draft-ietf-mmusic-reservation-flows-01.txt   rfc3524.txt 
Internet Engineering Task Force SIP WG Network Working Group G. Camarillo
Internet Draft G. Camarillo Request for Comments: 3524 A. Monrad
Ericsson Category: Standards Track Ericsson
A. Monrad April 2003
Ericsson
draft-ietf-mmusic-reservation-flows-01.txt
October 29, 2002
Expires: April 2003
Mapping of Media Streams to Resource Reservation Flows Mapping of Media Streams to Resource Reservation Flows
STATUS OF THIS MEMO Status of this Memo
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Abstract Abstract
This document defines an extension to the SDP grouping framework. It This document defines an extension to the Session Description
allows requesting that a group of media streams is mapped into a Protocol (SDP) grouping framework. It allows requesting a group of
single resource reservation flow. media streams to be mapped into a single resource reservation flow.
The SDP syntax needed is defined, as well as a new "semantics"
attribute called Single Reservation Flow (SRF).
Table of Contents Table of Contents
1 Introduction ........................................ 3 1. Introduction ........................................ 2
1.1 Terminology ......................................... 3 1.1 Terminology .................................... 2
2 SRF Semantics ....................................... 3 2. SRF Semantics ....................................... 2
3 Applicability Statement ............................. 4 3. Applicability Statement ............................. 3
4 Examples ............................................ 4 4. Examples ............................................ 3
5 IANA Considerations ................................. 5 5. IANA Considerations ................................. 4
6 Security Considerations ............................. 5 6. Security Considerations ............................. 4
7 Acknowledgements .................................... 5 7. Acknowledgements .................................... 4
8 Authors' Addresses .................................. 5 8. Normative References ................................ 5
9 Normative References ................................ 6 9. Informative References .............................. 5
10 Informative References .............................. 6 10. Authors' Addresses .................................. 5
11. Full Copyright Statement ............................ 6
1 Introduction 1. Introduction
Resource reservation protocols assign network resources to particular Resource reservation protocols assign network resources to particular
flows of IP packets. When a router receives an IP packet, it applies flows of IP packets. When a router receives an IP packet, it applies
a filter in order to map the packet to the flow it belongs. The a filter in order to map the packet to the flow it belongs. The
router provides the IP packet with the Quality of Service (QoS) router provides the IP packet with the Quality of Service (QoS)
corresponding to its flow. Routers typically use the source and the corresponding to its flow. Routers typically use the source and the
destination IP addresses and port numbers to filter packets. destination IP addresses and port numbers to filter packets.
Multimedia sessions typically contain multiple media streams (e.g., Multimedia sessions typically contain multiple media streams (e.g. an
an audio stream and a video stream). In order to provide QoS for a audio stream and a video stream). In order to provide QoS for a
multimedia session it is necessary to map all the media streams to multimedia session it is necessary to map all the media streams to
resource reservation flows. This mapping can be performed in resource reservation flows. This mapping can be performed in
different ways. Two possible ways are to map all the media streams to different ways. Two possible ways are to map all the media streams
a single resource reservation flow and to map every single media to a single resource reservation flow or to map every single media
stream to a different resource reservation flow. Some applications stream to a different resource reservation flow. Some applications
require that the former type of mapping is performed while other require that the former type of mapping is performed while other
applications require the latter. It is even possible that a mixture applications require the latter. It is even possible that a mixture
of both mappings is required for a particular media session. For of both mappings is required for a particular media session. For
instance, a multimedia session with three media streams might require instance, a multimedia session with three media streams might require
that two of them are mapped into a single reservation flow while the that two of them are mapped into a single reservation flow while the
third media stream uses a second reservation flow. third media stream uses a second reservation flow.
This document defines the SDP [1] syntax needed to express how media This document defines the SDP [1] syntax needed to express how media
streams need to be mapped into reservation flows. For this purpose, streams need to be mapped into reservation flows. For this purpose,
we use the SDP grouping framework [2] and define a new "semantics" we use the SDP grouping framework [2] and define a new "semantics"
attribute called SRF (Single Reservation Flow). attribute called Single Reservation Flow (SRF).
1.1 Terminology 1.1 Terminology
In this document, the key words "MUST", "MUST NOT", "REQUIRED", In this document, the key words "MUST", "MUST NOT", "REQUIRED",
"SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY",
and "OPTIONAL" are to be interpreted as described in RFC 2119 [3] and and "OPTIONAL" are to be interpreted as described in BCP 14, RFC 2119
indicate requirement levels for compliant SIP implementations. [3] and indicate requirement levels for compliant SIP
implementations.
