draft-ietf-fecframe-sdp-elements-09.txt   draft-ietf-fecframe-sdp-elements-10.txt 
FEC Framework A. Begen FEC Framework A. Begen
Internet-Draft Cisco Internet-Draft Cisco
Intended status: Standards Track September 26, 2010 Intended status: Standards Track October 9, 2010
Expires: March 30, 2011 Expires: April 12, 2011
Session Description Protocol Elements for FEC Framework Session Description Protocol Elements for FEC Framework
draft-ietf-fecframe-sdp-elements-09 draft-ietf-fecframe-sdp-elements-10
Abstract Abstract
This document specifies the use of Session Description Protocol (SDP) This document specifies the use of Session Description Protocol (SDP)
to describe the parameters required to signal the Forward Error to describe the parameters required to signal the Forward Error
Correction (FEC) Framework Configuration Information between the Correction (FEC) Framework Configuration Information between the
sender(s) and receiver(s). This document also provides examples that sender(s) and receiver(s). This document also provides examples that
show the semantics for grouping multiple source and repair flows show the semantics for grouping multiple source and repair flows
together for the applications that simultaneously use multiple together for the applications that simultaneously use multiple
instances of the FEC Framework. instances of the FEC Framework.
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Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on March 30, 2011. This Internet-Draft will expire on April 12, 2011.
Copyright Notice Copyright Notice
Copyright (c) 2010 IETF Trust and the persons identified as the Copyright (c) 2010 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
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4. SDP Elements 4. SDP Elements
This section defines the SDP elements that MUST be used to describe This section defines the SDP elements that MUST be used to describe
the FEC Framework Configuration Information in multimedia sessions by the FEC Framework Configuration Information in multimedia sessions by
the CDPs that choose SDP [RFC4566] as their session description the CDPs that choose SDP [RFC4566] as their session description
protocol. Example SDP descriptions can be found in Section 6. protocol. Example SDP descriptions can be found in Section 6.
4.1. Transport Protocol Identifiers 4.1. Transport Protocol Identifiers
This specification defines a class of new transport protocol This specification defines a new transport protocol identifier for
identifiers for SDP media descriptions. For all existing identifiers the FEC schemes that take a UDP-formatted input stream and append an
<proto> (listed in the table for the 'proto' field in the Session Explicit Source FEC Payload ID as described in Section 5.3 of
Description Protocol (SDP) Parameters registry), this specification [I-D.ietf-fecframe-framework] to generate a source flow. This new
defines the identifier 'FEC/<proto>'. This identifier MAY be used as protocol identifier is 'FEC/UDP'. To use input streams that are
the transport protocol identifier in the media descriptions for the formatted according to another <proto> (as listed in the table for
source data to indicate that the FEC Source Packet format defined in the 'proto' field in the Session Description Protocol (SDP)
Section 5.3 of [I-D.ietf-fecframe-framework] is used, where the Parameters registry), the corresponding 'FEC/<proto>' transport
original transport payload field is formatted according to <proto>. protocol identifier MUST be registered with IANA by following the
However, if the FEC scheme does not use the Explicit Source FEC instructions specified in [RFC4566].
Note that if an FEC scheme does not use the Explicit Source FEC
Payload ID as described in Section 4.1 of Payload ID as described in Section 4.1 of
[I-D.ietf-fecframe-framework], then the original transport protocol [I-D.ietf-fecframe-framework], then the original transport protocol
identifier MUST be used to support backward compatibility with the identifier MUST be used to support backward compatibility with the
receivers that do not support FEC at all. receivers that do not support FEC at all.
This specification also defines another transport protocol This specification also defines another transport protocol
identifier, 'UDP/FEC', to indicate the FEC Repair Packet format identifier, 'UDP/FEC', to indicate the FEC Repair Packet format
defined in Section 5.4 of [I-D.ietf-fecframe-framework]. defined in Section 5.4 of [I-D.ietf-fecframe-framework]. For
detailed registration information, refer to Section 8.1.
4.2. Media Stream Grouping 4.2. Media Stream Grouping
In FEC Framework, the 'group' attribute and the FEC grouping In FEC Framework, the 'group' attribute and the FEC grouping
semantics defined in [RFC5888] and [I-D.ietf-mmusic-rfc4756bis], semantics defined in [RFC5888] and [RFC5956], respectively are used
respectively are used to associate source and repair flows together. to associate source and repair flows together.
