whether SIDs (Silence Insertion
Descriptors) are to be used, and whether they use fixed comfort Descriptors) are to be used, and whether they use fixed comfort
noise or sampled background noise. It can take on the noise or sampled background noise. It can take on the
string values of "No SID", "Fixed Noise", "Sampled Noise". string values of "No SID", "Fixed Noise", "Sampled Noise".
If the value of <sidUse> is "Fixed Noise", then <fxnslevel> If the value of <sidUse> is "Fixed Noise", then <fxnslevel>
provides its level. It can take on integer values in the range provides its level. It can take on integer values in the range
0-127, as follows: 0-127, as follows:
Rajesh Kumar, Mohamed Mostafa. 33
+-----------------------+---------------------+ +-----------------------+---------------------+
| <fxnslevel> value | Meaning | | <fxnslevel> value | Meaning |
+-----------------------+---------------------+ +-----------------------+---------------------+
| 0-29 | Reserved | | 0-29 | Reserved |
| 30 | -30 dBm0 | | 30 | -30 dBm0 |
| 31 | -31 dBm0 | | 31 | -31 dBm0 |
| . . . | . . . | | . . . | . . . |
| 77 | -77 dBm0 | | 77 | -77 dBm0 |
| 78 | -78 dBm0 | | 78 | -78 dBm0 |
| 79-126 | reserved | | 79-126 | reserved |
skipping to change at line 1619 skipping to change at line 1735
+-----------------------+---------------------+ +-----------------------+---------------------+
In addition to the decimal representation of <fxnslevel>, a In addition to the decimal representation of <fxnslevel>, a
hex representation, preceded by a "0x" prefix, is also allowed. hex representation, preceded by a "0x" prefix, is also allowed.
5.6.5 The 'ecanf' and 'ecanb' attributes 5.6.5 The 'ecanf' and 'ecanb' attributes
When present, the 'ecanf' and 'ecanb' attributes are used to indicate When present, the 'ecanf' and 'ecanb' attributes are used to indicate
the use or non-use of echo cancellation in the forward the use or non-use of echo cancellation in the forward
and backward directions respectively. See Section and backward directions respectively. See Section
Rajesh Kumar, Mohamed Mostafa. 27
2.3 for a definition of the terms 'forward' and 'backward'. 2.3 for a definition of the terms 'forward' and 'backward'.
The format of the 'ecanf' and 'ecanb' media attribute lines is The format of the 'ecanf' and 'ecanb' media attribute lines is
as follows: as follows:
a=ecanf: <ecanEnable> <ecanType> a=ecanf: <ecanEnable> <ecanType>
a=ecanb: <ecanEnable> <ecanType> a=ecanb: <ecanEnable> <ecanType>
If any of the parameters in the ecanf and ecanb media attribute lines If any of the parameters in the ecanf and ecanb media attribute lines
is not specified, is inapplicable or is implied, then it is set to is not specified, is inapplicable or is implied, then it is set to
skipping to change at line 1651 skipping to change at line 1765
then echo cancellation is disabled. then echo cancellation is disabled.
The <ecanType> parameter can take on the string values "G165" and "G168" The <ecanType> parameter can take on the string values "G165" and "G168"
respectively. respectively.
When SDP is used with some media gateway control protocols such as MGCP When SDP is used with some media gateway control protocols such as MGCP
and Megaco [26], there exist means outside SDP descriptions to specify and Megaco [26], there exist means outside SDP descriptions to specify
the echo cancellation properties of a connection. Nevertheless, this the echo cancellation properties of a connection. Nevertheless, this
media attribute line is included for completeness. As a result, the media attribute line is included for completeness. As a result, the
SDP can be used for describing echo cancellation in applications SDP can be used for describing echo cancellation in applications
Rajesh Kumar, Mohamed Mostafa. 34
where alternate means for this are unavailable. where alternate means for this are unavailable.
5.6.6 The 'gcf' and 'gcb' attributes 5.6.6 The 'gcf' and 'gcb' attributes
When present, the 'gcf' and 'gcb' attributes are used to indicate When present, the 'gcf' and 'gcb' attributes are used to indicate
the use or non-use of gain control in the forward and backward the use or non-use of gain control in the forward and backward
directions respectively. See Section 2.3 for a definition of the directions respectively. See Section 2.3 for a definition of the
terms 'forward' and 'backward'. terms 'forward' and 'backward'.
The format of the 'gcf' and 'gcb' media attribute lines is as The format of the 'gcf' and 'gcb' media attribute lines is as
skipping to change at line 1682 skipping to change at line 1798
etc. etc.
The <gcEnable> parameter can take on values of "on" or "off". If it The <gcEnable> parameter can take on values of "on" or "off". If it
is "on", then gain control is enabled. If it is "off", then is "on", then gain control is enabled. If it is "off", then
gain control is disabled. gain control is disabled.
The <gcLvl> parameter is represented as the decimal or hex The <gcLvl> parameter is represented as the decimal or hex
equivalent of a 16-bit binary field. A value of 0xFFFF implies equivalent of a 16-bit binary field. A value of 0xFFFF implies
automatic gain control. Otherwise, this number indicates the automatic gain control. Otherwise, this number indicates the
number of decibels of inserted loss. The upper bound, 65,535 dB number of decibels of inserted loss. The upper bound, 65,535 dB
Rajesh Kumar, Mohamed Mostafa. 28
(0xFFFE) of inserted loss, is an absurdly large number and is a (0xFFFE) of inserted loss, is an absurdly large number and is a
carryover from Megaco [26]. In practical applications, the inserted loss carryover from Megaco [26]. In practical applications, the inserted loss
is much lower. is much lower.
When SDP is used with some media gateway control protocols such as MGCP When SDP is used with some media gateway control protocols such as MGCP
and Megaco [26], there exist means outside SDP descriptions to specify and Megaco [26], there exist means outside SDP descriptions to specify
the gain control properties of a connection. Nevertheless, this the gain control properties of a connection. Nevertheless, this
media attribute line is included for completeness. As a result, the media attribute line is included for completeness. As a result, the
SDP can be used for describing gain control in applications SDP can be used for describing gain control in applications
where alternate means for this are unavailable. where alternate means for this are unavailable.
skipping to change at line 1705 skipping to change at line 1819
5.6.7 The 'profileDesc' attribute 5.6.7 The 'profileDesc' attribute
There is one 'profileDesc' media attribute line for each AAL2 There is one 'profileDesc' media attribute line for each AAL2
profile that is intended to be described. The 'profileDesc' media profile that is intended to be described. The 'profileDesc' media
attribute line is structured as follows: attribute line is structured as follows:
a=profileDesc: <aal2transport> <profile> <uuiCodeRange#1> a=profileDesc: <aal2transport> <profile> <uuiCodeRange#1>
<encodingName#1> <packetLength#1> <packetTime#1> <encodingName#1> <packetLength#1> <packetTime#1>
<uuiCodeRange#2> <encodingName#2> <packetLength#2> <uuiCodeRange#2> <encodingName#2> <packetLength#2>
<packetTime#2>... <uuiCodeRange#N> <encodingName#N> <packetTime#2>... <uuiCodeRange#N> <encodingName#N>
Rajesh Kumar, Mohamed Mostafa. 35
<packetLength#N> <packetTime#N> <packetLength#N> <packetTime#N>
Here, <aal2transport> can have those values of <transport> (Table 1) that Here, <aal2transport> can have those values of <transport> (Table 1) that
pertain to AAL2. These are: pertain to AAL2. These are:
AAL2/ATMF AAL2/ATMF
AAL2/ITU AAL2/ITU
AAL2/custom AAL2/custom
AAL2/<corporateName> AAL2/<corporateName>
AAL2/IEEE:<oui> AAL2/IEEE:<oui>
skipping to change at line 1737 skipping to change at line 1853
The <encodingName> parameter can take one of the values in column 2 The <encodingName> parameter can take one of the values in column 2
of Table 2. Additionally, it can take on the following descriptor of Table 2. Additionally, it can take on the following descriptor
strings: "PCMG", "SIDG" and "SID729". These stand for generic PCM, strings: "PCMG", "SIDG" and "SID729". These stand for generic PCM,
generic SID and G.729 SID respectively. generic SID and G.729 SID respectively.
The <packetLength> is a decimal integer representation of the AAL2 The <packetLength> is a decimal integer representation of the AAL2
packet length in octets. packet length in octets.
The <packetTime> is a decimal integer representation of the AAL2 The <packetTime> is a decimal integer representation of the AAL2
packetization interval in ms. packetization interval in microseconds.
For instance, the 'profileDesc' media attribute line below defines For instance, the 'profileDesc' media attribute line below defines
the AAL2/custom 100 profile. This profile is reproduced in the Table 3 the AAL2/custom 100 profile. This profile is reproduced in the Table 3
below. For a description of the parameters in this profile such as below. For a description of the parameters in this profile such as
M and the sequence number interval, see ITU I.366.2 [13]. M and the sequence number interval, see ITU I.366.2 [13].
Rajesh Kumar, Mohamed Mostafa. 29 a=profileDesc:AAL2/custom 100 0-7 PCMG 40 5000 0-7 SIDG 1 5000 8-15
a=profileDesc:AAL2/custom 100 0-7 PCMG 40 5 0-7 SIDG 1 5 8-15 G726-32 40 10000 8-15 SIDG 1 5000
G726-32 40 10 8-15 SIDG 1 5
If the <packetTime> parameter is to be omitted or implied, then the If the <packetTime> parameter is to be omitted or implied, then the
same profile can be represented as follows: same profile can be represented as follows:
a=profileDesc:AAL2/custom 100 0-7 PCMG 40 - 0-7 SIDG 1 - 8-15 a=profileDesc:AAL2/custom 100 0-7 PCMG 40 - 0-7 SIDG 1 - 8-15
G726-32 40 - 8-15 SIDG 1 - G726-32 40 - 8-15 SIDG 1 -
If a gateway has a provisioned or hard coded definition of a If a gateway has a provisioned or hard coded definition of a
profile, then any definition provided via the 'profileDesc' line profile, then any definition provided via the 'profileDesc' line
overrides it. The exception to this rule is with regard to standard overrides it. The exception to this rule is with regard to standard
Rajesh Kumar, Mohamed Mostafa. 36
profiles such as ITU-defined profiles and ATMF-defined profiles. In profiles such as ITU-defined profiles and ATMF-defined profiles. In
general, these should not be defined via a 'profileDesc' media general, these should not be defined via a 'profileDesc' media
attribute line. If they are, then the definition needs to be attribute line. If they are, then the definition needs to be
consistent with the standard definition else the SDP session consistent with the standard definition else the SDP session
descriptor should be rejected with an appropriate error code. descriptor should be rejected with an appropriate error code.
Table 3: Example of a custom AAL2 profile Table 3: Example of a custom AAL2 profile
|---------------------------------------------------------------| |---------------------------------------------------------------|
| UUI | Packet |Encoding | | |Packet|Seq.No. | | UUI | Packet |Encoding | | |Packet|Seq.No. |
| Code | Length |per ITU |Description of | M |Time |Interval| | Code | Length |per ITU |Description of | M |Time |Interval|
skipping to change at line 1801 skipping to change at line 1918
The 'vsel' line is structured as follows: The 'vsel' line is structured as follows:
a=vsel:<encodingName #1> <packetLength #1><packetTime #1> a=vsel:<encodingName #1> <packetLength #1><packetTime #1>
<encodingName #2> <packetLength #2><packetTime #2> <encodingName #2> <packetLength #2><packetTime #2>
... ...
<encodingName #N> <packetLength #N><packetTime #N> <encodingName #N> <packetLength #N><packetTime #N>
where the <encodingName> parameter can take one of the values in column 2 of where the <encodingName> parameter can take one of the values in column 2 of
Table 2. The <packetLength> is a decimal integer representation of the Table 2. The <packetLength> is a decimal integer representation of the
packet length in octets. The <packetTime> is a decimal integer packet length in octets. The <packetTime> is a decimal integer
representation of the packetization interval in ms. The parameters representation of the packetization interval in microseconds. The parameters
<packetLength>and <packetTime> can be set to "-" when not needed. Also, the <packetLength>and <packetTime> can be set to "-" when not needed. Also, the
entire 'vsel' media attribute line can be omitted when not needed. entire 'vsel' media attribute line can be omitted when not needed.
For example, For example,
Rajesh Kumar, Mohamed Mostafa. 30 a=vsel:G729 10 10000 G726-32 40 10000
a=vsel:G729 10 10 G726-32 40 10
Rajesh Kumar, Mohamed Mostafa. 37
indicates first preference of G.729 or G.729a (both are interoperable) as indicates first preference of G.729 or G.729a (both are interoperable) as
the voice encoding scheme. A packet length of 10 octets and a packetization the voice encoding scheme. A packet length of 10 octets and a packetization
interval of 10 ms are associated with this codec. G726-32 is the second interval of 10 ms are associated with this codec. G726-32 is the second
preference stated in this line, with an associated packet length of 40 preference stated in this line, with an associated packet length of 40
octets and a packetization interval of 10 ms. If the packet length and octets and a packetization interval of 10 ms. If the packet length and
packetization interval are intended to be omitted, then this media attribute packetization interval are intended to be omitted, then this media attribute
line becomes line becomes
a=vsel:G729 - - G726-32 - - a=vsel:G729 - - G726-32 - -
The media attribute line The media attribute line
a=vsel:G726-32 40 10 a=vsel:G726-32 40 10000
indicates preference for or selection of 32 kbps ADPCM with a packet indicates preference for or selection of 32 kbps ADPCM with a packet
length of 40 octets and a packetization interval of 10 ms. length of 40 octets and a packetization interval of 10 ms.
This media attribute line can be used in ATM as well as non-ATM contexts. This media attribute line can be used in ATM as well as non-ATM contexts.
Within the ATM context, it can be applied to the AAL1, AAL2 and AAL5 Within the ATM context, it can be applied to the AAL1, AAL2 and AAL5
adaptations. The <packetLength> and <packetTime> are not meaningful adaptations. The <packetLength> and <packetTime> are not meaningful
in the AAL1 case and should be set to "-". In the AAL2 case, in the AAL1 case and should be set to "-". In the AAL2 case,
this line determines the use of some or all of the rows in this line determines the use of some or all of the rows in
a given profile table. If multiple 3-tuples are present, they a given profile table. If multiple 3-tuples are present, they
can indicate a hierarchical assignment of some rows in that can indicate a hierarchical assignment of some rows in that
profile to voice service e.g. row A preferred to row B etc. profile to voice service e.g. row A preferred to row B etc.
If multiple profiles are present on the 'm' line, the profile If multiple profiles are present on the 'm' line, the profile
qualified by this attribute is the first qualified by this attribute is the first
profile. If a single profile that has been selected for a connection profile. If a single profile that has been selected for a connection
is indicated in the 'm' line, the 'vsel' attribute qualifies the is indicated in the 'm' line, the 'vsel' attribute qualifies the
use, for voice service, of codecs within that profile. use, for voice service, of codecs within that profile.
With most of the encoding names in Figure 2, the packet length
and packetization period can be derived from each other. One of them
can be set to "-" without a loss of information. There are some
exceptions such as the IANA-registered encoding names G723, DVI4 and
L16 for which this is not true. Therefore, there is a need to
retain both the packet length and packetization period in the
definition of the 'vsel' line.
5.6.9 The 'dsel' attribute 5.6.9 The 'dsel' attribute
The 'dsel' attribute indicates a prioritized list of The 'dsel' attribute indicates a prioritized list of
one or more 3-tuples for voiceband data service. The <fxIncl> one or more 3-tuples for voiceband data service. The <fxIncl>
flag indicates whether this definition of voiceband data flag indicates whether this definition of voiceband data
includes fax ("on" value) or not ("off" value). If <fxIncl> is includes fax ("on" value) or not ("off" value). If <fxIncl> is
"on", then the 'dsel' line must be consistent with any 'fsel' line "on", then the 'dsel' line must be consistent with any 'fsel' line
in the session description. In this case, an error event is generated in the session description. In this case, an error event is generated
in the case of inconsistency. Each 3-tuple indicates a codec, in the case of inconsistency. Each 3-tuple indicates a codec,
an optional packet length and an optional packetization an optional packet length and an optional packetization
period. This complements the 'm' line information and should period. This complements the 'm' line information and should
be consistent with it. be consistent with it.
Rajesh Kumar, Mohamed Mostafa. 38
The 'dsel' line is structured as follows: The 'dsel' line is structured as follows:
a=dsel:<fxIncl> <encodingName #1> <packetLength #1><packetTime #1> a=dsel:<fxIncl> <encodingName #1> <packetLength #1><packetTime #1>
<encodingName #2> <packetLength #2><packetTime #2> <encodingName #2> <packetLength #2><packetTime #2>
... ...
<encodingName #N> <packetLength #N><packetTime #N> <encodingName #N> <packetLength #N><packetTime #N>
where the <encodingName> parameter can take one of the values in where the <encodingName> parameter can take one of the values in
column 2 of Table 2. The <packetLength> and <packetTime> column 2 of Table 2. The <packetLength> and <packetTime>
parameters are per their definition, above, for the 'vsel' parameters are per their definition, above, for the 'vsel'
media attribute line. The parameters <packetLength>and <packetTime>) media attribute line. The parameters <packetLength>and <packetTime>)
can be set to "-" when not needed. The <fxIncl> flag is presumed to be can be set to "-" when not needed. The <fxIncl> flag is presumed to be
"off" if it is set to "-". Also, the entire 'dsel' media attribute line "off" if it is set to "-". Also, the entire 'dsel' media attribute line
can be omitted when not needed. can be omitted when not needed.
Rajesh Kumar, Mohamed Mostafa. 31
For example, For example,
a=dsel:- G726-32 20 5 PCMU 40 5 a=dsel:- G726-32 20 5000 PCMU 40 5000
indicates that this line does not address facsimile, and that the indicates that this line does not address facsimile, and that the
first preference for the voiceband data codes is 32 kbps ADPCM, first preference for the voiceband data codes is 32 kbps ADPCM,
while the second preference is PCMU. The packet length while the second preference is PCMU. The packet length
and the packetization interval associated with G726-32 are 20 octets and and the packetization interval associated with G726-32 are 20 octets and
5 ms respectively. For PCMU, they are 40 octets and 5 ms respectively. 5 ms respectively. For PCMU, they are 40 octets and 5 ms respectively.
This media attribute line can be used in ATM as well as non-ATM contexts. This media attribute line can be used in ATM as well as non-ATM contexts.
Within the ATM context, it can be applied to the AAL1, AAL2 and AAL5 Within the ATM context, it can be applied to the AAL1, AAL2 and AAL5
adaptations. The <packetLength> and <packetTime> are not meaningful adaptations. The <packetLength> and <packetTime> are not meaningful
skipping to change at line 1894 skipping to change at line 2019
this line determines the use of some or all of the rows in this line determines the use of some or all of the rows in
a given profile table. If multiple 3-tuples are present, they a given profile table. If multiple 3-tuples are present, they
can indicate a hierarchical assignment of some rows in that can indicate a hierarchical assignment of some rows in that
profile to voiceband data service e.g. row A preferred to row B etc. profile to voiceband data service e.g. row A preferred to row B etc.
If multiple profiles are present on the 'm' line, the profile If multiple profiles are present on the 'm' line, the profile
qualified by this attribute is the first qualified by this attribute is the first
profile. If a single profile that has been selected for a connection profile. If a single profile that has been selected for a connection
is indicated in the 'm' line, the 'dsel' attribute qualifies the is indicated in the 'm' line, the 'dsel' attribute qualifies the
use, for voiceband data service, of codecs within that profile. use, for voiceband data service, of codecs within that profile.
With most of the encoding names in Figure 2, the packet length
and packetization period can be derived from each other. One of them
can be set to "-" without a loss of information. There are some
exceptions such as the IANA-registered encoding names G723, DVI4 and
L16 for which this is not true. Therefore, there is a need to
retain both the packet length and packetization period in the
definition of the 'dsel' line.
5.6.10 The 'fsel' attribute 5.6.10 The 'fsel' attribute
The 'fsel' attribute indicates a prioritized list of The 'fsel' attribute indicates a prioritized list of
one or more 3-tuples for facsimile service. If an 'fsel' line one or more 3-tuples for facsimile service. If an 'fsel' line
Rajesh Kumar, Mohamed Mostafa. 39
is present, any 'dsel' line with <fxIncl> set to "on" in the session is present, any 'dsel' line with <fxIncl> set to "on" in the session
description must be consistent with it. In this case, description must be consistent with it. In this case,
an error event is generated in the case of inconsistency. an error event is generated in the case of inconsistency.
Each 3-tuple indicates a codec, an optional packet length and an Each 3-tuple indicates a codec, an optional packet length and an
optional packetization period. This complements the 'm' line information optional packetization period. This complements the 'm' line information
and should be consistent with it. and should be consistent with it.
The 'fsel' line is structured as follows: The 'fsel' line is structured as follows:
a=fsel:<encodingName #1> <packetLength #1><packetTime #1> a=fsel:<encodingName #1> <packetLength #1><packetTime #1>
skipping to change at line 1926 skipping to change at line 2061
be set to "-" when not needed. Also, the entire 'fsel' media attribute be set to "-" when not needed. Also, the entire 'fsel' media attribute
line can be omitted when not needed. line can be omitted when not needed.