2 SRF Semantics 2. SRF Semantics
We define a new "semantics" attribute within the SDP grouping We define a new "semantics" attribute within the SDP grouping
framework [2]: SRF (Single Reservation Flow). framework [2]: Single Reservation Flow (SRF).
Media lines grouped using SRF semantics SHOULD be mapped into the Media lines grouped using SRF semantics SHOULD be mapped into the
same resource reservation flow. Media lines that do not belong to a same resource reservation flow. Media lines that do not belong to a
particular SRF group SHOULD NOT be mapped into the reservation flow particular SRF group SHOULD NOT be mapped into the reservation flow
used for that SRF group. used for that SRF group.
Note that an SRF group MAY consist of a single media line. In that Note that an SRF group MAY consist of a single media line. In that
case, following the definition above, that media line will be mapped case, following the definition above, that media line will be mapped
into one reservation flow. That reservation flow will carry traffic into one reservation flow. That reservation flow will carry traffic
from that media line, and from no other media lines. from that media line, and from no other media lines.
3 Applicability Statement 3. Applicability Statement
The way resource reservation works in some scenarios makes it The way resource reservation works in some scenarios makes it
unnecessary the use of the mechanism described in this document. Some unnecessary to use the mechanism described in this document. Some
resource reservation protocols allow the entity generating the SDP resource reservation protocols allow the entity generating the SDP
session description to allocate resources in both directions (i.e., session description to allocate resources in both directions (i.e.,
sendrecv) for the session. In this case, the generator of the session sendrecv) for the session. In this case, the generator of the
description can chose any particular mapping of media flows and session description can chose any particular mapping of media flows
reservation flows. and reservation flows.
The mechanism described in this document is useful when the remote The mechanism described in this document is useful when the remote
party needs to be involved in the resource reservation. party needs to be involved in the resource reservation.
4 Examples 4. Examples
For this example, we have chosen to use SIP [4] to transport SDP For this example, we have chosen to use SIP [4] to transport SDP
sessions and RSVP [5] to establish reservation flows. However, other sessions and RSVP [5] to establish reservation flows. However, other
protocols or mechanisms could be used instead without affecting the protocols or mechanisms could be used instead without affecting the
SDP syntax. SDP syntax.
A user agent receives a SIP INVITE with the SDP below: A user agent receives a SIP INVITE with the SDP below:
v=0 v=0
o=Laura 289083124 289083124 IN IP4 one.example.com o=Laura 289083124 289083124 IN IP4 one.example.com
t=0 0 t=0 0
c=IN IP4 192.0.0.1 c=IN IP4 192.0.0.1
a=group:SRF 1 2 a=group:SRF 1 2
m=audio 30000 RTP/AVP 0 m=audio 30000 RTP/AVP 0
a=mid:1 a=mid:1
m=video 30002 RTP/AVP 31 m=video 30002 RTP/AVP 31
a=mid:2 a=mid:2
This user agent uses RSVP to perform resource reservation. Since both This user agent uses RSVP to perform resource reservation. Since
media streams are part of a SRF group, the user agent will establish both media streams are part of an SRF group, the user agent will
a single RSVP session. An RSVP session is defined by the triple: establish a single RSVP session. An RSVP session is defined by the
(DestAddress, ProtocolId[, DstPort]). Table 1 shows the parameters triple: (DestAddress, ProtocolId[, DstPort]). Table 1 shows the
used to establish the RSVP session. parameters used to establish the RSVP session.
If the same user agent received an SDP session description with the If the same user agent received an SDP session description with the
same media streams but without the group line, it would be free to same media streams but without the group line, it would be free to
map the two media streams into two different RSVP sessions. map the two media streams into two different RSVP sessions.
Session Number DestAddress ProtocolId DstPort Session Number DestAddress ProtocolId DstPort
________________________________________________ ________________________________________________
1 192.0.0.1 UDP any 1 192.0.0.1 UDP any
Table 1: Parameters needed to establish the RSVP session Table 1: Parameters needed to establish the RSVP session
5 IANA Considerations 5. IANA Considerations
IANA needs to register the following new "semantics" attribute for IANA has registered the following new "semantics" attribute for the
the SDP grouping framework [2]: SDP grouping framework [2]. It has been registered in the SDP
parameters registry (http://www.iana.org/assignments/sdp-parameters)
under Semantics for the "group" SDP Attribute:
Semantics Token Reference Semantics Token Reference
------------------- ----- --------- ------------------- ----- ---------
Single Reservation flow SRF [RFCxxxx] Single Reservation flow SRF [RFC3524]
It should be registered in the SDP parameters registry
(http://www.iana.org/assignments/sdp-parameters) under Semantics for
the "group" SDP Attribute.