4.3. Source IP Addresses 4.3. Source IP Addresses
The 'source-filter' attribute of SDP ("a=source-filter") as defined The 'source-filter' attribute of SDP ("a=source-filter") as defined
in [RFC4570] is used to express the source addresses or fully in [RFC4570] is used to express the source addresses or fully
qualified domain names in the FEC Framework. qualified domain names in the FEC Framework.
4.4. Source Flows 4.4. Source Flows
The FEC Framework allows that multiple source flows MAY be grouped The FEC Framework allows that multiple source flows MAY be grouped
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flow-preference = "preference-lvl=" preference-level-of-the-flow flow-preference = "preference-lvl=" preference-level-of-the-flow
preference-level-of-the-flow = 1*DIGIT preference-level-of-the-flow = 1*DIGIT
sender-side-scheme-specific = "ss-fssi=" sender-info sender-side-scheme-specific = "ss-fssi=" sender-info
sender-info = element *( "," element ) sender-info = element *( "," element )
element = name ":" value element = name ":" value
name = token name = token
token = 1*<any CHAR except CTLs or separators> token = 1*<any CHAR except CTLs or separators>
value = *<any CHAR except CTLs or separators> value = *<any CHAR except CTLs or separators>
separator = "(" / ")" / "<" / ">" / "@" separator = "(" / ")" / "<" / ">" / "@"
/ "," / ";" / ":" / "\" / <"> / "," / ";" / ":" / "\" / DQUOTE
/ "/" / "[" / "]" / "?" / "=" / "/" / "[" / "]" / "?" / "="
/ "{" / "}" / SP / HTAB / "{" / "}" / SP / HTAB
scheme-specific = "fssi=" scheme-info scheme-specific = "fssi=" scheme-info
scheme-info = element *( "," element ) scheme-info = element *( "," element )
element = name ":" value
The REQUIRED parameter 'encoding-id' is used to identify the FEC The REQUIRED parameter 'encoding-id' is used to identify the FEC
scheme used to generate this repair flow. These identifiers (in the scheme used to generate this repair flow. These identifiers (in the
range of [0 - 255]) are registered by the FEC schemes that use the range of [0 - 255]) are registered by the FEC schemes that use the
FEC Framework and are maintained by IANA. FEC Framework and are maintained by IANA.
The OPTIONAL parameter 'preference-lvl' is used to indicate the The OPTIONAL parameter 'preference-lvl' is used to indicate the
preferred order of using the repair flows. The exact usage of the preferred order of using the repair flows. The exact usage of the
parameter 'preference-lvl' and the pertaining rules MAY be defined by parameter 'preference-lvl' and the pertaining rules MAY be defined by
the FEC scheme or the CDP. If the parameter 'preference-lvl' does the FEC scheme or the CDP. If the parameter 'preference-lvl' does
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5.2. Offer/Answer Model Considerations 5.2. Offer/Answer Model Considerations
In unicast-based applications, a sender and receiver MAY adopt the In unicast-based applications, a sender and receiver MAY adopt the
Offer/Answer Model [RFC3264] to set the FEC Framework Configuration Offer/Answer Model [RFC3264] to set the FEC Framework Configuration
Information. In this case, the sender offers the options available Information. In this case, the sender offers the options available
to this particular receiver and the receiver answers back to the to this particular receiver and the receiver answers back to the
sender with its choice(s). sender with its choice(s).
Receivers supporting the SDP Capability Negotiation Framework Receivers supporting the SDP Capability Negotiation Framework
[I-D.ietf-mmusic-sdp-capability-negotiation] MAY also use this [RFC5939] MAY also use this framework to negotiate all or a subset of
framework to negotiate all or a subset of the FEC Framework the FEC Framework parameters.
parameters.
The backward compatibility in Offer/Answer Model is handled as The backward compatibility in Offer/Answer Model is handled as
specified in [I-D.ietf-mmusic-rfc4756bis]. specified in [RFC5956].
6. SDP Examples 6. SDP Examples
This section provides SDP examples that can be used by the FEC This section provides SDP examples that can be used by the FEC
Framework. Framework.
[RFC5888] defines the media stream identification attribute ('mid') [RFC5888] defines the media stream identification attribute ('mid')
as a token in ABNF. In contrast, the identifiers for the source as a token in ABNF. In contrast, the identifiers for the source
flows MUST be integers and SHOULD be allocated starting from zero and flows MUST be integers and SHOULD be allocated starting from zero and
increasing by one for each flow. To avoid any ambiguity, using the increasing by one for each flow. To avoid any ambiguity, using the
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8.1. Registration of Transport Protocols 8.1. Registration of Transport Protocols
This specification updates the Session Description Protocol (SDP) This specification updates the Session Description Protocol (SDP)
Parameters registry as defined in Section 8.2.2 of [RFC4566]. Parameters registry as defined in Section 8.2.2 of [RFC4566].