For example, For example,
a=fsel:FXDMOD-3 - - a=fsel:FXDMOD-3 - -
indicates demodulation and remodulation of ITU-T group 3 fax at the indicates demodulation and remodulation of ITU-T group 3 fax at the
gateway. gateway.
a=fsel:PCMU 40 5 G726-32 20 5 a=fsel:PCMU 40 5000 G726-32 20 5000
indicates a first and second preference of Mu-law PCM and 32 kbps indicates a first and second preference of Mu-law PCM and 32 kbps
Rajesh Kumar, Mohamed Mostafa. 32
ADPCM as the facsimile encoding scheme. The packet length ADPCM as the facsimile encoding scheme. The packet length
and the packetization interval associated with G726-32 are 20 octets and and the packetization interval associated with G726-32 are 20 octets and
5 ms respectively. For PCMU, they are 40 octets and 5 ms respectively. 5 ms respectively. For PCMU, they are 40 octets and 5 ms respectively.
This media attribute line can be used in ATM as well as non-ATM contexts. This media attribute line can be used in ATM as well as non-ATM contexts.
Within the ATM context, it can be applied to the AAL1, AAL2 and AAL5 Within the ATM context, it can be applied to the AAL1, AAL2 and AAL5
adaptations. The <packetLength> and <packetTime> are not meaningful adaptations. The <packetLength> and <packetTime> are not meaningful
in the AAL1 case and should be set to "-". In the AAL2 case, in the AAL1 case and should be set to "-". In the AAL2 case,
this line determines the use of some or all of the rows in this line determines the use of some or all of the rows in
a given profile table. If multiple 3-tuples are present, they a given profile table. If multiple 3-tuples are present, they
can indicate a hierarchical assignment of some rows in that can indicate a hierarchical assignment of some rows in that
profile to facsimile service e.g. row A preferred to row B etc. profile to facsimile service e.g. row A preferred to row B etc.
If multiple profiles are present on the 'm' line, the profile If multiple profiles are present on the 'm' line, the profile
qualified by this attribute is the first qualified by this attribute is the first
profile. If a single profile that has been selected for a connection profile. If a single profile that has been selected for a connection
is indicated in the 'm' line, the 'fsel' attribute qualifies the is indicated in the 'm' line, the 'fsel' attribute qualifies the
use, for facsimile service, of codecs within that profile. use, for facsimile service, of codecs within that profile.
5.6.11 The 'capability' attribute With most of the encoding names in Figure 2, the packet length
and packetization period can be derived from each other. One of them
Rajesh Kumar, Mohamed Mostafa. 40
can be set to "-" without a loss of information. There are some
exceptions such as the IANA-registered encoding names G723, DVI4 and
L16 for which this is not true. Therefore, there is a need to
retain both the packet length and packetization period in the
definition of the 'fsel' line.
5.6.11 The 'codecconfig' attribute
When present, the 'codecconfig' attribute is used to represent the
contents of the single codec information element (IE) defined in [57].
The contents of this IE are: a single-octet Organizational Identifier
(OID) field, followed by a single-octet Codec Type field, followed by
zero or more octets of a codec configuration bit-map. The semantics of
the codec configuration bit-map are specific to the organization
[57, 58]. The 'codecconfig' attribute is represented as follows:
a=codecconfig:<q7655scc>
The <q7655scc> (Q.765.5 single codec IE contents) parameter is
represented as a string of hex digits. The number of hex digits is
even (range 4 -32). The "0x" prefix shall be omitted since this value
is always hexadecimal. As with other hex values [Section 2.2],
digits to the left are more significant than digits to the right.
Leading zeros shall not be omitted.
An example of the use of this media attribute is:
a=codecconfig:01080C
The first octet indicates an Organizational Identifier of 0x01
(the ITU-T). Using ITU Q.765.5 [57], the second octet (0x08) indicates
a codec type of G.726 (ADPCM). The last octet, 0x0C indicates that
16 kbps and 24 kbps rates are NOT supported, while the 32 kbps and
40 kbps rates ARE supported.
5.6.12 The 'isup_usi' attribute
When present, the 'isup_usi' attribute is used to represent the
'User Information Layer 1 protocol' field within the bearer
capability information element defined in Section 4.5.5 of [59], and
reiterated as the user service information element (IE) in Section 3.57
of [60]. The 'User Information Layer 1 protocol' field consists of
the five least significant bits of Octet 5 of this information
element. This field is represented by the USI property in Section C.9
of the Megaco/H.248 protocol [26].
Within SDP, the 'isup_usi' attribute is represented as follows:
a=isup_usi:<isupUsi>
The <isupUsi> parameter is represented as a string of two hex
Rajesh Kumar, Mohamed Mostafa. 41
digits. The "0x" prefix shall be omitted since this value
is always hexadecimal. As with other hex values [Section 2.2],
digits to the left are more significant than digits to the right.
These hex digits are constructed from an octet with three leading
'0' bits and last five bits equal to the 'User Information Layer
1 protocol' field described above. As specified in [59] and [26],
bit 5 of this field is the most significant bit. The resulting values
of the <isupUsi> parameter are as follows:
VALUE MEANING
0x01 CCITT standardized rate adaption V.110 and X.30
0x02 Recommendation G.711 Mu-law
0x03 Recommendation G.711 A-law
0x04 Recommendation G.721 32 kbps ADPCM and Recommendation I.460
0x05 Recommendations H.221 and H.242
0x06 Recommendation H.223 and H.245
0x07 Non-ITU-T standardized rate adaption
0x08 ITU-T standardized rate adaption V.120
0x09 CCITT standardized rate adaption X.31 HDLC flag stuffing
5.6.13 The 'capability' attribute
When present, the 'capability' attribute indicates the ATM Transfer When present, the 'capability' attribute indicates the ATM Transfer
Capability described in ITU I.371 [28], equivalent to the ATM Service Capability described in ITU I.371 [28], equivalent to the ATM Service
Category described in the UNI 4.1 Traffic Management specification [6]. Category described in the UNI 4.1 Traffic Management specification [6].
The 'capability' media attribute line is structured in one of The 'capability' media attribute line is structured in one of
the following ways: the following ways:
a=capability:<asc> <subtype> a=capability:<asc> <subtype>
skipping to change at line 1979 skipping to change at line 2189
Some applications might use non-standard <atc> and <asc> values not Some applications might use non-standard <atc> and <asc> values not
listed above. Equipment designers will need to agree on the meaning and listed above. Equipment designers will need to agree on the meaning and
implications of non-standard transfer capabilities / service capabilities. implications of non-standard transfer capabilities / service capabilities.
The <subtype> field essentially serves as a subscript to the <asc> The <subtype> field essentially serves as a subscript to the <asc>
and <atc> fields. In general, it can take on any integer value, or the and <atc> fields. In general, it can take on any integer value, or the
"-" value indicating that it does not apply or that the underlying data is "-" value indicating that it does not apply or that the underlying data is
to be known by other means, such as provisioning. to be known by other means, such as provisioning.
Rajesh Kumar, Mohamed Mostafa. 42
The following combinations are recognized in the ATMF and ITU The following combinations are recognized in the ATMF and ITU
specifications: specifications:
Rajesh Kumar, Mohamed Mostafa. 33
<asc>/<atc> <subtype> Meaning <asc>/<atc> <subtype> Meaning
nrt-VBR 1 nrt-VBR.1 nrt-VBR 1 nrt-VBR.1
nrt-VBR 2 nrt-VBR.2 nrt-VBR 2 nrt-VBR.2
nrt-VBR 3 nrt-VBR.3 nrt-VBR 3 nrt-VBR.3
rt-VBR 1 rt-VBR.1 rt-VBR 1 rt-VBR.1
rt-VBR 2 rt-VBR.2 rt-VBR 2 rt-VBR.2
rt-VBR 3 rt-VBR.3 rt-VBR 3 rt-VBR.3
UBR 1 UBR.1 UBR 1 UBR.1
UBR 2 UBR.2 UBR 2 UBR.2
skipping to change at line 2007 skipping to change at line 2217
SBR 3 SBR3 SBR 3 SBR3
It is beyond the scope of this specification to examine the It is beyond the scope of this specification to examine the
equivalence of some of the ATMF and ITU definitions. These need to equivalence of some of the ATMF and ITU definitions. These need to
be recognized from the ATMF and ITU source specifications and exploited, be recognized from the ATMF and ITU source specifications and exploited,
as much as possible, to simplify ATM node design. as much as possible, to simplify ATM node design.
When the bearer connection is a single AAL2 CID connection within a When the bearer connection is a single AAL2 CID connection within a
multiplexed AAL2 VC, the 'capability' attribute does not apply. multiplexed AAL2 VC, the 'capability' attribute does not apply.
5.6.12 The 'qosClass' attribute 5.6.14 The 'qosClass' attribute
When present, the 'qosClass' attribute indicates the QoS class When present, the 'qosClass' attribute indicates the QoS class
specified in ITU I.2965.1 [34]. specified in ITU I.2965.1 [34].
The 'qosClass' media attribute line is structured as follows: The 'qosClass' media attribute line is structured as follows:
a=qosClass:<qosClass> a=qosClass:<qosClass>
Here, <qosClass> is an integer in the range 0 - 5. Here, <qosClass> is an integer in the range 0 - 5.
<qosClass> Meaning <qosClass> Meaning
0 Default QoS 0 Default QoS
1 Stringent 1 Stringent
2 Tolerant 2 Tolerant
3 Bi-level 3 Bi-level
4 Unbounded 4 Unbounded
5 Stringent bi-level 5 Stringent bi-level
5.6.13 The 'bcob' attribute 5.6.15 The 'bcob' attribute
When present, the 'bcob' attribute represents the broadband When present, the 'bcob' attribute represents the broadband
connection oriented bearer class defined in ITU Q.2961.2 [33]. The connection oriented bearer class defined in ITU Q.2961.2 [33]. The
'bcob' media attribute line is structured as follows: 'bcob' media attribute line is structured as follows:
Rajesh Kumar, Mohamed Mostafa. 43
a=bcob:<bcob> a=bcob:<bcob>
Here, <bcob> is the decimal or hex representation of a 5-bit field. Here, <bcob> is the decimal or hex representation of a 5-bit field.
Currently, all values are unused and reserved with the following Currently, all values are unused and reserved with the following
exceptions: exceptions:
Rajesh Kumar, Mohamed Mostafa. 34
<bcob> Meaning <bcob> Meaning
1 BCOB-A 1 BCOB-A
3 BCOB-C 3 BCOB-C
16 BCOB-X 16 BCOB-X
24 BCOB-VP (transparent VP service) 24 BCOB-VP (transparent VP service)
5.6.14 The 'stc' attribute 5.6.16 The 'stc' attribute
When present, the 'stc' attribute represents susceptibility When present, the 'stc' attribute represents susceptibility
to clipping. The 'stc' media attribute line is structured as to clipping. The 'stc' media attribute line is structured as
follows: follows:
a=stc:<stc> a=stc:<stc>
Here, <stc> is the decimal equivalent of a 2-bit field. Currently, Here, <stc> is the decimal equivalent of a 2-bit field. Currently,
all values are unused and reserved with the following exceptions: all values are unused and reserved with the following exceptions:
<stc> value Binary Equivalent Meaning <stc> value Binary Equivalent Meaning
0 00 Not susceptible to clipping 0 00 Not susceptible to clipping
1 01 Susceptible to clipping 1 01 Susceptible to clipping
5.6.15 The 'upcc' attribute 5.6.17 The 'upcc' attribute
When present, the 'upcc' attribute represents the user plane When present, the 'upcc' attribute represents the user plane
connection configuration. The 'upcc' media attribute line is connection configuration. The 'upcc' media attribute line is
structured as follows: structured as follows:
a=upcc:<upcc> a=upcc:<upcc>
Here, <upcc> is the decimal equivalent of a 2-bit field. Currently, Here, <upcc> is the decimal equivalent of a 2-bit field. Currently,
all values are unused and reserved with the following exceptions: all values are unused and reserved with the following exceptions:
<upcc> value Binary Equivalent Meaning <upcc> value Binary Equivalent Meaning
0 00 Point to point 0 00 Point to point
1 01 Point to multipoint 1 01 Point to multipoint
5.6.16 The 'atmQOSfparms' and 'atmQOSbparms' attributes 5.6.18 The 'atmQOSfparms' and 'atmQOSbparms' attributes
When present, the 'atmQOSfparms' and 'atmQOSbparms' When present, the 'atmQOSfparms' and 'atmQOSbparms'
attributes are used to describe certain key ATM QoS parameters attributes are used to describe certain key ATM QoS parameters
in the forward and backward directions respectively. See Section in the forward and backward directions respectively. See Section
Rajesh Kumar, Mohamed Mostafa. 44
2.3 for a definition of the terms 'forward' and 'backward'. 2.3 for a definition of the terms 'forward' and 'backward'.
The 'atmQOSfparms' and 'atmQOSbparms' media attribute lines The 'atmQOSfparms' and 'atmQOSbparms' media attribute lines
are structured as follows: are structured as follows:
a=atmQOSfparms: <cdvType><acdv><ccdv><actd><cctd><aclr> a=atmQOSfparms: <cdvType><acdv><ccdv><actd><cctd><aclr>
a=atmQOSbparms: <cdvType><acdv><ccdv><actd><cctd><aclr> a=atmQOSbparms: <cdvType><acdv><ccdv><actd><cctd><aclr>
The <cdvType> parameter can take on the string values of The <cdvType> parameter can take on the string values of
"PP" and "2P". These refer to the peak-to-peak and two-point "PP" and "2P". These refer to the peak-to-peak and two-point
CDV as defined in UNI 4.0 [5] and ITU Q.2965.2 [35] respectively. CDV as defined in UNI 4.0 [5] and ITU Q.2965.2 [35] respectively.
Rajesh Kumar, Mohamed Mostafa. 35
The CDV parameters, <acdv> and <ccdv>, refer to the acceptable The CDV parameters, <acdv> and <ccdv>, refer to the acceptable
and cumulative CDVs respectively. These are expressed in units and cumulative CDVs respectively. These are expressed in units
of microseconds and represented as the decimal equivalent of microseconds and represented as the decimal equivalent
of a 24-bit field. These use the cell loss ratio, <aclr>, as the of a 24-bit field. These use the cell loss ratio, <aclr>, as the
"alpha" quantiles defined in the ATMF TM 4.1 specification [6] "alpha" quantiles defined in the ATMF TM 4.1 specification [6]
and in ITU I.356 [47]. and in ITU I.356 [47].
The CTD parameters, <actd> and <cctd>, refer to the acceptable and The CTD parameters, <actd> and <cctd>, refer to the acceptable and
cumulative CTDs respectively in milliseconds. These are represented as cumulative CTDs respectively in milliseconds. These are represented as
the decimal equivalents of 16-bit fields. These parameters are the decimal equivalents of 16-bit fields. These parameters are
skipping to change at line 2137 skipping to change at line 2348
backward acceptable peak-to-peak CDV of 4.675 ms, forward backward acceptable peak-to-peak CDV of 4.675 ms, forward
cumulative peak-to-peak CDV of 3.455 ms, a backward cumulative cumulative peak-to-peak CDV of 3.455 ms, a backward cumulative
peak-to-peak CDV of 2.155 ms, a forward acceptable maximum peak-to-peak CDV of 2.155 ms, a forward acceptable maximum
cell transfer delay of 32 ms, a backward acceptable maximum cell transfer delay of 32 ms, a backward acceptable maximum
cell transfer delay of 18 ms, an unspecified forward cumulative cell transfer delay of 18 ms, an unspecified forward cumulative
cell transfer delay, an unspecified backward cumulative cell transfer cell transfer delay, an unspecified backward cumulative cell transfer
delay, a forward cell loss ratio of 10 raised to minus 11 and a delay, a forward cell loss ratio of 10 raised to minus 11 and a
backward cell loss ratio of 10 to the minus 12. backward cell loss ratio of 10 to the minus 12.
In certain applications (such as SIP-based applications), an SDP In certain applications (such as SIP-based applications), an SDP
Rajesh Kumar, Mohamed Mostafa. 45
descriptor might have both the atmQOSfparms and atmQOSbparms descriptor might have both the atmQOSfparms and atmQOSbparms
attributes. In other applications (such as Megaco-based applications), attributes. In other applications (such as Megaco-based applications),
the remote descriptor can have the atmQOSfparms attribute the remote descriptor can have the atmQOSfparms attribute, and
while the local descriptor can have the atmQOSbparms attribute. the local descriptor can have the atmQOSbparms attribute.
5.6.17 The 'aal2QOSfparms' and 'aal2QOSbparms' attributes
It is recognized that means of characterizing impairments in AAL2
packet streams are not clearly defined at this time. These AAL2 media
attributes lines will constructed along the line of the 'atmQOSfparms'
and 'atmQOSbparms' attribute lines. At present, their names serve
as placeholders.
5.6.18 The 'atmFtrfcDesc' and 'atmBtrfcDesc' attributes 5.6.19 The 'atmFtrfcDesc' and 'atmBtrfcDesc' attributes
When present, the 'atmFtrfcDesc' and 'atmBtrfcDesc' attributes When present, the 'atmFtrfcDesc' and 'atmBtrfcDesc' attributes
are used to indicate ATM traffic descriptor parameters in the are used to indicate ATM traffic descriptor parameters in the
forward and backward directions respectively. See Section 2.3 for a forward and backward directions respectively. See Section 2.3 for a
definition of the terms 'forward' and 'backward'. definition of the terms 'forward' and 'backward'.
Rajesh Kumar, Mohamed Mostafa. 36
The 'atmFtrfcDesc' and 'atmBtrfcDesc' media attribute lines The 'atmFtrfcDesc' and 'atmBtrfcDesc' media attribute lines
are structured as follows: are structured as follows:
a=atmFtrfcDesc:<clpLvl> <pcr><scr><mbs><cdvt><mcr><mfs><fd><te> a=atmFtrfcDesc:<clpLvl> <pcr><scr><mbs><cdvt><mcr><mfs><fd><te>
a=atmBtrfcDesc:<clpLvl> <pcr><scr><mbs><cdvt><mcr><mfs><fd><te> a=atmBtrfcDesc:<clpLvl> <pcr><scr><mbs><cdvt><mcr><mfs><fd><te>
If any of these parameters in these media attribute lines is not If any of these parameters in these media attribute lines is not
specified, is inapplicable or is implied, then it is set to "-". specified, is inapplicable or is implied, then it is set to "-".
The <clpLvl> (CLP level) parameter indicates whether the rates and The <clpLvl> (CLP level) parameter indicates whether the rates and
skipping to change at line 2180 skipping to change at line 2384
"0", "0+1" and "-". If rates and bursts for both <clpLvl> values are to "0", "0+1" and "-". If rates and bursts for both <clpLvl> values are to
be described, then it is necessary to use two separate be described, then it is necessary to use two separate
media attribute lines for each direction in the same session media attribute lines for each direction in the same session
descriptor. If the <clpLvl> parameter is set to "-", then it descriptor. If the <clpLvl> parameter is set to "-", then it
implies that the CLP parameter is known by other means such as default, implies that the CLP parameter is known by other means such as default,
MIB provisioning etc. MIB provisioning etc.
The meaning, units and applicability of the remaining parameters The meaning, units and applicability of the remaining parameters
are per the ATMF TM 4.1 specification [6] and are reiterated below: are per the ATMF TM 4.1 specification [6] and are reiterated below:
Rajesh Kumar, Mohamed Mostafa. 46
PARAMETER MEANING UNITS APPLICABILITY PARAMETER MEANING UNITS APPLICABILITY
<pcr> PCR Cells/ CBR, rt-VBR, nrt-VBR, <pcr> PCR Cells/ CBR, rt-VBR, nrt-VBR,
second ABR, UBR, GFR; second ABR, UBR, GFR;
CLP=0,0+1 CLP=0,0+1
<scr> SCR Cells/ rt-VBR, nrt-VBR; <scr> SCR Cells/ rt-VBR, nrt-VBR;
second CLP=0,0+1 second CLP=0,0+1
<mbs> MBS Cells rt-VBR, nrt-VBR, <mbs> MBS Cells rt-VBR, nrt-VBR,
GFR; GFR;
CLP=0,0+1 CLP=0,0+1
skipping to change at line 2215 skipping to change at line 2421
<te> CLP "on"/"off" CBR, rt-VBR, nrt-VBR, <te> CLP "on"/"off" CBR, rt-VBR, nrt-VBR,
tagging ABR, UBR, GFR; tagging ABR, UBR, GFR;
Enabled CLP=0 Enabled CLP=0
<fd> indicates that frame discard is permitted. It can take on the string <fd> indicates that frame discard is permitted. It can take on the string
values of "on" or "off". Note that, in the GFR case, frame discard values of "on" or "off". Note that, in the GFR case, frame discard
is always enabled. Hence, this subparameter can be set to "-" in is always enabled. Hence, this subparameter can be set to "-" in
the case of GFR. Since the <fd> parameter is independent the case of GFR. Since the <fd> parameter is independent
of CLP, it is meaningful in the case when <clpLvl> = "0+1". of CLP, it is meaningful in the case when <clpLvl> = "0+1".