6 Security Considerations 6. Security Considerations
An attacker adding group lines using the SRF semantics to an SDP An attacker adding group lines using the SRF semantics to an SDP
session description could force a user agent to establish a larger or session description could force a user agent to establish a larger or
a smaller number of resource reservation flows than needed. This a smaller number of resource reservation flows than needed. This
could consume extra resources in the end-point or degrade the quality could consume extra resources in the end-point or degrade the quality
of service for a particular session. It is thus RECOMMENDED that some of service for a particular session. It is thus STRONGLY RECOMMENDED
kind of integrity protection is applied to SDP session descriptions. that integrity protection be applied to the SDP session descriptions.
For session descriptions carried in SIP, S/MIME is the natural choice
to provide such end-to-end integrity protection, as described in RFC
3261 [4]. Other applications MAY use a different form of integrity
protection.
7 Acknowledgements 7. Acknowledgements
Jonathan Rosenberg provided useful comments about the applicability Jonathan Rosenberg provided useful comments about the applicability
of the mechanism described in this document. of the mechanism described in this document.
8 Authors' Addresses 8. Normative References
[1] Handley, M. and V. Jacobson, "SDP: Session Description
Protocol", RFC 2327, April 1998.
[2] Camarillo, G., Eriksson, G., Holler, J. and H. Schulzrinne,
"Grouping of Media Lines in the Session Description Protocol
(SDP)", December 2002.
[3] Bradner, S., "Key words for use in RFCs to indicate requirement
levels", BCP 14, RFC 2119, March 1997.
9. Informative References
[4] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston, A.,
Peterson, J., Sparks, R., Handley, M. and E. Schooler, "SIP:
Session Initiation Protocol", RFC 3261, June 2002.
[5] Braden, R., Zhang, L., Berson, S., Herzog, S. and S. Jamin,
"Resource ReSerVation protocol (RSVP) -- Version 1 Functional
Specification", RFC 2205, September 1997.
10. Authors' Addresses
Gonzalo Camarillo Gonzalo Camarillo
Ericsson Ericsson
Advanced Signalling Research Lab. Advanced Signalling Research Lab.
FIN-02420 Jorvas FIN-02420 Jorvas
Finland Finland
electronic mail: Gonzalo.Camarillo@ericsson.com
EMail: Gonzalo.Camarillo@ericsson.com
Atle Monrad Atle Monrad
Ericsson Ericsson
N-4898 Grimstad N-4898 Grimstad
Norway Norway
electronic mail: atle.monrad@ericsson.com
9 Normative References
[1] M. Handley and V. Jacobson, "SDP: session description protocol," EMail: atle.monrad@ericsson.com
RFC 2327, Internet Engineering Task Force, Apr. 1998.
[2] G. Camarillo, J. Holler, G. Eriksson, and H. Schulzrinne,
"Grouping of m lines in SDP," Internet Draft, Internet Engineering
Task Force, Feb. 2002. Work in progress.
[3] S. Bradner, "Key words for use in RFCs to indicate requirement
levels," RFC 2119, Internet Engineering Task Force, Mar. 1997.
10 Informative References
[4] J. Rosenberg, H. Schulzrinne, G. Camarillo, A. Johnston, J.
Peterson, R. Sparks, M. Handley, and E. Schooler, "SIP: session
initiation protocol," RFC 3261, Internet Engineering Task Force, June
2002.
[5] "Resource ReSerVation protocol (RSVP) -- version 1 functional
specification," RFC 2205, Internet Engineering Task Force, Sept.
1997.
Full Copyright Statement 11. Full Copyright Statement
Copyright (c) The Internet Society (2002). All Rights Reserved. Copyright (C) The Internet Society (2003). All Rights Reserved.
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others, and derivative works that comment on or otherwise explain it others, and derivative works that comment on or otherwise explain it
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and distributed, in whole or in part, without restriction of any and distributed, in whole or in part, without restriction of any
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included on all such copies and derivative works. However, this included on all such copies and derivative works. However, this
document itself may not be modified in any way, such as by removing document itself may not be modified in any way, such as by removing
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skipping to change at line 244 skipping to change at page 6, line 32
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Acknowledgement
Funding for the RFC Editor function is currently provided by the
Internet Society.
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