One document matched: draft-camarillo-mmusic-separate-streams-00.txt

Internet Engineering Task Force                                   SIP WG
Internet Draft                                              G. Camarillo
                                                                Ericsson
                                                               A. Monrad
                                                                Ericsson
draft-camarillo-mmusic-separate-streams-00.txt
May 22, 2002
Expires: December 2002


         Mapping of Media Streams to Resource Reservation Flows

STATUS OF THIS MEMO

   This document is an Internet-Draft and is in full conformance with
   all provisions of Section 10 of RFC2026.

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Abstract

   This document defines an extension to the SDP grouping framework. It
   allows to request that different media streams are mapped into
   different resource reservation flows.












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                           Table of Contents



   1          Introduction ........................................    3
   1.1        Terminology .........................................    3
   2          KIS Semantics .......................................    3
   3          Example .............................................    3
   4          IANA Considerations .................................    4
   5          Security Considerations .............................    4
   6          Authors' Addresses ..................................    4
   7          Normative References ................................    5
   8          Informative References ..............................    5



































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1 Introduction

   Resource reservation protocols assign network resources to particular
   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 and
   provide it with the Quality of Service (QoS) corresponding to that
   flow. Routers typically use the source and the destination IP
   addresses and port numbers to filter packets.

   Multimedia sessions typically contain multiple media streams (e.g. an
   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
   resource reservation flows. This mapping can be performed in
   different ways. Two possibilities are to map all the media streams to
   a single resource reservation flow and to map every single media
   stream to a different resource reservation flow. Some applications
   require that the latter type of mapping is performed (i.e., a single
   media stream is mapped to a single resource reservation flow). This
   document defines the syntax needed to express that need in SDP [1].
   For this purpose, we make use of the SDP grouping framework [2] and
   define a new "semantics" attribute called KIS (Keep It Separate).

1.1 Terminology

   In this document, the key words "MUST", "MUST NOT", "REQUIRED",
   "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY",
   and "OPTIONAL" are to be interpreted as described in RFC 2119 [3] and
   indicate requirement levels for compliant SIP implementations.

2 KIS Semantics

   We define a new "semantics" attribute within the SDP grouping
   framework [2]: KIS (Keep It Separate).

   Media lines grouped using KIS semantics SHOULD NOT be mapped into the
   same resource reservation flow. A different resource reservation flow
   SHOULD be used (or established) for each media line of the KIS group.

3 Example

   A user agent receives a SIP [4] INVITE with the SDP below:



            v=0
            o=Laura 289083124 289083124 IN IP4 one.example.com
            t=0 0
            c=IN IP4 192.0.0.1



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            a=group:KIS 1 2
            m=audio 30000 RTP/AVP 0
            a=mid:1
            m=video 30002 RTP/AVP 31
            a=mid:2



   This user agent uses RSVP [5] to perform resource reservation. Since
   both media streams are part of a KIS group, the user agent will
   establish two different RSVP sessions; one for the audio stream and
   one for the video stream. An RSVP session is defined by the triple:
   (DestAddress, ProtocolId[, DstPort]). Table 1 shows the parameters
   used to establish both RSVP sessions.


             Session Number  DestAddress  ProtocolId  DstPort
             ________________________________________________
                   1          192.0.0.1      UDP       30000
                   2          192.0.0.1      UDP       30002


   Table 1: Parameters needed to establish both RSVP sessions


   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
   map both media streams into the same RSVP session.

4 IANA Considerations

   IANA needs to register the following new "semantics" attribute for
   the SDP grouping framework [2]:


           KIS: Keep It Separate



5 Security Considerations

   An attacker adding group lines using the KIS semantics to an SDP
   session description could force a user agent to establish a larger
   number of resource reservation flows than needed. It is thus
   RECOMMENDED that some kind of integrity protection is applied to SDP
   session descriptions.

6 Authors' Addresses



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   Gonzalo Camarillo
   Ericsson
   Advanced Signalling Research Lab.
   FIN-02420 Jorvas
   Finland
   electronic mail:  Gonzalo.Camarillo@ericsson.com

   Atle Monrad
   Ericsson
   N-4898 Grimstad
   Norway
   electronic mail:  atle.monrad@ericsson.com

7 Normative References

   [1] M. Handley and V. Jacobson, "SDP: session description protocol,"
   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.

8 Informative References

   [4] J. Rosenberg, H. Schulzrinne,  et al.  , "SIP: Session initiation
   protocol," Internet Draft, Internet Engineering Task Force, Feb.
   2002.  Work in progress.

   [5] R. Braden, Ed., L. Zhang, S. Berson, S. Herzog, and S. Jamin,
   "Resource ReSerVation protocol (RSVP) -- version 1 functional
   specification," RFC 2205, Internet Engineering Task Force, Sept.
   1997.


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