Rajesh Kumar, Mohamed Mostafa. 37
It should be set to "-" for the case when <clpLvl> = "0". It should be set to "-" for the case when <clpLvl> = "0".
<te> (tag enable) indicates that CLP tagging is allowed. <te> (tag enable) indicates that CLP tagging is allowed.
These can take on the string values of "on" or "off". These can take on the string values of "on" or "off".
Since the <te> parameter applies only to cells with Since the <te> parameter applies only to cells with
a CLP of 0, it is meaningful in the case when <clpLvl> = "0". a CLP of 0, it is meaningful in the case when <clpLvl> = "0".
It should be set to "-" for the case when <clpLvl> = "0+1". It should be set to "-" for the case when <clpLvl> = "0+1".
An example use of these media attribute lines for an rt-VBR, An example use of these media attribute lines for an rt-VBR,
single-CID AAL2 voice VC is: single-CID AAL2 voice VC is:
Rajesh Kumar, Mohamed Mostafa. 47
a=atmFtrfcDesc:0+1 200 100 20 - - - on - a=atmFtrfcDesc:0+1 200 100 20 - - - on -
a=atmFtrfcDesc:0 200 80 15 - - - - off a=atmFtrfcDesc:0 200 80 15 - - - - off
a=atmBtrfcDesc:0+1 200 100 20 - - - on - a=atmBtrfcDesc:0+1 200 100 20 - - - on -
a=atmBtrfcDesc:0 200 80 15 - - - - off a=atmBtrfcDesc:0 200 80 15 - - - - off
This implies a forward and backward PCR of 200 cells per second This implies a forward and backward PCR of 200 cells per second
all cells regardless of CLP, forward and backward PCR of 200 cells all cells regardless of CLP, forward and backward PCR of 200 cells
per second for cells with CLP=0, a forward and backward SCR of 100 per second for cells with CLP=0, a forward and backward SCR of 100
cells per second for all cells regardless of CLP, a forward and cells per second for all cells regardless of CLP, a forward and
backward SCR of 80 cells per second for cells with CLP=0, backward SCR of 80 cells per second for cells with CLP=0,
skipping to change at line 2251 skipping to change at line 2456
and an MCR and MFS which are unspecified because they are and an MCR and MFS which are unspecified because they are
inapplicable. Frame discard is enabled in both the forward and inapplicable. Frame discard is enabled in both the forward and
backward directions. Tagging is not enabled in either direction. backward directions. Tagging is not enabled in either direction.
The <pcr>, <scr>, <mbs>, <cdvt>, <mcr> and <mfs> are represented as The <pcr>, <scr>, <mbs>, <cdvt>, <mcr> and <mfs> are represented as
decimal integers, with range as defined in Section 6. decimal integers, with range as defined in Section 6.
In certain applications (such as SIP-based applications), an SDP In certain applications (such as SIP-based applications), an SDP
descriptor might have both the atmFtrfcDesc and atmBtrfcDesc descriptor might have both the atmFtrfcDesc and atmBtrfcDesc
attributes. In other applications (such as Megaco-based applications), attributes. In other applications (such as Megaco-based applications),
the remote descriptor can have the atmFtrfcDesc attribute the remote descriptor can have the atmFtrfcDesc attribute, and
while the local descriptor can have the atmBtrfcDesc attribute. the local descriptor can have the atmBtrfcDesc attribute.
5.6.19 The 'aal2FtrfcDesc' and 'aal2BtrfcDesc' attributes
It might be meaningful to construct descriptors for traffic
at the AAL2 packet (subcell) level. These can tentatively be
named the 'aal2FtrfcDesc' and 'aal2BtrfcDesc' attributes
When constructed, these can be similar in some aspects to the
'atmFtrfcDesc' and 'atmBtrfcDesc' attributes. Until then, these
names serve as placeholders.
5.6.20 The 'abrFparms' and 'abrBparms' attributes 5.6.20 The 'abrFparms' and 'abrBparms' attributes
When present, the 'abrFparms' and 'abrBparms' attributes When present, the 'abrFparms' and 'abrBparms' attributes
are used to indicate the 'additional' ABR parameters specified are used to indicate the 'additional' ABR parameters specified
in the UNI 4.0 signaling specification [5]. These refer to the in the UNI 4.0 signaling specification [5]. These refer to the
forward and backward directions respectively. See Section forward and backward directions respectively. See Section
2.3 for a definition of the terms 'forward' and 'backward'. 2.3 for a definition of the terms 'forward' and 'backward'.
The 'abrFparms' and 'abrBparms' media attribute lines are structured The 'abrFparms' and 'abrBparms' media attribute lines are structured
as follows: as follows:
a=abrFparms:<nrm><trm><cdf><adtf> a=abrFparms:<nrm><trm><cdf><adtf>
a=abrBparms:<nrm><trm><cdf><adtf> a=abrBparms:<nrm><trm><cdf><adtf>
These parameters are mapped into the ABR service parameters in These parameters are mapped into the ABR service parameters in
Rajesh Kumar, Mohamed Mostafa. 38
[6] in the manner described below. These parameters can be [6] in the manner described below. These parameters can be
represented in SDP as decimal integers, with fractions permitted represented in SDP as decimal integers, with fractions permitted
for some. Details of the meaning, units and applicability of for some. Details of the meaning, units and applicability of
these parameters are in [5] and [6]. these parameters are in [5] and [6].
If any of these parameters in the 'abrFparms' or 'abrBparms' media If any of these parameters in the 'abrFparms' or 'abrBparms' media
attribute lines is not specified, is inapplicable or is implied, attribute lines is not specified, is inapplicable or is implied,
then it is set to "-". then it is set to "-".
In SDP, these parameters are represented as the decimal or hex In SDP, these parameters are represented as the decimal or hex
equivalent of the binary fields mentioned below. equivalent of the binary fields mentioned below.
Rajesh Kumar, Mohamed Mostafa. 48
+-----------+----------------------------------+-----------------------+ +-----------+----------------------------------+-----------------------+
| PARAMETER | MEANING | FIELD SIZE | | PARAMETER | MEANING | FIELD SIZE |
+-----------+----------------------------------+-----------------------+ +-----------+----------------------------------+-----------------------+
| <nrm> | Maximum number of cells per | 3 bits | | <nrm> | Maximum number of cells per | 3 bits |
| | forward Resource Management cell | | | | forward Resource Management cell | |
+-----------+----------------------------------+-----------------------+ +-----------+----------------------------------+-----------------------+
| <trm> | Maximum time between | 3 bits | | <trm> | Maximum time between | 3 bits |
| | forward Resource Management cells| | | | forward Resource Management cells| |
+-----------+----------------------------------+-----------------------+ +-----------+----------------------------------+-----------------------+
| <cdf> | Cutoff Decrease Factor | 3 bits | | <cdf> | Cutoff Decrease Factor | 3 bits |
+-----------+----------------------------------+-----------------------+ +-----------+----------------------------------+-----------------------+
| <adtf> | Allowed Cell Rate Decrease | 10 bits | | <adtf> | Allowed Cell Rate Decrease | 10 bits |
| | Time Factor | | | | Time Factor | |
+-----------+----------------------------------+-----------------------+ +-----------+----------------------------------+-----------------------+
In certain applications (such as SIP-based applications), an SDP In certain applications (such as SIP-based applications), an SDP
descriptor might have both the abrFparms and abrBparms attributes. descriptor might have both the abrFparms and abrBparms attributes.
In other applications (such as Megaco-based applications), the In other applications (such as Megaco-based applications), the
remote descriptor can have the abrFparms attribute while the local remote descriptor can have the abrFparms attribute, and the local
descriptor can have the abrBparms attribute. descriptor can have the abrBparms attribute.
5.6.21 The 'clkrec' attribute 5.6.21 The 'clkrec' attribute
When present, the 'clkrec' attribute is used to indicate When present, the 'clkrec' attribute is used to indicate
the clock recovery method. This attribute is meaningful in the the clock recovery method. This attribute is meaningful in the
case of AAL1 unstructured data transfer (UDT). The format of the case of AAL1 unstructured data transfer (UDT). The format of the
'clkrec' media attribute line is as follows: 'clkrec' media attribute line is as follows:
a=clkrec:<clkrec> a=clkrec:<clkrec>
skipping to change at line 2341 skipping to change at line 2536
forward error correction. Currently, there exists a forward error forward error correction. Currently, there exists a forward error
correction method defined for AAL1 in ITU I.363.1 [10]. The format of the correction method defined for AAL1 in ITU I.363.1 [10]. The format of the
'fec' media attribute line is as follows: 'fec' media attribute line is as follows:
a=fec:<fecEnable> a=fec:<fecEnable>
The <fecEnable> flag indicates the presence of absence of Forward The <fecEnable> flag indicates the presence of absence of Forward
Error Correction. It can take on the string values of "NULL", Error Correction. It can take on the string values of "NULL",
"LOSS_SENSITIVE" and "DELAY_SENSITIVE". An "NULL" value implies disabling "LOSS_SENSITIVE" and "DELAY_SENSITIVE". An "NULL" value implies disabling
this capability. FEC can be enabled differently for delay-sensitive this capability. FEC can be enabled differently for delay-sensitive
Rajesh Kumar, Mohamed Mostafa. 39
and loss-sensitive connections. and loss-sensitive connections.
Rajesh Kumar, Mohamed Mostafa. 49
5.6.23 The 'prtfl' attribute 5.6.23 The 'prtfl' attribute
When present, the 'prtfl' attribute is used to indicate the fill When present, the 'prtfl' attribute is used to indicate the fill
level of cells. When this attribute is absent, then level of cells. When this attribute is absent, then
other means (such as provisionable defaults) are used to determine other means (such as provisionable defaults) are used to determine
the presence and level of partial fill. the presence and level of partial fill.
This attribute indicates the number of non-pad payload This attribute indicates the number of non-pad payload
octets, not including any AAL SAR or convergence sublayer octets. For octets, not including any AAL SAR or convergence sublayer octets. For
example, in some AAL1 applications that use partially filled cells with example, in some AAL1 applications that use partially filled cells with
skipping to change at line 2397 skipping to change at line 2592
When present, the 'bearerType' attribute is used to indicate When present, the 'bearerType' attribute is used to indicate
whether the underlying bearer is an ATM PVC/SPVC, an ATM SVC, whether the underlying bearer is an ATM PVC/SPVC, an ATM SVC,
or an AAL2 CID connection within an existing ATM PVC/SPVC. or an AAL2 CID connection within an existing ATM PVC/SPVC.
Additionally, for ATM SVCs and AAL2 CID connections, the Additionally, for ATM SVCs and AAL2 CID connections, the
'bearerType' attribute can be used to indicate whether the 'bearerType' attribute can be used to indicate whether the
media gateway initiates connection set-up via bearer signaling media gateway initiates connection set-up via bearer signaling
(Q.2931-based or Q.2630.1 based). The format of the 'bearerType' (Q.2931-based or Q.2630.1 based). The format of the 'bearerType'
media attribute line is as follows: media attribute line is as follows:
Rajesh Kumar, Mohamed Mostafa. 50
a=bearerType: <bearerType> <localInititiation> a=bearerType: <bearerType> <localInititiation>
The <bearerType> field can take on the following string values: The <bearerType> field can take on the following string values:
"PVC", "SVC", "CID", with semantics as defined above. Here, "PVC" "PVC", "SVC", "CID", with semantics as defined above. Here, "PVC"
includes both the PVC and SPVC cases. includes both the PVC and SPVC cases.
In the case when the underlying bearer is a PVC/SPVC, or a CID In the case when the underlying bearer is a PVC/SPVC, or a CID
Rajesh Kumar, Mohamed Mostafa. 40
assigned by the MGC rather than through bearer signaling, the assigned by the MGC rather than through bearer signaling, the
<localInititiation> flag can be omitted or set to "-". In the <localInititiation> flag can be omitted or set to "-". In the
case when bearer signaling is used, this flag can be omitted case when bearer signaling is used, this flag can be omitted
when it is known by default or by other means whether the media when it is known by default or by other means whether the media
gateway initiates the connection set-up via bearer signaling. Only gateway initiates the connection set-up via bearer signaling. Only
when this is to be indicated explicitly that the <localInititiation> when this is to be indicated explicitly that the <localInititiation>
flag takes on the values of "on" or "off". An "on" value indicates flag takes on the values of "on" or "off". An "on" value indicates
that the media gateway is responsible for initiating connection set-up that the media gateway is responsible for initiating connection set-up
via bearer signaling (SVC signaling or Q.2630.1 signaling), via bearer signaling (SVC signaling or Q.2630.1 signaling),
an "off" value indicates otherwise. an "off" value indicates otherwise.
skipping to change at line 2450 skipping to change at line 2644
5.6.26 The 'sbc' attribute 5.6.26 The 'sbc' attribute
The 'sbc' media attribute line denotes the subchannel count and The 'sbc' media attribute line denotes the subchannel count and
is meaningful only in the case of n x 64 clear channel communication. is meaningful only in the case of n x 64 clear channel communication.
A clear n x 64 channel can use AAL1 (ATM forum af-vtoa-78) or AAL2 A clear n x 64 channel can use AAL1 (ATM forum af-vtoa-78) or AAL2
adaptation (ITU I.366.2). Although no such standard definition exists, adaptation (ITU I.366.2). Although no such standard definition exists,
it is also possible to use AAL5 for this purpose. An n x 64 clear channel it is also possible to use AAL5 for this purpose. An n x 64 clear channel
is represented by the encoding names of "X-CCD" and "X-CCD-CAS" in is represented by the encoding names of "X-CCD" and "X-CCD-CAS" in
Table 2. Table 2.
Rajesh Kumar, Mohamed Mostafa. 51
The format of the 'sbc' media attribute line is as follows: The format of the 'sbc' media attribute line is as follows:
a=sbc:<sbc> a=sbc:<sbc>
Here, <sbc> can be expressed as a decimal or hex integer. This Here, <sbc> can be expressed as a decimal or hex integer. This
attribute indicates the number of DS0s in a T1 or E1 frame that are attribute indicates the number of DS0s in a T1 or E1 frame that are
aggregated for transmitting clear channel data. For T1-based aggregated for transmitting clear channel data. For T1-based
applications, it can take on integral values in the inclusive range applications, it can take on integral values in the inclusive range
[1...24]. For E1-based applications, it can take on integral values in [1...24]. For E1-based applications, it can take on integral values in
the inclusive range [1...31]. When omitted, other means are to be used the inclusive range [1...31]. When omitted, other means are to be used
to determine the subchannel count. to determine the subchannel count.
Use of the 'sbc' attribute provides a direct way to indicate the
number of 64 kbps subchannels bundled into an n x 64 clear
channel. An alternate mechanism to indicate this exists within
the SDP bandwidth information, or 'b', line [1]. In this case,
instead of specifying the number of subchannels, the aggregate
bandwidth in kbps is specified. The syntax of the 'b' line, copied
verbatim from [1], is as follows:
b=<modifier>:<bandwidth-value>
In the case of n x 64 clear channels, the <modifier> is assigned a
text string value of "AS", indicating that the 'b' line is application-
specific. The <bandwidth-value> parameter, which is a decimal number
indicating the bandwidth in kbps, is limited to one of the
following values in the n x 64 clear channel application context:
64, 128, 192, 256, 320, 384, 448, 512, 576, 640, 704, 768, 832,
896, 960, 1024, 1088, 1152, 1216, 1280, 1344, 1408, 1472, 1600,
1664, 1728, 1792, 1856, 1920, 1984
Thus, for n x 64 circuit mode data service,
a=sbc:6
is equivalent to
b=AS:384
The media attribute line
a=sbc:2
is equivalent to
b=AS:128
5.6.27 The 'fcpsSDUsize' and 'bcpsSDUsize' attributes 5.6.27 The 'fcpsSDUsize' and 'bcpsSDUsize' attributes
When present, the 'fcpsSDUsize' and 'bcpsSDUsize' attributes are used to When present, the 'fcpsSDUsize' and 'bcpsSDUsize' attributes are used to
indicate the maximum size of the CPCS SDU payload in the forward and indicate the maximum size of the CPCS SDU payload in the forward and
Rajesh Kumar, Mohamed Mostafa. 41 Rajesh Kumar, Mohamed Mostafa. 52
backward directions respectively. See section 2.3 for a definition of the backward directions respectively. See section 2.3 for a definition of the
terms 'forward' and 'backward'. The format of these media attribute lines is terms 'forward' and 'backward'. The format of these media attribute lines is
as follows: as follows:
a=fcpsSDUsize: <cpcs> a=fcpsSDUsize: <cpcs>
a=bcpsSDUsize: <cpcs> a=bcpsSDUsize: <cpcs>
The <cpcs> fields is a 16-bit integer that can be represented in The <cpcs> fields is a 16-bit integer that can be represented in
decimal or in hex. decimal or in hex.
The meaning and values of these fields are as follows: The meaning and values of these fields are as follows:
Application Field Meaning Values Application Field Meaning Values
AAL5 <cpcs> Maximum CPCS-SDU size 1- 65,535 AAL5 <cpcs> Maximum CPCS-SDU size 1- 65,535
AAL2 <cpcs> Maximum CPCS-SDU size 45 or 64 AAL2 <cpcs> Maximum CPCS-SDU size 45 or 64
In certain applications (such as SIP-based applications), an SDP In certain applications (such as SIP-based applications), an SDP
descriptor might have both the fcpsSDUsize and bcpsSDUsize descriptor might have both the fcpsSDUsize and bcpsSDUsize
attributes. In other applications (such as Megaco-based applications), attributes. In other applications (such as Megaco-based applications),
the remote descriptor can have the fcpsSDUsize attribute the remote descriptor can have the fcpsSDUsize attribute, and
while the local descriptor can have the bcpsSDUsize attribute. the local descriptor can have the bcpsSDUsize attribute.
5.6.28 The 'aal2CPS' attribute 5.6.28 The 'aal2CPS' attribute
When present, the 'aal2CPS' attribute is used to indicate describe When present, the 'aal2CPS' attribute is used to describe
parameters associated with the AAL2 CPS layer. parameters associated with the AAL2 CPS layer.
The format of the 'aal2CPS' media attribute line is as follows: The format of the 'aal2CPS' media attribute line is as follows:
a=aal2CPS:<cidCount> <timerCU> a=aal2CPS:<cidCount> <timerCU> <simplifiedCPS>
Each of these fields can be set to a "-" when the intention is to not Each of these fields can be set to a "-" when the intention is to not
specify them in an SDP descriptor. The <cidCount> integer can take on specify them in an SDP descriptor.
The <cidCount> integer can take on
values between 1 and 255. It represents the number of channels (CIDs) values between 1 and 255. It represents the number of channels (CIDs)
multiplexed into the AAL2 VCC. It can be represented in decimal or in hex. multiplexed into the AAL2 VCC. It can be represented in decimal or in hex.
Although the <cidCount> can take on values in the range 1-255, Although the <cidCount> can take on values in the range 1-255,
current applications do not allocate more than 248 CIDs per VC. current applications do not allocate more than 248 CIDs per VC.
This is because of reserved CID values [11]. The larger range This is because of reserved CID values [11]. The larger range
is permitted in the SDP to allow future and proprietary applications. is permitted in the SDP to allow future and proprietary applications.
The <timerCU> integer represents the "combined use" timerCU defined in The <timerCU> integer represents the "combined use" timerCU defined in
ITU I.363.2. This timer is represented as an integer number of microseconds. ITU I.363.2. This timer is represented as an integer number of microseconds.
5.6.29 The 'aal2sscs3661' attribute The <simplifiedCPS> parameter can be assigned the values "on" or "off". When
it is "on", the AAL2 CPS simplification described in [52] is adopted. Under
this simplification, each ATM cell contains exactly on AAL2 packet. If
When present, the 'aal2_SSCS_3661' attribute is used to indicate Rajesh Kumar, Mohamed Mostafa. 53
the options that pertain to the SSCS defined in ITU I.366.1 [12]. necessary, octets at the end of the cell are padded with zeros. Since the
This SSCS can be selected via the aalApp attribute defined below <timerCU> value in this context is always 0, it can be omitted.
or through the 'aal2_SSCS_3661' attribute. The format of this
5.6.29 The 'aal2sscs3661unassured' attribute
When present, the 'aal2sscs3661unassured' attribute is used to indicate
the options that pertain to the unassured transmission SSCS defined
in ITU I.366.1 [12]. This SSCS can be selected via the aalApp
attribute defined below, or by virtue of the presence of the
'aal2sscs3661unassured' attribute. The format of this
media attribute line is as follows: media attribute line is as follows:
a=aal2sscs3661:<adt> <ted> <fsssar> <bsssar> a=aal2sscs3661unassured: <ted> <fsssar> <bsssar>
Each of these fields can be set to a "-" when the intention is to not Each of these fields can be set to a "-" when the intention is to not
specify them in an SDP descriptor. specify them in an SDP descriptor.
The <adt> flag indicates the presence of absence of assured data The <ted> flag indicates the presence or absence of transmission
error detection as defined in I.366.1. It can be assigned the
Rajesh Kumar, Mohamed Mostafa. 42 values of "on" or "off". An "on" value indicates presence of
transfer as defined in I.366.1. The <ted> flag indicates the the capability.
presence of absence of transmission error detection as defined
in I.366.1. Each of these flags can take on the values of "on"
or "off". An "on" value indicates presence of the capability.