Specifically, it adds the following values to the table for the Specifically, it adds the following values to the table for the
'proto' field. 'proto' field.
Type SDP Name Reference Type SDP Name Reference
------ ---------- ----------- ------ ---------- -----------
proto FEC/UDP [RFCXXXX]
proto UDP/FEC [RFCXXXX] proto UDP/FEC [RFCXXXX]
This specification also defines a class of new transport protocol This specification also defines a class of new transport protocol
identifiers. For all existing identifiers <proto> (listed in the identifiers. For all existing identifiers <proto> (listed in the
table for the 'proto' field in the Session Description Protocol (SDP) table for the 'proto' field in the Session Description Protocol (SDP)
Parameters registry), this specification defines the identifier 'FEC/ Parameters registry), this specification defines the identifier 'FEC/
<proto>'. <proto>'.
8.2. Registration of SDP Attributes 8.2. Registration of SDP Attributes
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[RFC4566] Handley, M., Jacobson, V., and C. Perkins, "SDP: Session [RFC4566] Handley, M., Jacobson, V., and C. Perkins, "SDP: Session
Description Protocol", RFC 4566, July 2006. Description Protocol", RFC 4566, July 2006.
[RFC4570] Quinn, B. and R. Finlayson, "Session Description Protocol [RFC4570] Quinn, B. and R. Finlayson, "Session Description Protocol
(SDP) Source Filters", RFC 4570, July 2006. (SDP) Source Filters", RFC 4570, July 2006.
[RFC5888] Camarillo, G. and H. Schulzrinne, "The Session Description [RFC5888] Camarillo, G. and H. Schulzrinne, "The Session Description
Protocol (SDP) Grouping Framework", RFC 5888, June 2010. Protocol (SDP) Grouping Framework", RFC 5888, June 2010.
[I-D.ietf-mmusic-rfc4756bis] [RFC5956] Begen, A., "Forward Error Correction Grouping Semantics in
Begen, A., "Forward Error Correction Grouping Semantics in the Session Description Protocol", RFC 5956,
Session Description Protocol", September 2010.
draft-ietf-mmusic-rfc4756bis-10 (work in progress),
June 2010.
[RFC3890] Westerlund, M., "A Transport Independent Bandwidth [RFC3890] Westerlund, M., "A Transport Independent Bandwidth
Modifier for the Session Description Protocol (SDP)", Modifier for the Session Description Protocol (SDP)",
RFC 3890, September 2004. RFC 3890, September 2004.
[RFC5234] Crocker, D. and P. Overell, "Augmented BNF for Syntax [RFC5234] Crocker, D. and P. Overell, "Augmented BNF for Syntax
Specifications: ABNF", STD 68, RFC 5234, January 2008. Specifications: ABNF", STD 68, RFC 5234, January 2008.
[RFC3264] Rosenberg, J. and H. Schulzrinne, "An Offer/Answer Model [RFC3264] Rosenberg, J. and H. Schulzrinne, "An Offer/Answer Model
with Session Description Protocol (SDP)", RFC 3264, with Session Description Protocol (SDP)", RFC 3264,
June 2002. June 2002.
10.2. Informative References 10.2. Informative References
[I-D.ietf-fecframe-config-signaling] [I-D.ietf-fecframe-config-signaling]
Asati, R., "Methods to convey FEC Framework Configuration Asati, R., "Methods to convey FEC Framework Configuration
Information", draft-ietf-fecframe-config-signaling-03 Information", draft-ietf-fecframe-config-signaling-03
(work in progress), June 2010. (work in progress), June 2010.
[I-D.ietf-mmusic-sdp-capability-negotiation] [RFC5939] Andreasen, F., "Session Description Protocol (SDP)
Andreasen, F., "SDP Capability Negotiation", Capability Negotiation", RFC 5939, September 2010.
draft-ietf-mmusic-sdp-capability-negotiation-13 (work in
progress), March 2010.
Author's Address Author's Address
Ali Begen Ali Begen
Cisco Cisco
181 Bay Street 181 Bay Street
Toronto, ON M5J 2T3 Toronto, ON M5J 2T3
Canada Canada
Email: abegen@cisco.com Email: abegen@cisco.com
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