The <fsssar> and <bsssar> fields are 16-bit integers that The <fsssar> and <bsssar> fields are 24-bit integers that
can be represented in decimal or in hex. The meaning and values of can be represented in decimal or in hex. The meaning and values of
the <fsssar> and <bsssar> fields are as follows: the <fsssar> and <bsssar> fields are as follows:
Field Meaning Values Field Meaning Values
<fsssar> Maximum SSSAR-SDU size 1- 65,535 <fsssar> Maximum SSSAR-SDU size 1- 65,568
forward direction forward direction
<bsssar> Maximum SSSAR-SDU size 1- 65,535 <bsssar> Maximum SSSAR-SDU size 1- 65,568
backward direction backward direction
If present, the SSTED (Service-Specific Transmission Error
Detection) sublayer is above the SSSAR (Service-Specific Segmentation
and Reassembly) sublayer [12]. Since the maximum size of the
SSTED-SDUs can be derived from the maximum SSSAR-SDU size, it need
not be specified separately.
In certain applications (such as SIP-based applications), an SDP In certain applications (such as SIP-based applications), an SDP
descriptor might have an 'aal2sscs3661' media attribute line descriptor might have an 'aal2sscs3661unassured' media attribute line
with the <fsssar> and <bsssar> subparameters. In applications with the <fsssar> and <bsssar> subparameters. In other applications
(such as Megaco-based applications), the remote descriptor can have the (such as Megaco-based applications), the remote descriptor can have the
<fsssar> subparameter while the local descriptor can have the <fsssar> subparameter, and the local descriptor can have the
<bsssar> subparameter. <bsssar> subparameter.
5.6.30 The 'aal2sscs3662' attribute 5.6.30 The 'aal2sscs3661assured' attribute
When present, the 'aal2sscs3661assured' attribute is used to indicate
the options that pertain to the assured transmission SSCS defined
in ITU I.366.1 [12] on the basis of ITU Q.2110 [43]. This SSCS can be
Rajesh Kumar, Mohamed Mostafa. 54
selected via the aalApp attribute defined below, or by virtue
of the presence of the 'aal2sscs3661assured' attribute. The format of
this media attribute line is as follows:
a=aal2sscs3661assured: <fsssar> <bsssar> <fsscopsdu> <bsscopsdu>
<fsscopuu> <bsscopuu>
Each of these fields can be set to a "-" when the intention is to not
specify them in an SDP descriptor.
The <fsssar> and <bsssar> fields are 24-bit integers that
can be represented in decimal or in hex. The <fsscopsdu>,
<bsscopsdu>, <fsscopuu> and <bsscopuu> fields are 16-bit integers
that can be represented in decimal or in hex. The meaning and values
of these fields is as follows:
Field Meaning Values
<fsssar> Maximum SSSAR-SDU size 1- 65,568
forward direction
<bsssar> Maximum SSSAR-SDU size 1- 65,568
backward direction
<fsscopsdu> Maximum SSCOP-SDU size 1- 65,528
forward direction
<bsscopsdu> Maximum SSCOP-SDU size 1- 65,528
backward direction
<fsscopuu> Maximum SSCOP-UU field 1- 65,524
size, forward direction
<bsscopuu> Maximum SSCOP-UU field 1- 65,524
size, backward direction
The SSTED (Service-Specific Transmission Error Detection) sublayer
is above the SSSAR (Service-Specific Segmentation and Reassembly)
sublayer [12]. The SSADT (Service-Specific Assured Data Transfer)
sublayer is above the SSTED sublayer. Since the maximum size of
the SSTED-SDUs and SSADT-SDUs can be derived from the maximum
SSSAR-SDU size, they need not be specified separately.
The SSCOP protocol defined in [43] is used by the Assured Data
Transfer service defined in [12]. In the context of the ITU I.366.1
SSCS, it is possible to use the 'aal2sscs3661assured' attribute to limit
the maximum sizes of the SSCOP SDUs and UU (user-to-user) fields in
either direction. Note that it is necessary for the parameters on the
'aal2sscs3661assured' media attribute line to be consistent with each
other.
Rajesh Kumar, Mohamed Mostafa. 55
In certain applications (such as SIP-based applications), an SDP
descriptor might have an 'aal2sscs3661assured' media attribute line
with the forward and backward subparameters listed above. In other
applications (such as Megaco-based applications), the remote descriptor
can have the forward subparameters, and the local descriptor can have the
backward subparameters.
5.6.31 The 'aal5sscop' attribute
When present, the 'aal5sscop' attribute is used to indicate the
existence of an SSCOP [43] protocol layer over an AAL5 CPS
layer [21], and the parameters which pertain to this SSCOP layer.
SSCOP over AAL5 can also be selected via the aalApp attribute
defined below. The format of the 'aal5sscop' media attribute
line is as follows:
a=aal5sscop: <fsscopsdu> <bsscopsdu> <fsscopuu> <bsscopuu>
Each of these fields can be set to a "-" when the intention is to not
specify them in an SDP descriptor.
The representation, meaning and values of the <fsscopsdu>, <bsscopsdu>,
<fsscopuu> and <bsscopuu> fields are identical to those for the
'aal2sscs3661assured' media attribute line (Section 5.6.30). Note that it
is necessary for the parameters on the 'aal5sscop' media attribute
line to be consistent with each other.
In certain applications (such as SIP-based applications), an SDP
descriptor might have an 'aal5sscop' media attribute line
with the forward and backward subparameters listed above. In other
applications (such as Megaco-based applications), the remote descriptor
can have the forward subparameters, and the local descriptor can have the
backward subparameters.
5.6.32 The 'aal2sscs3662' attribute
When present, the 'aal2sscs3662' attribute is used to indicate When present, the 'aal2sscs3662' attribute is used to indicate
the options that pertain to the SSCS defined in ITU I.366.2 [13]. the options that pertain to the SSCS defined in ITU I.366.2 [13].
This SSCS can be selected via the aalApp attribute defined below This SSCS can be selected via the aalApp attribute defined below
or through the 'aal2sscs3662' attribute. The format of this or through the 'aal2sscs3662' attribute. The format of this
media attribute line is as follows: media attribute line is as follows:
a=aal2sscs3662: <sap> <circuitMode> <frameMode> <faxDemod> a=aal2sscs3662: <sap> <circuitMode> <frameMode> <faxDemod>
<cas> <dtmf> <mfall> <mfr1> <mfr2> <cas> <dtmf> <mfall> <mfr1> <mfr2>
<PCMencoding> <fmaxFrame> <bmaxFrame> <PCMencoding> <fmaxFrame> <bmaxFrame>
Each of these fields can be set to a "-" when the intention Each of these fields can be set to a "-" when the intention
is to not specify them in an SDP descriptor. Additionally, the values is to not specify them in an SDP descriptor. Additionally, the values
of these fields need to be consistent with each other. For instance, of these fields need to be consistent with each other. For instance,
<circuitMode> = on is inconsistent with <frameMode> = on. Inconsistencies <circuitMode> = on is inconsistent with <frameMode> = on. Inconsistencies
should be flagged as errors. should be flagged as errors.
Rajesh Kumar, Mohamed Mostafa. 56
The <sap> field can take on the following string values: "AUDIO" The <sap> field can take on the following string values: "AUDIO"
and "MULTIRATE". These correspond to the audio and multirate and "MULTIRATE". These correspond to the audio and multirate
Service Access Points (SAPs) defined in ITU I.366.2. Service Access Points (SAPs) defined in ITU I.366.2.
For the multirate SAP, the following parameters on the aal2sscs3662
attribute line do not apply: <faxDemod>,<cas>, <dtmf>, <mfall>,
<mfr1>, <mfr2> and <PCMencoding>. These are set to "-" for the
multirate SAP.
The <circuitMode> flag indicates whether the transport of circuit The <circuitMode> flag indicates whether the transport of circuit
mode data is enabled or disabled, corresponding to the string mode data is enabled or disabled, corresponding to the string
values of "on" and "off" respectively. values of "on" and "off" respectively. For the multirate SAP, it
cannot have a value of "off". For the audio SAP, it can be assigned
a value of "on", "off" or "-". Note that the <sbc> attribute, defined
elsewhere in this document, can be used to specify the number of
64 kbps subchannels bundled into a circuit mode data channel.
The <frameMode> flag indicates whether the transport of frame The <frameMode> flag indicates whether the transport of frame
mode data is enabled or disabled, corresponding to the string mode data is enabled or disabled, corresponding to the string
values of "on" and "off" respectively. values of "on" and "off" respectively.
The <faxDemod> flag indicates whether facsimile demodulation The <faxDemod> flag indicates whether facsimile demodulation
and remodulation are enabled or disabled, corresponding to the and remodulation are enabled or disabled, corresponding to the
string values of "on" and "off" respectively. string values of "on" and "off" respectively.
The <cas> flag indicates whether the transport of Channel The <cas> flag indicates whether the transport of Channel
Associated Signaling (CAS) bits in AAL2 type 3 packets is enabled Associated Signaling (CAS) bits in AAL2 type 3 packets is enabled
or disabled, corresponding to the string values of "on" and "off" or disabled, corresponding to the string values of "on" and "off"
Rajesh Kumar, Mohamed Mostafa. 43
respectively. respectively.
The <dtmf> flag indicates whether the transport of DTMF dialled The <dtmf> flag indicates whether the transport of DTMF dialled
digits in AAL2 type 3 packets is enabled or disabled, corresponding digits in AAL2 type 3 packets is enabled or disabled, corresponding
to the string values of "on" and "off" respectively. to the string values of "on" and "off" respectively.
The <mfall> flag indicates whether the transport of MF dialled The <mfall> flag indicates whether the transport of MF dialled
digits in AAL2 type 3 packets is enabled or disabled, corresponding digits in AAL2 type 3 packets is enabled or disabled, corresponding
to the string values of "on" and "off" respectively. This flag to the string values of "on" and "off" respectively. This flag
enables MF dialled digits in a generic manner, without specifying enables MF dialled digits in a generic manner, without specifying
skipping to change at line 2616 skipping to change at line 2962
or disabled, corresponding to the string values of "on" and "off" or disabled, corresponding to the string values of "on" and "off"
respectively. respectively.
The <mfr2> flag indicates whether the transport, in AAL2 type 3 The <mfr2> flag indicates whether the transport, in AAL2 type 3
packets, of MF dialled digits for signaling system R2 is enabled packets, of MF dialled digits for signaling system R2 is enabled
or disabled, corresponding to the string values of "on" and "off" or disabled, corresponding to the string values of "on" and "off"
respectively. respectively.
The <PCMencoding> field indicates whether PCM encoding, if used, The <PCMencoding> field indicates whether PCM encoding, if used,
is based on the A-law or the Mu-law. This can be used to qualify is based on the A-law or the Mu-law. This can be used to qualify
Rajesh Kumar, Mohamed Mostafa. 57
the 'generic PCM' codec stated in some of the AAL2 profiles. The the 'generic PCM' codec stated in some of the AAL2 profiles. The
<PCMencoding> field can take on the string values of "PCMA" <PCMencoding> field can take on the string values of "PCMA"
and "PCMU". and "PCMU".
The <fmaxFrame> and <bmaxFrame> fields are 16-bit integers that The <fmaxFrame> and <bmaxFrame> fields are 16-bit integers that
can be represented in decimal or in hex. The meaning and values of can be represented in decimal or in hex. The meaning and values of
the <fmaxFrame> and <bmaxFrame> fields are as follows: the <fmaxFrame> and <bmaxFrame> fields are as follows:
Field Meaning Values Field Meaning Values
<fmaxFrame> Maximum length of a 1- 65,535 <fmaxFrame> Maximum length of a 1- 65,535
frame mode data unit, frame mode data unit,
forward direction forward direction
<bmaxFrame> Maximum length of a 1- 65,535 <bmaxFrame> Maximum length of a 1- 65,535
frame mode data unit, frame mode data unit,
backward direction backward direction
In certain applications (such as SIP-based applications), an SDP In certain applications (such as SIP-based applications), an SDP
descriptor might have an 'aal2sscs3662' media attribute line descriptor might have an 'aal2sscs3662' media attribute line
with the <fmaxFrame> and <bmaxFrame> subparameters. In applications with the <fmaxFrame> and <bmaxFrame> subparameters. In other
(such as Megaco-based applications), the remote descriptor can have the applications (such as Megaco-based applications), the remote
<fmaxFrame> subparameter while the local descriptor can have the descriptor can have the <fmaxFrame> subparameter, and the local
<bmaxFrame> subparameter. descriptor can have the <bmaxFrame> subparameter.
5.6.31 The 'aalApp' attribute 5.6.33 The 'aalApp' attribute
When present, the 'aalApp' attribute is used to point to the When present, the 'aalApp' attribute is used to point to the
controlling standard for an application layer above the ATM adaptation controlling standard for an application layer above the ATM adaptation
layer. The format of the 'aalApp' media attribute line is as follows: layer. The format of the 'aalApp' media attribute line is as follows:
a=aalApp: <aalApp> a=aalApp: <aalApp>
The <aalApp> field can take on the string values listed The <aalApp> field can take on the string values listed
below, along with their meaning.
Rajesh Kumar, Mohamed Mostafa. 44
below, along with their meaning. Note that most applications which are
specified to run on AAL5 can also run on one or more of the AAL2
SSCS variants (TED and ADT) specified in I.366.1.
This list is not exhaustive. An "X-" prefix should be used with This list is not exhaustive. An "X-" prefix should be used with
non-standard values, not listed here, of the <aalApp> parameter. non-standard values, not listed here, of the <aalApp> parameter.
Rajesh Kumar, Mohamed Mostafa. 58
<aalApp> Meaning <aalApp> Meaning
"itu_h323c" Annex C of H.323 which specifies direct "itu_h323c" Annex C of H.323 which specifies direct
RTP on AAL5 [45]. RTP on AAL5 [45].
"af83" af-vtoa-0083.001, which specifies "af83" af-vtoa-0083.001, which specifies
variable size AAL5 PDUs with PCM voice variable size AAL5 PDUs with PCM voice
and a null SSCS [46]. and a null SSCS [46].
"assuredSSCOP" SSCOP as defined in ITU Q.2110 [43], "AAL5_SSCOP" SSCOP as defined in ITU Q.2110 [43]
assured operation. running over an AAL5 CPS [21].
No information is provided regarding
any layers above SSCOP such as Service
Specific Coordination Function (SSCF)
layers.
"nonassuredSSCOP" SSCOP as defined in ITU Q.2110 [43], "itu_i3661_unassured" SSCS with unassured transmission,
non-assured operation. per ITU I.366.1 [12].
"itu_i3661" SSCS per ITU I.366.1 [12]. "itu_i3661_assured" SSCS with assured transmission,
per ITU I.366.1 [12]. This uses SSCOP [43].
"itu_i3662" SSCS per ITU I.366.2 [13]. "itu_i3662" SSCS per ITU I.366.2 [13].
"itu_i3651" Frame relay SSCS per ITU I.365.1 [39]. "itu_i3651" Frame relay SSCS per ITU I.365.1 [39].
"itu_i3652" Service-specific coordination function, "itu_i3652" Service-specific coordination function,
as defined in ITU I.365.2, for Connection as defined in ITU I.365.2, for Connection
Oriented Network Service (SSCF-CONS) [40]. Oriented Network Service (SSCF-CONS) [40].
This uses SSCOP [43].
"itu_i3653" Service-specific coordination function, "itu_i3653" Service-specific coordination function,
as defined in ITU I.365.3, for Connection as defined in ITU I.365.3, for Connection
Oriented Transport Service (SSCF-COTS) [41]. Oriented Transport Service (SSCF-COTS) [41].
This uses SSCOP [43].
"FRF5" Use of the FRF.5 frame relay standard [53]. "itu_i3654" HDLC Service-specific coordination function,
as defined in ITU I.365.4 [42].
"FRF8" Use of the FRF.8 frame relay standard [54]. "FRF5" Use of the FRF.5 frame relay standard [53],
which references ITU I.365.1 [39].
"FRF8" Use of the FRF.8.1 frame relay standard [54].
This implies a null SSCS and the mapping of
the frame relay header into the ATM header.
"FRF11" Use of the FRF.11 frame relay standard [55]. "FRF11" Use of the FRF.11 frame relay standard [55].
"itu_h2221" Use of the ITU standard H.222.1 for audiovisual "itu_h2221" Use of the ITU standard H.222.1 for audiovisual
communication over AAL5 [51]. communication over AAL5 [51].
5.6.32 The 'lij' attribute Rajesh Kumar, Mohamed Mostafa. 59
5.6.34 The 'lij' attribute
When present, the 'lij' attribute is used to indicate When present, the 'lij' attribute is used to indicate
the presence of a connection that uses the Leaf-initiated-join the presence of a connection that uses the Leaf-initiated-join
capability described in UNI 4.0 [5], and to optionally describe capability described in UNI 4.0 [5], and to optionally describe
parameters associated with this capability. The format of the parameters associated with this capability. The format of the
'lij' media attribute line is as follows: 'lij' media attribute line is as follows:
a=lij: <sci><lsn> a=lij: <sci><lsn>
The <sci> (screening indication) is a 4-bit field expressed as a The <sci> (screening indication) is a 4-bit field expressed as a
decimal or hex integer. It is defined in the UNI 4.0 signaling decimal or hex integer. It is defined in the UNI 4.0 signaling
specification [5]. It is possible that the values of this field will specification [5]. It is possible that the values of this field will
be defined later by the ATMF and/or ITU. Currently, all values are be defined later by the ATMF and/or ITU. Currently, all values are
reserved with the exception of 0, which indicates a 'Network Join reserved with the exception of 0, which indicates a 'Network Join
Rajesh Kumar, Mohamed Mostafa. 45
without Root Notification'. without Root Notification'.
The <lsn> (leaf sequence number) is a 32-bit field expressed as a The <lsn> (leaf sequence number) is a 32-bit field expressed as a
decimal or hex integer. Per the UNI 4.0 signaling specification [5], it decimal or hex integer. Per the UNI 4.0 signaling specification [5], it
is used by a joining leaf to associate messages and responses during is used by a joining leaf to associate messages and responses during
LIJ (leaf initiated join) procedures. LIJ (leaf initiated join) procedures.
Each of these fields can be set to a "-" when the intention Each of these fields can be set to a "-" when the intention
is to not specify them in an SDP descriptor. is to not specify them in an SDP descriptor.
5.6.33 The 'anycast' attribute 5.6.35 The 'anycast' attribute
When present, the 'anycast' attribute line is used to indicate When present, the 'anycast' attribute line is used to indicate
the applicability of the anycast function described in UNI the applicability of the anycast function described in UNI
4.0 [5]. Optional parameters to qualify this function are 4.0 [5]. Optional parameters to qualify this function are
provided. The format of the 'anycast' attribute is: provided. The format of the 'anycast' attribute is:
a=anycast: <atmGroupAddress> <cdStd> <conScpTyp> <conScpSel> a=anycast: <atmGroupAddress> <cdStd> <conScpTyp> <conScpSel>
The <atmGroupAddress> is per Annex 5 of UNI 4.0 [5]. Within The <atmGroupAddress> is per Annex 5 of UNI 4.0 [5]. Within
an SDP descriptor, it can be represented in one of the formats an SDP descriptor, it can be represented in one of the formats
(NSAP, E.164, GWID/ALIAS) described elsewhere in this document. (NSAP, E.164, GWID/ALIAS) described elsewhere in this document.
The remaining subparameters mirror the connection scope selection The remaining subparameters mirror the connection scope selection
information element in UNI 4.0 [5]. Their meaning and representation information element in UNI 4.0 [5]. Their meaning and representation
is as shown below: is as shown below:
Rajesh Kumar, Mohamed Mostafa. 60
PARAMETER MEANING REPRESENTATION PARAMETER MEANING REPRESENTATION
<cdStd> Coding standard for the Decimal or hex <cdStd> Coding standard for the Decimal or hex
connection scope selection IE equivalent of connection scope selection IE equivalent of
Definition: UNI 4.0 [5] 2 bits Definition: UNI 4.0 [5] 2 bits
<conScpTyp> Type of connection scope Decimal or hex <conScpTyp> Type of connection scope Decimal or hex
Definition: UNI 4.0 [5] equivalent of Definition: UNI 4.0 [5] equivalent of
4 bits 4 bits
<conScpSel> Connection scope selection Decimal or hex <conScpSel> Connection scope selection Decimal or hex
Definition: UNI 4.0 [5] equivalent of Definition: UNI 4.0 [5] equivalent of
8 bits 8 bits
Currently, all values of <cdStd> and <conScpTyp> are reserved with Currently, all values of <cdStd> and <conScpTyp> are reserved with
the exception of <cdStd> = 3 (ATMF coding standard) and <conScpTyp> = 1 the exception of <cdStd> = 3 (ATMF coding standard) and <conScpTyp> = 1
(connection scope type of 'organizational'). (connection scope type of 'organizational').
Each of these fields can be set to a "-" when the intention Each of these fields can be set to a "-" when the intention
is to not specify them in an SDP descriptor. is to not specify them in an SDP descriptor.
5.6.34 The 'cache' attribute 5.6.36 The 'cache' attribute
This attribute is used to enable SVC caching. This attribute This attribute is used to enable SVC caching. This attribute
has the following format: has the following format:
a=cache:<cacheEnable><cacheTimer> a=cache:<cacheEnable><cacheTimer>
The <cacheEnable> flag indicates whether caching is enabled or The <cacheEnable> flag indicates whether caching is enabled or
not, corresponding to the string values of "on" and "off" not, corresponding to the string values of "on" and "off"
respectively. respectively.
The <cacheTimer> indicates the period of inactivity following which The <cacheTimer> indicates the period of inactivity following which
the SVC is to be released by sending an SVC release message into the SVC is to be released by sending an SVC release message into
Rajesh Kumar, Mohamed Mostafa. 46
the network. This is specified as the decimal or hex equivalent of the network. This is specified as the decimal or hex equivalent of
a 32-bit field, indicating the timeout in seconds. As usual, leading a 32-bit field, indicating the timeout in seconds. As usual, leading
zeros can be omitted. For instance, zeros can be omitted. For instance,
a=cache:on 7200 a=cache:on 7200
implies that the cached SVC is to be deleted if it is idle for 2 hours. implies that the cached SVC is to be deleted if it is idle for 2 hours.
The <cacheTimer> can be set to "-" if it is inapplicable or implied. The <cacheTimer> can be set to "-" if it is inapplicable or implied.
5.6.35 Specification of Higher-layer attributes 5.6.37 Specification of Higher-layer attributes
This conventions in this ATM SDP document are limited to the ATM and adaptation This conventions in this ATM SDP document are limited to the ATM and adaptation
layers. Parameters associated with layers higher than the ATM adaptation layers. Parameters associated with layers higher than the ATM adaptation
layer are addressed only if these are tightly coupled to the ATM or layer are addressed only if these are tightly coupled to the ATM or
adaptation layers. adaptation layers.
Rajesh Kumar, Mohamed Mostafa. 61
ATM signaling standards provide 'escape mechanisms' to ATM signaling standards provide 'escape mechanisms' to
represent, signal and negotiate higher-layer parameters. Examples represent, signal and negotiate higher-layer parameters. Examples
are the B-HLI and B-LLI IEs specified in ITU Q.2931 [15], and are the B-HLI and B-LLI IEs specified in ITU Q.2931 [15], and
the user-to-user information element described in ITU Q.2957 [48]. the user-to-user information element described in ITU Q.2957 [48].
SDP, as described in rfc2327, has a similar mechanism to SDP, as described in rfc2327, has a similar mechanism to
describe higher-layer parameters. This is the 'fmtp' or the describe higher-layer parameters. This is the 'fmtp' or the
format-specific parameters attribute. This attribute is expressed in format-specific parameters attribute. This attribute is expressed in
the following manner: the following manner:
a=fmtp:<format><format specific parameters> a=fmtp:<format><format specific parameters>
It is suggested that applications use this attribute, described in It is suggested that applications use this attribute, described in
detail in rfc2327 [1], to express higher-layer parameters. Conventions detail in rfc2327 [1], to express higher-layer parameters. Conventions
for the use of the 'fmtp' attribute to describe higher-layer information for the use of the 'fmtp' attribute to describe higher-layer information
are beyond the scope of the present document. However, it is recognized are beyond the scope of the present document. However, it is recognized
that in some applications it is necessary to describe higher-layer that in some applications it is necessary to describe higher-layer
information within the same SDP descriptor as the ATM and AAL information within the same SDP descriptor as the ATM and AAL
information. information.
5.6.36 Use of the second media-level part in H.323 Annex C applications 5.6.38 Use of the second media-level part in H.323 Annex C applications
Section 4 mentions that H.323 annex C applications have a second media level Section 4 mentions that H.323 annex C applications have a second media level
part for the ATM session description. This is used to convey information about part for the ATM session description. This is used to convey information about
the RTCP stream. Although the RTP stream is encapsulated in AAL5 with no the RTCP stream. Although the RTP stream is encapsulated in AAL5 with no
intervening IP layer, the RTCP stream is sent to an IP address and RTCP port. intervening IP layer, the RTCP stream is sent to an IP address and RTCP port.
This media level part has the following format: This media level part has the following format:
m= control <rtcpPortNum> H323c - m= control <rtcpPortNum> H323c -
c= IN IP4 <rtcpIPaddr> c= IN IP4 <rtcpIPaddr>
skipping to change at line 2836 skipping to change at line 3195
media-level part pertains to RTCP only. media-level part pertains to RTCP only.
The <rtcpPortNum> and <rtcpIPaddr> subparameters indicate the port number The <rtcpPortNum> and <rtcpIPaddr> subparameters indicate the port number
and IP address on which the media gateway is prepared to receive RTCP packets. and IP address on which the media gateway is prepared to receive RTCP packets.
Any of the subparameters on these lines can be set to "-" if they are known by Any of the subparameters on these lines can be set to "-" if they are known by
other means. other means.
The range and format of the <rtcpPortNum> and <rtcpIPaddr> subparameters is per The range and format of the <rtcpPortNum> and <rtcpIPaddr> subparameters is per
[1]. The <rtcpPortNum> is a decimal number between 1024 and 65535. It is an odd [1]. The <rtcpPortNum> is a decimal number between 1024 and 65535. It is an odd
Rajesh Kumar, Mohamed Mostafa. 47
number. If an even number in this range is specified, the next odd number is number. If an even number in this range is specified, the next odd number is
used. The <rtcpIPaddr> is expressed in the usual dotted decimal IP address used. The <rtcpIPaddr> is expressed in the usual dotted decimal IP address
representation, from 0.0.0.0 to 255.255.255.255. representation, from 0.0.0.0 to 255.255.255.255.
5.6.37 Chaining SDP descriptors Rajesh Kumar, Mohamed Mostafa. 62
5.6.39 Chaining SDP descriptors
The start of an SDP descriptor is marked by a 'v' line. In some The start of an SDP descriptor is marked by a 'v' line. In some
applications, consecutive SDP descriptions are alternative descriptions applications, consecutive SDP descriptions are alternative descriptions
of the same session. In others, these describe different layers of the of the same session. In others, these describe different layers of the
same connection (e.g. IP, ATM, frame relay). This is useful when these same connection (e.g. IP, ATM, frame relay). This is useful when these
connectivity at these layers are established at the same time e.g. an connectivity at these layers are established at the same time e.g. an
IP-based session over an ATM SVC. To distinguish between the IP-based session over an ATM SVC. To distinguish between the
alternation and concatenation of SDP descriptions, a 'chain' attribute alternation and concatenation of SDP descriptions, a 'chain' attribute
can be used in the case of concatenation. can be used in the case of concatenation.
skipping to change at line 2877 skipping to change at line 3235
a=chain:<chainPointer> a=chain:<chainPointer>
The <chainPointer> field can take on the following string values: The <chainPointer> field can take on the following string values:
"NEXT", "PREVIOUS" and "NULL". The value "NULL" is not equivalent to "NEXT", "PREVIOUS" and "NULL". The value "NULL" is not equivalent to
omitting the chain attribute from a description since it expressly omitting the chain attribute from a description since it expressly
precludes the possibility of chaining. If the 'chain' attribute is precludes the possibility of chaining. If the 'chain' attribute is
absent in an SDP description, chaining can still be realized by the absent in an SDP description, chaining can still be realized by the
presence of a chain media attribute line in the previous or next presence of a chain media attribute line in the previous or next
description. description.
5.6.38 Use of the eecid media attribute in call establishment procedures 5.6.40 Use of the eecid media attribute in call establishment procedures
This informative section supplements the definition of the eecid This informative section supplements the definition of the eecid
attribute (Section 5.6.2) by describing example procedures for its use. attribute (Section 5.6.2) by describing example procedures for its use.
These procedures assume a bearer-signaling mechanism for connection set-up These procedures assume a bearer-signaling mechanism for connection set-up
that is independent of service-level call control. These procedures are that is independent of service-level call control. These procedures are
independent of the media gateway control protocol (MGCP, Megaco, SIP etc.), independent of the media gateway control protocol (MGCP, Megaco, SIP etc.),
the protocol used between media gateway controllers (ITU Q.1901, SIP the protocol used between media gateway controllers (ITU Q.1901, SIP
etc.) and the protocol used for bearer connection set-up (Q.2931, UNI, PNNI, etc.) and the protocol used for bearer connection set-up (Q.2931, UNI, PNNI,
AINI, IISP, Q.2630.1 etc.). AINI, IISP, Q.2630.1 etc.).
Rajesh Kumar, Mohamed Mostafa. 48 Rajesh Kumar, Mohamed Mostafa. 63
Inter-MGC Inter-MGC
+---------+ Protocol +---------+ +---------+ Protocol +---------+
| MGC |------------------| MGC | | MGC |------------------| MGC |
+---------+ +---------+ +---------+ +---------+
| | | |
|Media Gateway |Media Gateway |Media Gateway |Media Gateway
|Control Protocol |Control Protocol |Control Protocol |Control Protocol
| | | |
+------------+ (ATM Network) +------------+ +------------+ (ATM Network) +------------+
|Originating |------------------|Terminating | |Originating |------------------|Terminating |
skipping to change at line 2939 skipping to change at line 3297
the appropriate mechanism (ISUP with Q.1901 extensions, SIP etc.). the appropriate mechanism (ISUP with Q.1901 extensions, SIP etc.).
It provides the TMGC with the NSAP address and the eecid provided It provides the TMGC with the NSAP address and the eecid provided
by the OMG. by the OMG.
(4) The TMGC sends the appropriate control message to the TMG. This (4) The TMGC sends the appropriate control message to the TMG. This
includes the session descriptor received from the OMG. This includes the session descriptor received from the OMG. This
descriptor contains the NSAP address of the OMG and the EECID descriptor contains the NSAP address of the OMG and the EECID
assigned by the OMG. Additionally, the TMGC instructs the TMG assigned by the OMG. Additionally, the TMGC instructs the TMG
to set up an SVC to the OMG. It also requests the TMG to notify to set up an SVC to the OMG. It also requests the TMG to notify
the TMGC when SVC set-up is complete. Depending on the control the TMGC when SVC set-up is complete. Depending on the control
Rajesh Kumar, Mohamed Mostafa. 64
protocol used, this can be done through a variety of means. protocol used, this can be done through a variety of means.
In the Megaco context, the request to set-up an SVC (not the In the Megaco context, the request to set-up an SVC (not the
notification request for the SVC set-up event) can be made through notification request for the SVC set-up event) can be made through
the following local descriptor: the following local descriptor:
Rajesh Kumar, Mohamed Mostafa. 49
v=0 v=0
o=- 2873397497 0 ATM - - o=- 2873397497 0 ATM - -
s=- s=-
c=ATM - - c=ATM - -
t=0 0 t=0 0
m=audio $ - - m=audio $ - -
a=bearerType:SVC on a=bearerType:SVC on
The 'bearerType' attribute indicates that an SVC is to be used and The 'bearerType' attribute indicates that an SVC is to be used and
that the <localInititiation> flag is on i.e. the SVC is to be set up that the <localInititiation> flag is on i.e. the SVC is to be set up
skipping to change at line 2991 skipping to change at line 3351
Note that, for this example, the "v=", "o=", "s=" and "t=" lines can be Note that, for this example, the "v=", "o=", "s=" and "t=" lines can be
omitted in the Megaco context. omitted in the Megaco context.
Example use of the Forward Call Model: Example use of the Forward Call Model:
(1) The originating media gateway controller (OMGC) initiates service-level (1) The originating media gateway controller (OMGC) initiates service-level
call establishment by sending the appropriate control message to the call establishment by sending the appropriate control message to the
originating media gateway (OMG). originating media gateway (OMG).
(2) The originating media gateway (OMG) provides its NSAP address (2) The originating media gateway (OMG) provides its NSAP address
Rajesh Kumar, Mohamed Mostafa. 65
to the OMGC, using the following SDP description: to the OMGC, using the following SDP description:
v=0 v=0
o=- 2873397496 0 ATM NSAP o=- 2873397496 0 ATM NSAP
47.0091.8100.0000.0060.3E64.FD01.0060.3E64.FD01.00 47.0091.8100.0000.0060.3E64.FD01.0060.3E64.FD01.00
s=- s=-
c=ATM NSAP c=ATM NSAP
47.0091.8100.0000.0060.3E64.FD01.0060.3E64.FD01.00 47.0091.8100.0000.0060.3E64.FD01.0060.3E64.FD01.00
t=0 0 t=0 0
m=audio $ AAL2/ITU 8 m=audio $ AAL2/ITU 8
The NSAP address information provided in this descriptor is not needed. The NSAP address information provided in this descriptor is not needed.
It can be omitted (by setting it to "- -"). It can be omitted (by setting it to "- -").
Rajesh Kumar, Mohamed Mostafa. 50
(3) The originating media gateway controller (OMGC) signals (3) The originating media gateway controller (OMGC) signals
the terminating media gateway controller (TMGC) through the terminating media gateway controller (TMGC) through
the appropriate mechanism (ISUP with Q.1901 extensions, SIP etc.). the appropriate mechanism (ISUP with Q.1901 extensions, SIP etc.).
Although this is not necessary, it can provide the TMGC with the Although this is not necessary, it can provide the TMGC with the
NSAP address provided by the OMG. NSAP address provided by the OMG.
(4) The TMGC sends the appropriate control message to the TMG. This (4) The TMGC sends the appropriate control message to the TMG. This
includes the session descriptor received from the OMG. This includes the session descriptor received from the OMG. This
descriptor contains the NSAP address of the OMG. descriptor contains the NSAP address of the OMG.
skipping to change at line 3044 skipping to change at line 3404
It provides the OMGC with the NSAP address and the eecid provided It provides the OMGC with the NSAP address and the eecid provided
by the TMG. by the TMG.
(7) The OMGC sends the appropriate control message to the OMG. This (7) The OMGC sends the appropriate control message to the OMG. This
includes the session descriptor received from the TMG. This includes the session descriptor received from the TMG. This
descriptor contains the NSAP address of the TMG and the EECID descriptor contains the NSAP address of the TMG and the EECID
assigned by the TMG. Additionally, the OMGC instructs the OMG assigned by the TMG. Additionally, the OMGC instructs the OMG
to set up an SVC to the TMG. It also requests the OMG to notify to set up an SVC to the TMG. It also requests the OMG to notify
the OMGC when SVC set-up is complete. Depending on the control the OMGC when SVC set-up is complete. Depending on the control
protocol used, this can be done through a variety of means. protocol used, this can be done through a variety of means.
Rajesh Kumar, Mohamed Mostafa. 66
In the Megaco context, the request to set-up an SVC (not the In the Megaco context, the request to set-up an SVC (not the
notification request for the SVC set-up event) can be made through notification request for the SVC set-up event) can be made through
the following local descriptor: the following local descriptor:
v=0 v=0
o=- 2873397874 0 ATM - - o=- 2873397874 0 ATM - -
s=- s=-
c=ATM - - c=ATM - -
t=0 0 t=0 0
m=audio $ - - m=audio $ - -
skipping to change at line 3069 skipping to change at line 3431
(8) The OMG acknowledges the control message from the OMGC. (8) The OMG acknowledges the control message from the OMGC.
(9) The OMG sends an SVC set-up message to the TMG. Within the GIT (9) The OMG sends an SVC set-up message to the TMG. Within the GIT
information element, it includes eecid (B3D58E32) received from information element, it includes eecid (B3D58E32) received from
the TMG. the TMG.
(10)The TMG uses the eecid to correlate the SVC set-up request with the (10)The TMG uses the eecid to correlate the SVC set-up request with the
service-level control message received before from the TMGC. service-level control message received before from the TMGC.
Rajesh Kumar, Mohamed Mostafa. 51
(11)The TMG returns an SVC connect message to the OMG. On receiving (11)The TMG returns an SVC connect message to the OMG. On receiving
this message, the OMG sends an event notification to the OMGC this message, the OMG sends an event notification to the OMGC
indicating successful SVC set-up. indicating successful SVC set-up.
Note that, for this example, the "v=", "o=", "s=" and "t=" lines can be Note that, for this example, the "v=", "o=", "s=" and "t=" lines can be
omitted in the Megaco context. omitted in the Megaco context.
Rajesh Kumar, Mohamed Mostafa. 67
6.0 List of Parameters with Representations 6.0 List of Parameters with Representations
This section provides a list of the parameters used in this document, This section provides a list of the parameters used in this document,
and the formats used to represent them in SDP descriptions. In general, a and the formats used to represent them in SDP descriptions. In general, a
"-" value can be used for any field that is not specified, is inapplicable "-" value can be used for any field that is not specified, is inapplicable
or is implied. or is implied.
PARAMETER MEANING REPRESENTATION PARAMETER MEANING REPRESENTATION
<username> User name Constant "-" <username> User name Constant "-"
skipping to change at line 3129 skipping to change at line 3491
representation representation
of <vcci> of <vcci>
<bcg> Bearer Connection Decimal or hex equivalent <bcg> Bearer Connection Decimal or hex equivalent
Group of 8 bits Group of 8 bits
<ex_bcg> Explicit "BCG-" prefixed to <bcg> <ex_bcg> Explicit "BCG-" prefixed to <bcg>
representation representation
of <bcg> of <bcg>
<portId> Port ID Hex number of up to 32 digits Rajesh Kumar, Mohamed Mostafa. 68
Rajesh Kumar, Mohamed Mostafa. 52 <portId> Port ID Hex number of up to 32 digits
<ex_portId> Explicit "PORT-" prefixed to <portId> <ex_portId> Explicit "PORT-" prefixed to <portId>
representation representation
of <portId> of <portId>
<vpi> Virtual Path Decimal or hex equivalent <vpi> Virtual Path Decimal or hex equivalent
Identifier of 8 or 12 bits Identifier of 8 or 12 bits
<ex_vpi> Explicit "VPI-" prefixed to <vpi> <ex_vpi> Explicit "VPI-" prefixed to <vpi>
representation representation
skipping to change at line 3178 skipping to change at line 3540
<transport> Transport Values listed in <transport> Transport Values listed in
Table 1. Table 1.
<profile> Profile Decimal integer 1-255 <profile> Profile Decimal integer 1-255
<eecid> End-to-end Up to 8 hex digits <eecid> End-to-end Up to 8 hex digits
Connection Connection
Identifier Identifier
Rajesh Kumar, Mohamed Mostafa. 69
<aalType> AAL type String values: <aalType> AAL type String values:
"AAL1","AAL1_SDT","AAL1_UDT", "AAL1","AAL1_SDT","AAL1_UDT",
"AAL2", "AAL3/4", "AAL2", "AAL3/4",
"AAL5", "USER_DEFINED_AAL" "AAL5", "USER_DEFINED_AAL"
<silenceSuppEnable> Silence suppression String values: <silenceSuppEnable> Silence suppression String values:
Enable "on", "off" Enable "on", "off"
<silenceTimer> Kick-in timer Decimal or hex representation <silenceTimer> Kick-in timer Decimal or hex representation
for silence of 16-bit field for silence of 16-bit field
suppression suppression
Rajesh Kumar, Mohamed Mostafa. 53
<suppPref> Preferred Silence String values: <suppPref> Preferred Silence String values:
Suppression Method "standard", "custom" Suppression Method "standard", "custom"
<sidUse> SID Use String values: <sidUse> SID Use String values:
Method "No SID", "Fixed Noise", Method "No SID", "Fixed Noise",
"Sampled Noise" "Sampled Noise"
<fxnslevel> Fixed Noise Decimal or hex representation <fxnslevel> Fixed Noise Decimal or hex representation
Level of a 7-bit field Level of a 7-bit field
<ecanEnable> Enable Echo String values: <ecanEnable> Enable Echo String values:
skipping to change at line 3226 skipping to change at line 3588
<uuiCodeRange> UUI code range Decimal integer 0-15 <uuiCodeRange> UUI code range Decimal integer 0-15
<encodingName> Encoding name String values: <encodingName> Encoding name String values:
"PCMG", "SIDG", "SID729", "PCMG", "SIDG", "SID729",
any value from column 2 any value from column 2
of Table 2 of Table 2
<packetLength> Packet length Decimal integer 0-45 <packetLength> Packet length Decimal integer 0-45
<packetTime> Packetization Decimal integer 1-255 <packetTime> Packetization Decimal integer 1-65,536
Interval Interval in microsec.
Rajesh Kumar, Mohamed Mostafa. 70
<fxIncl> Facsimile included String values: "on", "off" <fxIncl> Facsimile included String values: "on", "off"
<q7655scc> Contents of the Even number of hex
Q.765.5 Single digits (4-32)
Codec IE
<isupUsi> ISUP User Service Two hex digits
Information
<asc> ATM service String values: <asc> ATM service String values:
category defined "CBR", "nrt-VBR", "rt-VBR", category defined "CBR", "nrt-VBR", "rt-VBR",
by the ATMF "UBR", "ABR", "GFR" by the ATMF "UBR", "ABR", "GFR"
<atc> ATM transfer String values: <atc> ATM transfer String values:
capability "DBR","SBR","ABT/IT","ABT/DT", capability "DBR","SBR","ABT/IT","ABT/DT",
defined by the "ABR" defined by the "ABR"
ITU ITU
<subtype> <asc>/<atc> Decimal integer 1-10 <subtype> <asc>/<atc> Decimal integer 1-10
subtype subtype
<qosClass> QoS Class Decimal integer 0-5 <qosClass> QoS Class Decimal integer 0-5
<bcob> Broadband Bearer Decimal or hex representation <bcob> Broadband Bearer Decimal or hex representation
Class of 5-bit field Class of 5-bit field
<stc> Susceptibility Decimal equivalent of <stc> Susceptibility Decimal equivalent of
to clipping a 2-bit field to clipping a 2-bit field
Rajesh Kumar, Mohamed Mostafa. 54
<upcc> User plane Decimal equivalent of <upcc> User plane Decimal equivalent of
connection a 2-bit field connection a 2-bit field
configuration configuration
<cdvType> CDV type String values: <cdvType> CDV type String values:
"PP", "2P" "PP", "2P"
<acdv> Acceptable CDV Decimal equivalent <acdv> Acceptable CDV Decimal equivalent
of 24-bit field of 24-bit field
<ccdv> Cumulative CDV Decimal equivalent <ccdv> Cumulative CDV Decimal equivalent
of 24-bit field of 24-bit field
<actd> Acceptable CTD Decimal equivalent <actd> Acceptable CTD Decimal equivalent
of 16-bit field of 16-bit field
<cctd> Cumulative CTD Decimal equivalent <cctd> Cumulative CTD Decimal equivalent
of 16-bit field of 16-bit field
Rajesh Kumar, Mohamed Mostafa. 71
<aclr> Acceptable Decimal equivalent <aclr> Acceptable Decimal equivalent
Cell Loss Ratio of 8-bit field Cell Loss Ratio of 8-bit field
<clpLvl> CLP level String values: <clpLvl> CLP level String values:
"0", "0+1" "0", "0+1"
<pcr> Peak Decimal integer, 1-100,000 <pcr> Peak Decimal integer, 1-100,000
Cell Rate Cell Rate
<scr> Sustained Decimal integer, 1-100,000 <scr> Sustained Decimal integer, 1-100,000
skipping to change at line 3312 skipping to change at line 3683
<nrm> NRM Decimal/hex equivalent <nrm> NRM Decimal/hex equivalent
of 3 bit field of 3 bit field
<trm> TRM - ditto- <trm> TRM - ditto-
<cdf> CDF -ditto- <cdf> CDF -ditto-
<adtf> ADTF Decimal/Hex equivalent <adtf> ADTF Decimal/Hex equivalent
of 10 bit field of 10 bit field
Rajesh Kumar, Mohamed Mostafa. 55
<clkrec> Clock Recovery String values: <clkrec> Clock Recovery String values:
Method "NULL", "SRTS", Method "NULL", "SRTS",
"ADAPTIVE" "ADAPTIVE"
<fecEnable> Forward Error String values: <fecEnable> Forward Error String values:
Correction Enable "NULL", "LOSS_SENSITIVE" Correction Enable "NULL", "LOSS_SENSITIVE"
"DELAY_SENSITIVE" "DELAY_SENSITIVE"
<partialFill> Partial Fill Decimal integer 1-48 <partialFill> Partial Fill Decimal integer 1-48
or hex equivalent or hex equivalent
Rajesh Kumar, Mohamed Mostafa. 72
<bearerType> Bearer Type String Values: <bearerType> Bearer Type String Values:
"PVC", "SVC", "CID" "PVC", "SVC", "CID"
<localInititiation> Local Initiation String values: <localInititiation> Local Initiation String values:
"on", "off" "on", "off"
<structureEnable> Structure Present String values: <structureEnable> Structure Present String values:
"on", "off" "on", "off"
<blksz> Block Size Decimal or hexadecimal <blksz> Block Size Decimal or hexadecimal
skipping to change at line 3355 skipping to change at line 3726
or hex representation or hex representation
<cidCount> Number of Decimal integer 1-255 <cidCount> Number of Decimal integer 1-255
subcell channels or hex equivalent subcell channels or hex equivalent
<timerCU> Timer, combined use Integer decimal; range <timerCU> Timer, combined use Integer decimal; range
determined by application. determined by application.
Use decimal equivalent of Use decimal equivalent of
32 bits. 32 bits.
<adt> Assured Data String values: <simplifiedCPS> Simplified CPS [52] String values:
Transfer Enable "on", "off" "on", "off"
<ted> Transmission Error String values: <ted> Transmission Error String values:
Detection Enable "on", "off" Detection Enable "on", "off"
<fsssar> Maximum SSSAR-SDU Decimal or hex <fsssar> Maximum SSSAR-SDU Decimal 1- 65568
size, forward equivalent of 16-bit size, forward or hex equivalent
direction field direction
<bsssar> Maximum SSSAR-SDU Decimal or hex <bsssar> Maximum SSSAR-SDU Decimal 1- 65568
size, backward equivalent of 16-bit size, backward or hex equivalent
direction field direction
<fsscopsdu> Maximum SSCOP-SDU Decimal 1- 65528
size, forward or hex equivalent
direction
<bsscopsdu> Maximum SSCOP-SDU Decimal 1- 65528
size, backward or hex equivalent
direction
Rajesh Kumar, Mohamed Mostafa. 73
<fsscopuu> Maximum SSCOP-UU Decimal 1- 65524
field size, forward or hex equivalent
direction
<bsscopuu> Maximum SSCOP-UU Decimal 1- 65524
field size, backward or hex equivalent
direction
<sap> Service Access String values: <sap> Service Access String values:
Point "AUDIO", "MULTIRATE" Point "AUDIO", "MULTIRATE"
<circuitMode> Circuit Mode String values: <circuitMode> Circuit Mode String values:
Enable "on", "off" Enable "on", "off"
Rajesh Kumar, Mohamed Mostafa. 56
<frameMode> Frame Mode String values: <frameMode> Frame Mode String values:
Enable "on", "off" Enable "on", "off"
<faxDemod> Fax Demodulation String values: <faxDemod> Fax Demodulation String values:
Enable "on", "off" Enable "on", "off"
<cas> Enable CAS transport String values: <cas> Enable CAS transport String values:
via Type 3 packets "on", "off" via Type 3 packets "on", "off"
<dtmf> Enable DTMF transport String values: <dtmf> Enable DTMF transport String values:
skipping to change at line 3411 skipping to change at line 3798
"PCMA", "PCMU" "PCMA", "PCMU"
<fmaxFrame> Maximum length of a Decimal or hex <fmaxFrame> Maximum length of a Decimal or hex
frame mode data unit, equivalent of frame mode data unit, equivalent of
forward direction 16-bit field forward direction 16-bit field
<bmaxFrame> Maximum length of a -ditto- <bmaxFrame> Maximum length of a -ditto-
frame mode data unit, frame mode data unit,
backward direction backward direction
<aalApp> Application specification String values: Rajesh Kumar, Mohamed Mostafa. 74
"itu_h323c","af83",
"assuredSSCOP", <aalApp> Application String values:
"nonassuredSSCOP", specification "itu_h323c","af83",
"itu_i3661", "itu_i3662", "AAL5_SSCOP",
"itu_i3661_unassured",
"itu_i3661_assured",
"itu_i3662",
"itu_i3651", "itu_i3652", "itu_i3651", "itu_i3652",
"itu_i3653", "FRF11", "itu_i3653", "itu_i3654",
"FRF5", "FRF8", "FRF5", "FRF8","FRF11",
"itu_h2221" "itu_h2221"
<sci> Screening Indication Decimal or hex <sci> Screening Indication Decimal or hex
equivalent of 4 bits. equivalent of 4 bits.
<lsn> Leaf Sequence Number Decimal or hex <lsn> Leaf Sequence Number Decimal or hex
equivalent of 32 bits. equivalent of 32 bits.
<cdStd> Coding standard for the Decimal or hex <cdStd> Coding standard for the Decimal or hex
connection scope equivalent of connection scope equivalent of
selection IE 2 bits selection IE 2 bits
Definition: UNI 4.0 [5] Definition: UNI 4.0 [5]
<conScpTyp> Type of connection scope Decimal or hex <conScpTyp> Type of connection scope Decimal or hex
Definition: UNI 4.0 [5] equivalent of 4 bits Definition: UNI 4.0 [5] equivalent of 4 bits
<conScpSel> Connection scope selection Decimal or hex equivalent <conScpSel> Connection scope selection Decimal or hex equivalent
Definition: UNI 4.0 [5] of 8 bits Definition: UNI 4.0 [5] of 8 bits
Rajesh Kumar, Mohamed Mostafa. 57
<cacheEnable> Enable SVC caching String values: "on", "off" <cacheEnable> Enable SVC caching String values: "on", "off"
<cacheTimer> Timer for cached SVC Decimal or hex equivalent <cacheTimer> Timer for cached SVC Decimal or hex equivalent
deletion of 32-bit field deletion of 32-bit field
<rtcpPortNum> RTCP port number for Odd decimal in range 1,024 to <rtcpPortNum> RTCP port number for Odd decimal in range 1,024 to
H.323 Annex C applications 65,535. H.323 Annex C applications 65,535.
Preferred: Odd number in Preferred: Odd number in
the range 49,152 to 65,535 the range 49,152 to 65,535
<rtcpIPaddr> IP address for receipt Dotted decimal, 7-15 chars <rtcpIPaddr> IP address for receipt Dotted decimal, 7-15 chars
of RTCP packets of RTCP packets
<chainPointer> Chain pointer String values: "NEXT", <chainPointer> Chain pointer String values: "NEXT",
"PREVIOUS", "NULL" "PREVIOUS", "NULL"
Rajesh Kumar, Mohamed Mostafa. 75
7.0 Examples of ATM session descriptions using SDP 7.0 Examples of ATM session descriptions using SDP
An example of a complete AAL1 session description in SDP is: An example of a complete AAL1 session description in SDP is:
v=0 v=0
o=- A3C47F21456789F0 0 ATM NSAP o=- A3C47F21456789F0 0 ATM NSAP
47.0091.8100.0000.0060.3e64.fd01.0060.3e64.fd01.00 47.0091.8100.0000.0060.3e64.fd01.0060.3e64.fd01.00
s=- s=-
c=ATM NSAP c=ATM NSAP
47.0091.8100.0000.0060.3e64.fd01.0060.3e64.fd01.00 47.0091.8100.0000.0060.3e64.fd01.0060.3e64.fd01.00
skipping to change at line 3488 skipping to change at line 3879
t=0 0 t=0 0
m=audio $ AAL2/ITU 8 AAL2/custom 100 AAL2/ITU 1 m=audio $ AAL2/ITU 8 AAL2/custom 100 AAL2/ITU 1
a=eecid:B3E32 a=eecid:B3E32
The AAL2 session descriptor below is the same as the one above The AAL2 session descriptor below is the same as the one above
except that it states an explicit preference for a voice codec, a except that it states an explicit preference for a voice codec, a
voiceband data codec and a voiceband fax codec. Further, it defines voiceband data codec and a voiceband fax codec. Further, it defines
the profile AAL2/custom 100 rather than assume that the far-end is the profile AAL2/custom 100 rather than assume that the far-end is
cognizant of the elements of this profile. cognizant of the elements of this profile.
Rajesh Kumar, Mohamed Mostafa. 58
v=0 v=0
o=- A3C47F21456789F0 0 ATM NSAP o=- A3C47F21456789F0 0 ATM NSAP
47.0091.8100.0000.0060.3e64.fd01.0060.3e64.fd01.00 47.0091.8100.0000.0060.3e64.fd01.0060.3e64.fd01.00
s=- s=-
c=ATM NSAP c=ATM NSAP
47.0091.8100.0000.0060.3e64.fd01.0060.3e64.fd01.00 47.0091.8100.0000.0060.3e64.fd01.0060.3e64.fd01.00
t=0 0 t=0 0
m=audio $ AAL2/ITU 8 AAL2/custom 100 AAL2/ITU 1 m=audio $ AAL2/ITU 8 AAL2/custom 100 AAL2/ITU 1
a=eecid:B3E32 a=eecid:B3E32
a=profileDesc:AAL2/custom 100 0-7 PCMG 40 5 0-7 SIDG 1 a=profileDesc:AAL2/custom 100 0-7 PCMG 40 5000 0-7 SIDG 1
5 8-15 G726-32 40 10 8-15 SIDG 1 5 5000 8-15 G726-32 40 10000 8-15 SIDG 1 5000
a=vsel:G726-32 40 10 a=vsel:G726-32 40 10000
a=dsel:off PCMU - - a=dsel:off PCMU - -
a=fsel:G726-32 40 10 a=fsel:G726-32 40 10000
Rajesh Kumar, Mohamed Mostafa. 76
An example of an SDP session descriptor for an AAL5 switched virtual circuit An example of an SDP session descriptor for an AAL5 switched virtual circuit
for delivering MPEG-2 video: for delivering MPEG-2 video:
v=0 v=0
o=- A3C47F21456789F0 0 ATM NSAP o=- A3C47F21456789F0 0 ATM NSAP
47.0091.8100.0000.0060.3e64.fd01.0060.3e64.fd01.00 47.0091.8100.0000.0060.3e64.fd01.0060.3e64.fd01.00
s=- s=-
c=ATM NSAP 47.0091.8100.0000.0060.3e64.fd01.0060.3e64.fd01.00 c=ATM NSAP 47.0091.8100.0000.0060.3e64.fd01.0060.3e64.fd01.00
t=0 0 t=0 0
skipping to change at line 3537 skipping to change at line 3929
s=- s=-
c=ATM - - c=ATM - -
t=0 0 t=0 0
m=video PORT-$/VPI-0/VCI-$ AAL5/ITU 33 m=video PORT-$/VPI-0/VCI-$ AAL5/ITU 33
a=bearerType:PVC - a=bearerType:PVC -
a=atmFtrfcDesc:0+1 7816 - - - - - off - a=atmFtrfcDesc:0+1 7816 - - - - - off -
a=atmBtrfcDesc:0+1 0 - - - - - on - a=atmBtrfcDesc:0+1 0 - - - - - on -
a=fcpsSDUsize:20680 a=fcpsSDUsize:20680
a=aalApp:itu_h2221 a=aalApp:itu_h2221
8.0 Representation of data media 8.0 Security Considerations
The following encoding names in Table 2 can refer to data as well
as audio media: X-CCD and X-CCD-CAS in Table 2.
The following encoding names in Table 2 refer to data media:
X-FXDMOD-3 in Table 2.
In the AAL1 context, X-CCD and X-CCD-CAS can be represented as
"audio" codecs that are dynamically mapped into payload types. This
is done through the 'atmmap' attribute, as described earlier. For
example:
Rajesh Kumar, Mohamed Mostafa. 59
m=audio VCCI-27 AAL1/AVP 98
a=atmmap:98 X-CCD
implies that AAL1 VCCI=27 is used for n x 64 transmission.
Currently, AAL1 in unsuitable for transmitting demodulated facsimile
because it lacks the bearer plane mechanisms (equivalent to AAL2
type 3 messages) for transmitting control information.
In the AAL2 context, these "codecs" can be assigned profile types and
numbers. Even though it is not possible to construct
profile tables as described in ITU I.366.2 for these "codecs", it
is preferable to adopt the common AAL2 profile convention in their
case. An example AAL2 profile mapping for these could be as follows:
PROFILE TYPE PROFILE NUMBER "CODEC" (ONLY ONE)
"custom" 200 X-CCD
"custom" 201 X-FXDMOD-3
The profile does not identify the number of subchannels ('n' in nx64).
This is known by other means such as the 'sbc' media attribute line.
Currently, there is no definition of n x 64 trunking with CAS for AAL2.
For example, the media information line:
m=audio $ AAL2/custom 200
a=sbc:6
implies a 384 kbps n x 64 circuit using AAL2 adaptation.
In the case of fax demodulation and remodulation (ITU I.366.2),
parameters such as information type, image data size and control
type are negotiated in the 'bearer plane' via type 3 messages. There
is no need to define several encoding names for these control streams.
9.0 Security Considerations
9.1 Bearer Security 8.1 Bearer Security
At present, standard means of encrypting ATM and AAL2 bearers At present, standard means of encrypting ATM and AAL2 bearers
are not conventionalized in the same manner as means of encrypting RTP are not conventionalized in the same manner as means of encrypting RTP
payloads. Nor has the authentication of ATM or AAL2 bearer payloads. Nor has the authentication of ATM or AAL2 bearer
signaling. signaling.
The SDP encryption key line (k=) defined in rfc2327 can be used The SDP encryption key line (k=) defined in rfc2327 can be used
to represent the encryption key and the method of obtaining the to represent the encryption key and the method of obtaining the
key. In the ATM and AAL2 contexts, the term 'bearer' can include key. In the ATM and AAL2 contexts, the term 'bearer' can include
'bearer signaling' as well as 'bearer payloads'. 'bearer signaling' as well as 'bearer payloads'.
9.2 Security of the SDP description 8.2 Security of the SDP description
The SDP session descriptions might originate in untrusted areas The SDP session descriptions might originate in untrusted areas
such as equipment owned by end-subscribers or located at end-subscriber such as equipment owned by end-subscribers or located at end-subscriber
Rajesh Kumar, Mohamed Mostafa. 77
premises. SDP relies on the security mechanisms of the encapsulating premises. SDP relies on the security mechanisms of the encapsulating
protocol or layers below the encapsulating protocol. Examples of protocol or layers below the encapsulating protocol. Examples of
encapsulating protocols are the Session Initiation Protocol (SIP), encapsulating protocols are the Session Initiation Protocol (SIP),
MGCP and Multimedia Gateway Control Protocol (MEGACO). No additional MGCP and Multimedia Gateway Control Protocol (MEGACO). No additional
security mechanisms are needed. SIP, MGCP and MEGACO security mechanisms are needed. SIP, MGCP and MEGACO
can use IPSec authentication as described in RFC1826 [Ref. can use IPSec authentication as described in RFC1826 [Ref.
27]. IPSec encryption can be optionally used with authentication to 27]. IPSec encryption can be optionally used with authentication to
provide an additional, potentially more expensive level of security. provide an additional, potentially more expensive level of security.
IPSec security associations can be made between equipment located in IPSec security associations can be made between equipment located in
untrusted areas and equipment located in trusted areas through untrusted areas and equipment located in trusted areas through
Rajesh Kumar, Mohamed Mostafa. 60
configured shared secrets or the use of a certificate authority. configured shared secrets or the use of a certificate authority.
10. ATM SDP Grammar 9.0 ATM SDP Grammar
This appendix provides an Augmented BNF (ABNF) grammar for the ATM This appendix provides an Augmented BNF (ABNF) grammar for the ATM
conventions for SDP. ABNF is defined in rfc2234. This is not a complete ABNF conventions for SDP. ABNF is defined in rfc2234. This is not a complete ABNF
description of SDP. Readers are referred to [1] for an ABNF description description of SDP. Readers are referred to [1] for an ABNF description
of the SDP base line protocol, and to rfc2848, rfc2543, rfc2045 and rfc2326 of the SDP base line protocol, and to rfc2848, rfc2543, rfc2045 and rfc2326
for application-specific conventions for SDP use. for application-specific conventions for SDP use.
; Constant definitions ; Constant definitions
safe = alpha-numeric / "'" / "-" / "." / "/" / ":" / "?" / DQUOTE / "#" / safe = alpha-numeric / "'" / "-" / "." / "/" / ":" / "?" / DQUOTE / "#" /
skipping to change at line 3656 skipping to change at line 4000
decimal-uchar = DIGIT decimal-uchar = DIGIT
/ POS-DIGIT DIGIT / POS-DIGIT DIGIT
/ ("1" 2*(DIGIT)) / ("1" 2*(DIGIT))
/ ("2" ("0"/"1"/"2"/"3"/"4") DIGIT) / ("2" ("0"/"1"/"2"/"3"/"4") DIGIT)
/ ("2" "5" ("0"/"1"/"2"/"3"/"4"/"5")) / ("2" "5" ("0"/"1"/"2"/"3"/"4"/"5"))
generic-U8 = (hex-prefix hex-U8) / decimal-uchar generic-U8 = (hex-prefix hex-U8) / decimal-uchar
generic-U12 = (hex-prefix hex-U12) / 1*4 (DIGIT) generic-U12 = (hex-prefix hex-U12) / 1*4 (DIGIT)
generic-U16 = (hex-prefix hex-U16) / 1*5(DIGIT) generic-U16 = (hex-prefix hex-U16) / 1*5(DIGIT)
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generic-U24 = (hex-prefix hex-U24) / 1*8(DIGIT)
generic-U32 = (hex-prefix hex-U32) / 1*10(DIGIT) generic-U32 = (hex-prefix hex-U32) / 1*10(DIGIT)
hex-U8 = 1*2(HEXDIG) hex-U8 = 1*2(HEXDIG)
hex-U12 = 1*3(HEXDIG) hex-U12 = 1*3(HEXDIG)
hex-U16 = 1*4(HEXDIG) hex-U16 = 1*4(HEXDIG)
hex-U24 = 1*6(HEXDIG)
hex-U32 = 1*8(HEXDIG) hex-U32 = 1*8(HEXDIG)
generic-U8-or-null = generic-U8 / "-" generic-U8-or-null = generic-U8 / "-"
generic-U12-or-null = generic-U12 / "-" generic-U12-or-null = generic-U12 / "-"
generic-U16-or-null = generic-U16 / "-" generic-U16-or-null = generic-U16 / "-"
generic-U24-or-null = generic-U24 / "-"
generic-U32-or-null = generic-U32 / "-" generic-U32-or-null = generic-U32 / "-"
decimal-U8-or-null = decimal-uchar / "-" decimal-U8-or-null = decimal-uchar / "-"
decimal-U12-or-null = 1*4(DIGIT) / "-" decimal-U12-or-null = 1*4(DIGIT) / "-"
decimal-U16-or-null = 1*5(DIGIT) / "-" decimal-U16-or-null = 1*5(DIGIT) / "-"
decimal-U32-or-null = 1*10(DIGIT) / "-" decimal-U32-or-null = 1*10(DIGIT) / "-"
on-off-or-null = "on" / "off" / "-" on-off-or-null = "on" / "off" / "-"
; ABNF definition of SDP with ATM conventions ; ABNF definition of SDP with ATM conventions
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SDP-infoset = 1*(announcement)announcement = proto-version origin-field SDP-infoset = 1*(announcement)announcement = proto-version origin-field
session-name-field information-field uri-field email-fields phone-fields session-name-field information-field uri-field email-fields phone-fields
connection-field bandwidth-fields time-fields key-field attribute-fields media- connection-field bandwidth-fields time-fields key-field attribute-fields media-
descriptions descriptions
proto-version = ["v=" 1*4(DIGIT) EOL] ; use "v=0" for ATM SDP proto-version = ["v=" 1*4(DIGIT) EOL] ; use "v=0" for ATM SDP
origin-field = ["o=" username space sess-id space sess-version space origin-field = ["o=" username space sess-id space sess-version space
net-type-addr EOL] net-type-addr EOL]
skipping to change at line 3706 skipping to change at line 4054
; application level, not protocol syntax level ; application level, not protocol syntax level
addrtype-addr = atm-addrtype-addr / ip-addrtype-addr / tn-addrtype-addr addrtype-addr = atm-addrtype-addr / ip-addrtype-addr / tn-addrtype-addr
; ip-addrtype-addr per rfc2327 ; ip-addrtype-addr per rfc2327
; tn-addrtype-addr per rfc2848 ; tn-addrtype-addr per rfc2848
; ATM address definition ; ATM address definition
atm-addrtype-addr = atm-nsap-addr / atm-e164-addr / atm-alias-addr atm-addrtype-addr = atm-nsap-addr / atm-e164-addr / atm-alias-addr
Rajesh Kumar, Mohamed Mostafa. 79
atm-nsap-addr = ("NSAP" / "-" / "$") space (nsap-addr / "-" / "$") atm-nsap-addr = ("NSAP" / "-" / "$") space (nsap-addr / "-" / "$")
atm-e164-addr = ("E164" / "-" / "$") space (e164-addr / "-" / "$") atm-e164-addr = ("E164" / "-" / "$") space (e164-addr / "-" / "$")
atm-alias-addr = ("GWID" / "ALIAS" / "-" / "$") space (alias-addr / "-" / "$") atm-alias-addr = ("GWID" / "ALIAS" / "-" / "$") space (alias-addr / "-" / "$")
nsap-addr = 2(HEXDIG) "." 9(4(HEXDIG) ".") 2(HEXDIG) nsap-addr = 2(HEXDIG) "." 9(4(HEXDIG) ".") 2(HEXDIG)
e164-addr = 1*15 (DIGIT) e164-addr = 1*15 (DIGIT)
alias-addr = 1*32(alpha-numeric / "-" / "." / "_") alias-addr = 1*32(alpha-numeric / "-" / "." / "_")
session-name-field = ["s=" text EOL] ; for ATM use "s=-" session-name-field = ["s=" text EOL] ; for ATM use "s=-"
skipping to change at line 3735 skipping to change at line 4085
; connection-field required, not optional, in ATM ; connection-field required, not optional, in ATM
c-net-type-addr = nettype space c-addrtype-addr c-net-type-addr = nettype space c-addrtype-addr
c-addrtype-addr = atm-addrtype-addr / c-ip-addrtype-addr / tn-addrtype-addr c-addrtype-addr = atm-addrtype-addr / c-ip-addrtype-addr / tn-addrtype-addr
; atm-addrtype-addr defined above ; atm-addrtype-addr defined above
; c-ip-addrtype-addr per rfc2327 ; c-ip-addrtype-addr per rfc2327
; difference in address usage between 'o' and 'c' lines per rfc2327 ; difference in address usage between 'o' and 'c' lines per rfc2327
Rajesh Kumar, Mohamed Mostafa. 62
; tn-addrtype-addr per rfc2848 ; tn-addrtype-addr per rfc2848
bandwidth-fields = *("b=" bwtype ":" bandwidth EOL) bandwidth-fields = *("b=" bwtype ":" bandwidth EOL)
bwtype = 1*(alpha-numeric) bwtype = 1*(alpha-numeric)
bandwidth = 1*(DIGIT) bandwidth = 1*(DIGIT)
time-fields = *( "t=" start-time space stop-time *(EOL repeat-fields) EOL) time-fields = *( "t=" start-time space stop-time *(EOL repeat-fields) EOL)
[zone-adjustments EOL] [zone-adjustments EOL]
start-time = time / "0" start-time = time / "0"
stop-time = time / "0" ; always "0" in ATM stop-time = time / "0" ; always "0" in ATM
skipping to change at line 3757 skipping to change at line 4106
; repeat-fields and zone-adjustments per rfc2327, not used in ATM ; repeat-fields and zone-adjustments per rfc2327, not used in ATM
; Definition of optional key-field per rfc2327 ; Definition of optional key-field per rfc2327
; ;
attribute-fields = *("a=" attribute EOL) attribute-fields = *("a=" attribute EOL)
; SDP descriptors for ATM do not have session-level media attribute lines ; SDP descriptors for ATM do not have session-level media attribute lines
; If these are provided, they should be ignored. ; If these are provided, they should be ignored.
Rajesh Kumar, Mohamed Mostafa. 80
media-descriptions = *(media-description) media-descriptions = *(media-description)
media-description = media-field information-field *(connection-field) media-description = media-field information-field *(connection-field)
bandwidth-fields key-field attribute-fields bandwidth-fields key-field attribute-fields
; Definitions of information-field per rfc2327. This fields are omitted in ; Definitions of information-field per rfc2327. This fields are omitted in
; ATM SDP descriptions. If received, they are ignored in the ATM context ; ATM SDP descriptions. If received, they are ignored in the ATM context
; ;
; In ATM, the connection-field is used in media-description to indicate ; In ATM, the connection-field is used in media-description to indicate
; the IP address associated with the RTCP control protocol in H.323.C ; the IP address associated with the RTCP control protocol in H.323.C
; applications. In this case, the connection field is per the rfc2327 ; applications. In this case, the connection field is per the rfc2327
skipping to change at line 3792 skipping to change at line 4143
vcId = "$" / "-" / ex-vcci / (ex-vcci "/" ex-cid) / vcId = "$" / "-" / ex-vcci / (ex-vcci "/" ex-cid) /
(atm-type-addr-m "/" ex-vcci) / (atm-type-addr-m "/" ex-vcci) /
(atm-type-addr-m "/" ex-vcci "/" ex-cid) / (atm-type-addr-m "/" ex-vcci "/" ex-cid) /
(ex-bcg "/" ex-vcci) / (ex-bcg "/" ex-vcci "/" ex-cid) (ex-bcg "/" ex-vcci) / (ex-bcg "/" ex-vcci "/" ex-cid)
(ex-portid "/" ex-vpi "/" ex-vci) / (ex-portid "/" ex-vpi "/" ex-vci) /
(ex-portid "/" ex-vpi "/" ex-vci "/" ex-cid) / (ex-portid "/" ex-vpi "/" ex-vci "/" ex-cid) /
(ex-bcg "/" ex-vpi "/" ex-vci) / (ex-bcg "/" ex-vpi "/" ex-vci) /
(ex-bcg "/" ex-vpi "/" ex-vci "/" ex-cid) / (ex-bcg "/" ex-vpi "/" ex-vci "/" ex-cid) /
(ex-vpci "/" ex-vci) / (ex-vpci "/" ex-vci) /
(ex-vpci "/" ex-vci "/" ex-cid) / (ex-vpci "/" ex-vci "/" ex-cid) /
Rajesh Kumar, Mohamed Mostafa. 63
(atm-type-addr-m "/" ex-vpci "/" ex-vci) / (atm-type-addr-m "/" ex-vpci "/" ex-vci) /
(atm-type-addr-m "/" ex-vpci "/" ex-vci "/" ex-cid) (atm-type-addr-m "/" ex-vpci "/" ex-vci "/" ex-cid)
atm-type-addr-m = atm-nsap-addr-m / atm-e164-addr-m / atm-alias-addr-m atm-type-addr-m = atm-nsap-addr-m / atm-e164-addr-m / atm-alias-addr-m
atm-nsap-addr-m = ["NSAP-"] (nsap-addr / "$") atm-nsap-addr-m = ["NSAP-"] (nsap-addr / "$")
atm-e164-addr-m = ["E164-"] (e164-addr / "$") atm-e164-addr-m = ["E164-"] (e164-addr / "$")
atm-alias-addr-m = ["GWID-" / "ALIAS-"] (alias-addr / "$") atm-alias-addr-m = ["GWID-" / "ALIAS-"] (alias-addr / "$")
; The -m at the end indicates use in the media field ; The -m at the end indicates use in the media field
; Wildcarding rules different from ATM address on 'o' and 'c' lines ; Wildcarding rules different from ATM address on 'o' and 'c' lines
ex-vcci = "VCCI-" vcci ex-vcci = "VCCI-" vcci
ex-cid = "CID-" cid ex-cid = "CID-" cid
ex-bcg = "BCG-" bcg ex-bcg = "BCG-" bcg
ex-portid = "PORT-" portid ex-portid = "PORT-" portid
ex-vpi = "VPI-" vpi ex-vpi = "VPI-" vpi
ex-vci = "VCI-" vci ex-vci = "VCI-" vci
Rajesh Kumar, Mohamed Mostafa. 81
ex-vpci = "VPCI-" vpci ex-vpci = "VPCI-" vpci
vcci = generic-U16 vcci = generic-U16
cid = generic-U8 cid = generic-U8
bcg = generic-U8 bcg = generic-U8
portid = 1*32 (HEXDIG) portid = 1*32 (HEXDIG)
vpi = generic-U12 vpi = generic-U12
vci = generic-U16 vci = generic-U16
vpci = generic-U16 vpci = generic-U16
skipping to change at line 3854 skipping to change at line 4206
rtp-transport = "RTP" "/" rtp-transport-list rtp-transport = "RTP" "/" rtp-transport-list
rtp-transport-list = "AVP" rtp-transport-list = "AVP"
aal1-fmt-list = (payload-type *(space payload-type)) / "-" aal1-fmt-list = (payload-type *(space payload-type)) / "-"
payload-type = decimal-uchar payload-type = decimal-uchar
aal5-fmt-list = aal1-fmt-list aal5-fmt-list = aal1-fmt-list
rtp-fmt-list = aal1-fmt-list rtp-fmt-list = aal1-fmt-list
aal2-fmt-list = (profile *(space profile)) / "-" aal2-fmt-list = (profile *(space profile)) / "-"
profile = decimal-uchar profile = decimal-uchar
Rajesh Kumar, Mohamed Mostafa. 64
attribute-fields = *("a=" attribute EOL) attribute-fields = *("a=" attribute EOL)
attribute = known-attribute / (generic-att-field ":" att-value) / attribute = known-attribute / (generic-att-field ":" att-value) /
generic-att-field generic-att-field
generic-att-field = 1*(alpha-numeric) generic-att-field = 1*(alpha-numeric)
att-value = byte-string att-value = byte-string
known-attribute = atm-attribute / PIMT-attribute / rfc2327-attribute known-attribute = atm-attribute / PINT-attribute / rfc2327-attribute
Rajesh Kumar, Mohamed Mostafa. 82
; PINT-attribute as defined in rfc2848 ; PINT-attribute as defined in rfc2848
; rfc2327 attribute as defined in that rfc ; rfc2327 attribute as defined in that rfc
atm-attribute = atm-attribute =
"atmmap" ":" payload-type space encoding-name / "atmmap" ":" payload-type space encoding-name /
"eecid" ":" eecid / "eecid" ":" eecid /
"aalType" ":" aal-type / "aalType" ":" aal-type /
"silenceSupp" ":" silenceSuppEnable space silenceTimer space suppPref "silenceSupp" ":" silenceSuppEnable space silenceTimer space suppPref
space sidUse space fxnslevel / space sidUse space fxnslevel /
"ecanf" ":" ecanEnable space ecanType / "ecanf" ":" ecanEnable space ecanType /
skipping to change at line 3885 skipping to change at line 4237
"profileDesc" ":" aal2-transport space profile space "profileDesc" ":" aal2-transport space profile space
1*(profile-row) / 1*(profile-row) /
"vsel" ":" 1*(encoding-name space packet-length space "vsel" ":" 1*(encoding-name space packet-length space
packet-time space) / packet-time space) /
"dsel" ":" fxIncl space "dsel" ":" fxIncl space
1*(encoding-name space packet-length space 1*(encoding-name space packet-length space
packet-time space) / packet-time space) /
"fsel" ":" 1*(encoding-name space packet-length space "fsel" ":" 1*(encoding-name space packet-length space
packet-time space) / packet-time space) /
"capability" ":" (asc / atc / 1*(alpha-numeric)) space capab-subtype / "codecconfig" ":" q7655scc /
"isup_usi" ":" isupUsi /
"capability" ":" (asc / atc / 1*(alpha-numeric)) space subtype /
"qosclass" ":" qosclass / "qosclass" ":" qosclass /
"bcob" ":" bcob / "bcob" ":" bcob /
"stc" ":" stc / "stc" ":" stc /
"upcc" ":" upcc / "upcc" ":" upcc /
"atmQOSfparms" ":" cdvType space acdv space ccdv space actd space cctd "atmQOSfparms" ":" cdvType space acdv space ccdv space actd space cctd
space aclr / space aclr /
"atmQOSbparms" ":" cdvType space acdv space ccdv space actd space cctd "atmQOSbparms" ":" cdvType space acdv space ccdv space actd space cctd
space aclr / space aclr /
"aal2QOSfparms" ":" byte-string /
"aal2QOSbparms" ":" byte-string /
"atmFtrfcDesc" ":" clpLvl space pcr space scr space mbs space cdvt space "atmFtrfcDesc" ":" clpLvl space pcr space scr space mbs space cdvt space
mcr space mfs space fd space te / mcr space mfs space fd space te /
"atmBtrfcDesc" ":" clpLvl space pcr space scr space mbs space cdvt space "atmBtrfcDesc" ":" clpLvl space pcr space scr space mbs space cdvt space
mcr space mfs space fd space te / mcr space mfs space fd space te /
"aal2FtrfcDesc" ":" byte-string /
"aal2BtrfcDesc" ":" byte-string /
"abrFparms" ":" nrm space trm space cdf space adtf / "abrFparms" ":" nrm space trm space cdf space adtf /
"abrBparms" ":" nrm space trm space cdf space adtf / "abrBparms" ":" nrm space trm space cdf space adtf /
"clkrec" ":" clkrec / "clkrec" ":" clkrec /
"fec" ":" fecEnable / "fec" ":" fecEnable /
"prtfl" ":" partialFill / "prtfl" ":" partialFill /
"bearertype" ":" bearerType space localInitiation / "bearertype" ":" bearerType space localInitiation /
"structure" ":" structureEnable space blksz / "structure" ":" structureEnable space blksz /
"sbc" ":" sbc / "sbc" ":" sbc /
"fcpsSDUsize" ":" cpcs / "fcpsSDUsize" ":" cpcs /
"bcpsSDUsize" ":" cpcs / "bcpsSDUsize" ":" cpcs /
"aal2CPS" ":" cidCount space timerCU / "aal2CPS" ":" cidCount space timerCU space simplifiedCPS /
"aal2sscs3661" ":" adt space ted space fsssar space bsssar / "aal2sscs3661unassured" ":" ted space fsssar space bsssar /
"aal2sscs3661assured" ":" fsssar space bsssar space fsscopsdu
space bsscopsdu space fsscopuu space bsscopuu /
Rajesh Kumar, Mohamed Mostafa. 83
"aal5sscop" ":" fsscopsdu space bsscopsdu space fsscopuu
space bsscopuu /
"aal2sscs3662" ":" sap space circuitMode space frameMode space faxDemod "aal2sscs3662" ":" sap space circuitMode space frameMode space faxDemod
space cas space dtmf space mfall space mfr1 space cas space dtmf space mfall space mfr1
Rajesh Kumar, Mohamed Mostafa. 65
space mfr2 space PCMencoding space fmaxFrame space bmaxFrame / space mfr2 space PCMencoding space fmaxFrame space bmaxFrame /
"aalApp" ":" aalApp / "aalApp" ":" aalApp /
"lij" ":" sci space lsn / "lij" ":" sci space lsn /
"anycast" ":" atmGroupAddress space cdStd space "anycast" ":" atmGroupAddress space cdStd space
conScpTyp space conScpSel / conScpTyp space conScpSel /
"cache" ":" cacheEnable space cacheTimer "cache" ":" cacheEnable space cacheTimer
"chain" ":" chainPointer "chain" ":" chainPointer
eec-id = hex-U32 eecid = 8 (HEXDIG)
aalType = "AAL1" / "AAL2" / "AAL3/4" / "AAL5" / "USER_DEFINED_AAL" aalType = "AAL1" / "AAL2" / "AAL3/4" / "AAL5" / "USER_DEFINED_AAL"
silenceSuppEnable = on-off-or-null silenceSuppEnable = on-off-or-null
silenceTimer = generic-U16-or-null silenceTimer = generic-U16-or-null
suppPref = "standard" / "custom" / "-" suppPref = "standard" / "custom" / "-"
sidUse = "No SID" / "Fixed Noise" / "Sampled Noise" / "-" sidUse = "No SID" / "Fixed Noise" / "Sampled Noise" / "-"
fxnslevel = generic-U8-or-null fxnslevel = generic-U8-or-null
ecanEnable = on-off-or-null ecanEnable = on-off-or-null
ecanType = "G165" / "G168" / "-" ecanType = "G165" / "G168" / "-"
gcEnable = on-off-or-null gcEnable = on-off-or-null
gcLvl = generic-U16-or-null gcLvl = generic-U16-or-null
skipping to change at line 3948 skipping to change at line 4302
profile-row = uuiCodeRange space encoding-name space packet-length profile-row = uuiCodeRange space encoding-name space packet-length
space packet-time space space packet-time space
uuiCodeRange = decimal-uchar "-" decimal-uchar / "-" uuiCodeRange = decimal-uchar "-" decimal-uchar / "-"
encoding-name = "-" / encoding-name = "-" /
"PCMG" / "SIDG" / "SID729" / "PCMG" / "SIDG" / "SID729" /
"PCMU" / "G726-32" / "G723" / "PCMA" / "G722" / "G728" / "PCMU" / "G726-32" / "G723" / "PCMA" / "G722" / "G728" /
"G729" / "X-G729a" / "X-G729b" / "X-G729ab" / "X-G726-16" / "G729" / "X-G729a" / "X-G729b" / "X-G729ab" / "X-G726-16" /
"X-G726-24" / "X-G726-40" / "X-G7231-H" / "X-G7231-L" / "X-G726-24" / "X-G726-40" / "X-G7231-H" / "X-G7231-L" /
"X-G7231a-H" / "X-G7231a-L" / "X-G727-16" / "X-G727-24" / "X-G7231a-H" / "X-G7231a-L" / "X-G727-16" / "X-G727-24" /
"X-G727-32" / "X-G727-32" /
"X-CCD" / "X-CCD-CAS" / "GSM" / "X-GSM-HR" / "X-GSM-EFR" / "X-CCD" / "X-CCD-CAS" / "GSM" / "GSM-HR" / "GSM-EFR" /
"X-GSM-EHR" / "X-FXDMOD-3" / "1016" / "DVI4" / "L16" / "LPC" / "GSM-EHR" / "X-FXDMOD-3" / "1016" / "DVI4" / "L16" / "LPC" /
"MPA" / "QCELP" / "H263" / "H263-1998" / "MPA" / "QCELP" / "H263" / "H263-1998" /
"JPEG" / "H261" / "MPV" / "MP2T" / "nv" / "RED" / "X-RED" / "JPEG" / "H261" / "MPV" / "MP2T" / "nv" / "RED" /
"CelB" / "L8" / "VDVI" / "MP1S" / "MP2P" "CelB" / "L8" / "VDVI" / "MP1S" / "MP2P" / "BT656" /
"FR-AMR" / "HR-AMR" / "HR-UMTS"
packet-length = decimal-U8-or-null packet-length = decimal-U8-or-null
packet-time = decimal-U8-or-null packet-time = decimal-U16-or-null
fxIncl = on-off-or-null fxIncl = on-off-or-null
q7655scc = 4*32 (HEXDIG)
isupUsi = 2 (HEXDIG)
asc = "CBR" / "nrt-VBR" / "rt-VBR" / "UBR" / "ABR" / "GFR" asc = "CBR" / "nrt-VBR" / "rt-VBR" / "UBR" / "ABR" / "GFR"
atc = "DBR" / "SBR" / "ABT/IT" / "ABT/DT" / "ABR" atc = "DBR" / "SBR" / "ABT/IT" / "ABT/DT" / "ABR"
capab-subtype = decimal-U8-or-null subtype = decimal-U8-or-null
qosclass = decimal-U8-or-null qosclass = decimal-U8-or-null
bcob = generic-U8 bcob = generic-U8
stc = decimal-uchar stc = decimal-uchar
Rajesh Kumar, Mohamed Mostafa. 84
upcc = decimal-uchar upcc = decimal-uchar
cdvType = "PP" / "2P" / "-" cdvType = "PP" / "2P" / "-"
acdv = decimal-U32-or-null acdv = decimal-U32-or-null
ccdv = decimal-U32-or-null ccdv = decimal-U32-or-null
actd = decimal-U16-or-null actd = decimal-U16-or-null
cctd = decimal-U16-or-null cctd = decimal-U16-or-null
aclr = decimal-U8-or-null aclr = decimal-U8-or-null
clpLvl = "0" / "0+1" / "-" clpLvl = "0" / "0+1" / "-"
pcr = decimal-U32-or-null pcr = decimal-U32-or-null
scr = decimal-U32-or-null scr = decimal-U32-or-null
mbs = decimal-U16-or-null mbs = decimal-U16-or-null
cdvt = decimal-U32-or-null cdvt = decimal-U32-or-null
mcr = decimal-U32-or-null mcr = decimal-U32-or-null
mfs = decimal-U16-or-null mfs = decimal-U16-or-null
fd = on-off-or-null fd = on-off-or-null
te = on-off-or-null te = on-off-or-null
Rajesh Kumar, Mohamed Mostafa. 66
nrm = generic-U8-or-null nrm = generic-U8-or-null
trm = generic-U8-or-null trm = generic-U8-or-null
cdf = generic-U8-or-null cdf = generic-U8-or-null
adtf = generic-U16-or-null adtf = generic-U16-or-null
clkrec = "NULL" / "SRTS" / "ADAPTIVE" clkrec = "NULL" / "SRTS" / "ADAPTIVE"
fecEnable = "NULL" / "LOSS_SENSITIVE" / "DELAY_SENSITIVE" fecEnable = "NULL" / "LOSS_SENSITIVE" / "DELAY_SENSITIVE"
partialFill = generic-U8 partialFill = generic-U8
bearerType = "PVC" / "SVC" / "CID" bearerType = "PVC" / "SVC" / "CID"
localInitiation = on-off-or-null localInitiation = on-off-or-null
structureEnable = on-off-or-null structureEnable = on-off-or-null
blksz = generic-U16-or-null blksz = generic-U16-or-null
sbc = generic-U8 sbc = generic-U8
cpcs = generic-U16 cpcs = generic-U16
cidCount = generic-U8-or-null cidCount = generic-U8-or-null
timerCU = decimal-U32-or-null timerCU = decimal-U32-or-null
adt = on-off-or-null simplifiedCPS = on-off-or-null
ted = on-off-or-null ted = on-off-or-null
fsssar = generic-U16-or-null fsssar = generic-U24-or-null
bsssar = generic-U16-or-null bsssar = generic-U24-or-null
fsscopsdu = generic-U16-or-null
bsscopsdu = generic-U16-or-null
fsscopuu = generic-U16-or-null
bsscopuu = generic-U16-or-null
sap = "AUDIO" / "MULTIRATE" / "-" sap = "AUDIO" / "MULTIRATE" / "-"
circuitMode = on-off-or-null circuitMode = on-off-or-null
frameMode = on-off-or-null frameMode = on-off-or-null
faxDemod = on-off-or-null faxDemod = on-off-or-null
cas = on-off-or-null cas = on-off-or-null
dtmf = on-off-or-null dtmf = on-off-or-null
mfall = on-off-or-null mfall = on-off-or-null
mfr1 = on-off-or-null mfr1 = on-off-or-null
mfr2 = on-off-or-null mfr2 = on-off-or-null
PCMencoding = "PCMA" / "PCMU" / "-" PCMencoding = "PCMA" / "PCMU" / "-"
fmaxframe = generic-U16-or-null fmaxframe = generic-U16-or-null
bmaxframe = generic-U16-or-null bmaxframe = generic-U16-or-null
aalApp =
AAL5app = "-" / Rajesh Kumar, Mohamed Mostafa. 85
"itu_h323c" / "af83" / "assuredSSCOP" / "nonassuredSSCOP" /
"itu_i3661"/ "itu_i3662"/ "itu_i3651" / aalApp = "-" /
"itu_i3652" / "itu_i3653" / "FRF11" / "FRF5" / "FRF8" / "itu_h2221" "itu_h323c" / "af83" / "AAL5_SSCOP" / "itu_i3661_unassured" /
"itu_ i3661_assured"/ "itu_i3662"/ "itu_i3651" /
"itu_i3652" / "itu_i3653" / "itu_i3654" / "FRF11" / "FRF5" / "FRF8" /
"itu_h2221"
sci = generic-U8-or-null sci = generic-U8-or-null
lsn = generic-U32-or-null lsn = generic-U32-or-null
atmGroupAddress = atm-type-addr atmGroupAddress = atm-type-addr
cdStd = generic-U8-or-null cdStd = generic-U8-or-null
conScpTyp = generic-U8-or-null conScpTyp = generic-U8-or-null
conScpSel = generic-U8-or-null conScpSel = generic-U8-or-null
cacheEnable = on-off-or-null cacheEnable = on-off-or-null
cacheTimer = generic-U32-or-null cacheTimer = generic-U32-or-null
chainPointer = "NEXT" / "PREVIOUS" / "NULL" chainPointer = "NEXT" / "PREVIOUS" / "NULL"
skipping to change at line 4041 skipping to change at line 4405
[2] IETF RFC 1889, 'RTP: A Transport Protocol for Real-Time [2] IETF RFC 1889, 'RTP: A Transport Protocol for Real-Time
Applications', Jan. 1996. Applications', Jan. 1996.
RFC1889 will be obsoleted, in a substantially backwards compatible RFC1889 will be obsoleted, in a substantially backwards compatible
manner, by the RFC that evolves out of draft-ietf-avt-rtp-new-08.txt. manner, by the RFC that evolves out of draft-ietf-avt-rtp-new-08.txt.
[3] IETF RFC 1890, 'RTP Profile for Audio and Video Conferences [3] IETF RFC 1890, 'RTP Profile for Audio and Video Conferences
with Minimal Control', Jan. 1996. with Minimal Control', Jan. 1996.
Rajesh Kumar, Mohamed Mostafa. 67
RFC1890 will be obsoleted, in a fully backwards compatible manner, RFC1890 will be obsoleted, in a fully backwards compatible manner,
by the RFC that evolves out of draft-ietf-avt-profile-new-09.txt. by the RFC that evolves out of draft-ietf-avt-profile-new-09.txt.
[4] ATMF UNI 3.1 Specification, af-uni-0010.002. Of special [4] ATMF UNI 3.1 Specification, af-uni-0010.002. Of special
interest for this document is Section 5.4.5.5, ATM Adaptation interest for this document is Section 5.4.5.5, ATM Adaptation
Layer Parameters. Layer Parameters.
[5] ATMF UNI 4.0 Signaling Specification, af-sig-0061.000. [5] ATMF UNI 4.0 Signaling Specification, af-sig-0061.000.
[6] ATMF Traffic Management Specification, Version 4.1, af-tm- [6] ATMF Traffic Management Specification, Version 4.1, af-tm-
skipping to change at line 4064 skipping to change at line 4427
[7] ATMF Circuit Emulation Service (CES) Interoperability [7] ATMF Circuit Emulation Service (CES) Interoperability
Specification, version 2.0, af-vtoa-0078.000, Jan. 97. Specification, version 2.0, af-vtoa-0078.000, Jan. 97.
[8] ATMF Voice and Telephony over ATM - ATM Trunking using AAL1 for [8] ATMF Voice and Telephony over ATM - ATM Trunking using AAL1 for
Narrowband Services, version 1.0, af-vtoa-0089.000, July 1997. Narrowband Services, version 1.0, af-vtoa-0089.000, July 1997.
[9] ATMF Specifications of (DBCES) Dynamic Bandwidth Utilization - [9] ATMF Specifications of (DBCES) Dynamic Bandwidth Utilization -
in 64kbps Timeslot Trunking over ATM - using CES, af-vtoa- in 64kbps Timeslot Trunking over ATM - using CES, af-vtoa-
0085.000, July 1997. 0085.000, July 1997.
Rajesh Kumar, Mohamed Mostafa. 86
[10] ITU-T I.363.1, B-ISDN ATM Adaptation Layer Specification: Type [10] ITU-T I.363.1, B-ISDN ATM Adaptation Layer Specification: Type
1 AAL, August 1996. 1 AAL, August 1996.
[11] ITU-T I.363.2, B-ISDN ATM Adaptation Layer Specification: Type [11] ITU-T I.363.2, B-ISDN ATM Adaptation Layer Specification: Type
2 AAL, Sept. 1997. 2 AAL, Sept. 1997.
[12] ITU-T I.366.1, Segmentation and Reassembly Service Specific [12] ITU-T I.366.1, Segmentation and Reassembly Service Specific
Convergence Sublayer for AAL Type 2, June 1998. Convergence Sublayer for AAL Type 2, June 1998.
[13] ITU-T I.366.2, AAL Type 2 Reassembly Service Specific [13] ITU-T I.366.2, AAL Type 2 Reassembly Service Specific
skipping to change at line 4103 skipping to change at line 4468
[20] rfc2474, Definition of the Differentiated Services Field (DS [20] rfc2474, Definition of the Differentiated Services Field (DS
Field) in the IPv4 and IPv6 Headers. K. Nichols, S. Blake, F. Field) in the IPv4 and IPv6 Headers. K. Nichols, S. Blake, F.
Baker, D. Black. December 1998. Baker, D. Black. December 1998.
[21] ITU-T I.363.5, B-ISDN ATM Adaptation Layer Specification: Type [21] ITU-T I.363.5, B-ISDN ATM Adaptation Layer Specification: Type
5 AAL, Aug. 1996. 5 AAL, Aug. 1996.
[22] ATMF PNNI 1.0, af-pnni-0055.000, March 1996. [22] ATMF PNNI 1.0, af-pnni-0055.000, March 1996.
Rajesh Kumar, Mohamed Mostafa. 68
[23] ietf-avt-rtp-new-05.txt, Oct. 21, 1999, RTP: A Transport [23] ietf-avt-rtp-new-05.txt, Oct. 21, 1999, RTP: A Transport
Protocol for Real-Time Applications. Protocol for Real-Time Applications.
[24] ietf-avt-profile-new-07.txt, Oct. 21, 1999, RTP Profile for [24] ietf-avt-profile-new-07.txt, Oct. 21, 1999, RTP Profile for
Audio and Video Conferences with Minimal Control. Audio and Video Conferences with Minimal Control.
[25] Media Gateway Control Protocol (MGCP), Mauricio Arango, Isaac [25] Media Gateway Control Protocol (MGCP), Mauricio Arango, Isaac
Elliott, Christian Huitema, Scott Pickett, Version 1.0, Elliott, Christian Huitema, Scott Pickett, Version 1.0,
RFC2705. RFC2705.
[26] draft-ietf-Megaco-merged-00.txt, April, 2000, Media Gateway [26] draft-ietf-Megaco-merged-00.txt, April, 2000, Media Gateway
control (Megaco) protocol, Fernando Cuervo, Nancy Greene, Christian control (Megaco) protocol, Fernando Cuervo, Nancy Greene, Christian
Huitema, Abdallah Rayhan, Brian Rosen, John Segers. Huitema, Abdallah Rayhan, Brian Rosen, John Segers.
Rajesh Kumar, Mohamed Mostafa. 87
[27] IP Authentication Header, R. Atkinson, August 1995, RFC1826. [27] IP Authentication Header, R. Atkinson, August 1995, RFC1826.
[28] ITU I.371, Traffic Control and Congestion Control in the BISDN. [28] ITU I.371, Traffic Control and Congestion Control in the BISDN.
[29] ITU E.191, BISDN Numbering and Addressing. [29] ITU E.191, BISDN Numbering and Addressing.
[30] ATM Forum Addressing: Reference Guide, af-ra-0106.000. [30] ATM Forum Addressing: Reference Guide, af-ra-0106.000.
[31] http://www.isi.edu/in-notes/iana/assignments/rtp-parameters [31] http://www.isi.edu/in-notes/iana/assignments/rtp-parameters
for a list of codecs with static payload types. for a list of codecs with static payload types.
skipping to change at line 4166 skipping to change at line 4531
[41] I.365.3, B-ISDN ATM adaptation layer sublayers: service [41] I.365.3, B-ISDN ATM adaptation layer sublayers: service
specific coordination function to provide the specific coordination function to provide the
connection-oriented transport service. connection-oriented transport service.
[42] I.365.4, B-ISDN ATM adaptation layer sublayers: Service specific [42] I.365.4, B-ISDN ATM adaptation layer sublayers: Service specific
convergence sublayer for HDLC applications. convergence sublayer for HDLC applications.
[43] Q.2110, B-ISDN ATM adaptation layer - service specific connection [43] Q.2110, B-ISDN ATM adaptation layer - service specific connection
oriented protocol (SSCOP). oriented protocol (SSCOP).
Rajesh Kumar, Mohamed Mostafa. 69
[44] af-vtoa-0113.000, ATM trunking using AAL2 for narrowband services. [44] af-vtoa-0113.000, ATM trunking using AAL2 for narrowband services.
[45] H.323-2, Packet-based multimedia communications systems. [45] H.323-2, Packet-based multimedia communications systems.
Rajesh Kumar, Mohamed Mostafa. 88
[46] af-vtoa-0083.000, Voice and Telephony Over ATM to the Desktop. [46] af-vtoa-0083.000, Voice and Telephony Over ATM to the Desktop.
[47] I.356, BISDN ATM layer cell transfer performance. [47] I.356, BISDN ATM layer cell transfer performance.
[48] ITU Q.2957, Digital Subscriber Signaling System No. 2, User to user [48] ITU Q.2957, Digital Subscriber Signaling System No. 2, User to user
signaling. signaling.
[49] rfc1305, Network Time Protocol, version 3. [49] rfc1305, Network Time Protocol, version 3.
[50] TIA/EIA/IS-J-STD-025-A, Lawfully Authorized Electronic Surveillance, [50] TIA/EIA/IS-J-STD-025-A, Lawfully Authorized Electronic Surveillance,
May 2000. May 2000.
[51] ITU-T H.222.1, Multimedia multiplex and synchronization for audiovisual [51] ITU-T H.222.1, Multimedia multiplex and synchronization for audiovisual
communication in ATM environments. communication in ATM environments.
[52] af-vmoa-0145.000, Voice and Multimedia over ATM, Loop Emulation Service [52] af-vmoa-0145.000, Voice and Multimedia over ATM, Loop Emulation Service
using AAL2. using AAL2.
[53] FRF.5, Frame Relay/ATM PVC Network Interworking Implementation Agreement. [53] FRF.5, Frame Relay/ATM PVC Network Interworking Implementation Agreement.
[54] FRF.8, Frame Relay/ATM PVC Service Interworking Implementation Agreement. [54] FRF.8.1, Frame Relay/ATM PVC Service Interworking
Implementation Agreement.
[55] FRF.11, Voice over Frame Relay Implementation Agreement. [55] FRF.11, Voice over Frame Relay Implementation Agreement.
[56] rfc2234, Augmented BNF for Syntax Specifications: ABNF [56] rfc2234, Augmented BNF for Syntax Specifications: ABNF.
[57] ITU Q.765.5, Application Transport Mechanism - Bearer Independent
Call Control.
[58] http://www.3gpp.org/ftp/Specs for specifications related to 3GPP,
including AMR codecs.
[59] ITU Q.931, Digital Subscriber Signaling System No. 1: Network Layer.
[60] ITU Q.763, SS7 - ISUP formats and codes.
Acknowledgements Acknowledgements
The authors wish to thank several colleagues at Cisco and in the The authors wish to thank several colleagues at Cisco and in the
industry who have contributed towards the development of these SDP industry who have contributed towards the development of these SDP
conventions, and who have reviewed, implemented and tested these conventions, and who have reviewed, implemented and tested these
constructs. Valuable technical ideas that have been incorporated constructs. Valuable technical ideas that have been incorporated
into this internet draft have been provided by Hisham Abdelhamid, into this internet draft have been provided by Hisham Abdelhamid,
David Auerbach, Robert Biskner, Bruce Buffam, Steve Casner, Alex Clemm, Flemming Andreasen, David Auerbach, Robert Biskner, Bruce Buffam,
Bill Foster, Snehal Karia, Raghu Thirumalai Rajan, Joe Stone, Bruce Steve Casner, Alex Clemm, Bill Foster, Snehal Karia, Raghu Thirumalai
Thompson, Dan Wing and Ken Young of Cisco, Michael Brown, Rade Rajan, Joe Stone, Bruce Thompson, Dan Wing and Ken Young of Cisco,
Gvozdanovic, Graeme Gibbs, Tom-PT Taylor, Mark Watson Michael Brown, Rade Gvozdanovic, Graeme Gibbs, Tom-PT Taylor, Mark Watson
and Sophia Scoggins of Nortel Networks, Brian Rosen, Tim Dwight and Michael and Sophia Scoggins of Nortel Networks, Brian Rosen, Tim Dwight and Michael
Mackey of Marconi, Ed Guy and Petros Mouchtaris of Telcordia, Christian Mackey of Marconi, Ed Guy and Petros Mouchtaris of Telcordia, Christian
Groves of Ericsson, Charles Eckel of Vovida Networks, Tom Jepsen and Groves of Ericsson, Charles Eckel of Vovida Networks, Tom Jepsen, Dal Chohan
Chris Gallon of Fujitsu, Mahamood Hussain of Hughes Software Systems, and Chris Gallon of Fujitsu, Mahamood Hussain of Hughes Software Systems,
Sean Sheedy of nCUBE Corporation and Narendra Tulpule of Intel. The authors Sean Sheedy of nCUBE Corporation, Narendra Tulpule of Intel, and
also wish to thank the ISC device control group, and
the MMUSIC and MEGACO subgroups of the IETF, especially Bill Foster, Jeorg Rajesh Kumar, Mohamed Mostafa. 89
Ott, Sean Sheedy and Brian Rosen for their help in the preparation of this Albrecht Schwarz of Alcatel. The authors also wish to thank the
document. Finally, thanks are due to Narendra Tulpule of Intel whose ABNF ISC device control group, and the MMUSIC and MEGACO subgroups of the
grammar was adapted for this document. IETF, especially Bill Foster, Joerg Ott, Sean Sheedy and Brian Rosen
for their help in the preparation of this document. Finally, thanks are
due to Narendra Tulpule of Intel whose ABNF grammar was adapted for
this document.
Authors' Addresses Authors' Addresses
Rajesh Kumar Rajesh Kumar
Cisco Systems, Inc. Cisco Systems, Inc.
M/S SJC01/3 M/S SJC01/3
170 West Tasman Drive 170 West Tasman Drive
San Jose, CA 95134-1706 San Jose, CA 95134-1706
Phone: 1-800-250-4800 Phone: 1-800-250-4800
Email: rkumar@cisco.com Email: rkumar@cisco.com
Rajesh Kumar, Mohamed Mostafa. 70
Mohamed Mostafa Mohamed Mostafa
Cisco Systems, Inc. Cisco Systems, Inc.
M/S SJC01/3 M/S SJC01/3
170 West Tasman Drive 170 West Tasman Drive
San Jose, CA 95134-1706 San Jose, CA 95134-1706
Phone: 1-800-250-4800 Phone: 1-800-250-4800
Email: mmostafa@cisco.com Email: mmostafa@cisco.com
Rajesh Kumar, Mohamed Mostafa. 90
Full Copyright Statement Full Copyright Statement
Copyright (C) The Internet Society (March 2, 2000). All Rights Copyright (C) The Internet Society (March 2, 2000). All Rights
Reserved. Reserved.
This document and translations of it may be copied and furnished to This document and translations of it may be copied and furnished to
others, and derivative works that comment on or otherwise explain it others, and derivative works that comment on or otherwise explain it
or assist in its implementation may be prepared, copied, published or assist in its implementation may be prepared, copied, published
and distributed, in whole or in part, without restriction of any and distributed, in whole or in part, without restriction of any
kind, provided that the above copyright notice and this paragraph kind, provided that the above copyright notice and this paragraph
skipping to change at line 4267 skipping to change at line 4647
The limited permissions granted above are perpetual and will not be The limited permissions granted above are perpetual and will not be
revoked by the Internet Society or its successors or assigns. revoked by the Internet Society or its successors or assigns.
This document and the information contained herein is provided on an This document and the information contained herein is provided on an
"AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION
HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE." MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE."
Rajesh Kumar, Mohamed Mostafa. 71 Rajesh Kumar, Mohamed Mostafa. 91
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