Internet DRAFT - draft-petithuguenin-mmusic-ice-attributes-level
draft-petithuguenin-mmusic-ice-attributes-level
MMUSIC M. Petit-Huguenin
Internet-Draft Impedance Mismatch
Updates: 5245 (if approved) October 8, 2012
Intended status: Standards Track
Expires: April 11, 2013
Media level ice-options SDP attribute
draft-petithuguenin-mmusic-ice-attributes-level-04
Abstract
This document normatively updates RFC 5245 by redefining the ice-
options SDP attribute as a session-level and media-level attribute.
Status of this Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. This document may not be modified,
and derivative works of it may not be created, except to format it
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than English.
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This Internet-Draft will expire on April 11, 2013.
Copyright Notice
Copyright (c) 2012 IETF Trust and the persons identified as the
document authors. All rights reserved.
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described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. The ice-options Attribute . . . . . . . . . . . . . . . . . . 3
4. The ice-lite Attribute . . . . . . . . . . . . . . . . . . . . 3
5. The ice-mismatch Attribute . . . . . . . . . . . . . . . . . . 4
6. Specific Aggregation Rule for the rtp+ecn ICE Option . . . . . 4
7. Security Considerations . . . . . . . . . . . . . . . . . . . 4
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4
9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 4
10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 4
10.1. Normative References . . . . . . . . . . . . . . . . . . 4
10.2. Informative References . . . . . . . . . . . . . . . . . 5
Appendix A. Examples . . . . . . . . . . . . . . . . . . . . . . 5
A.1. Aggregating media all supporting ICE . . . . . . . . . . 5
A.2. Aggregating media partially supporting ICE . . . . . . . 8
Appendix B. Analysis of similar issues in other attributes . . . 11
B.1. The type:broadcast Attribute . . . . . . . . . . . . . . 12
B.2. The charset Attribute . . . . . . . . . . . . . . . . . . 12
B.3. The tool Attribute . . . . . . . . . . . . . . . . . . . 12
B.4. The ipbcp, bcastversion, 3GPP-Integrity-Key,
3GPP-SDP-Auth, alt-group, PSCid, bc_service,
bc_program and bc_service_package Attributes . . . . . . 13
Appendix C. Release notes . . . . . . . . . . . . . . . . . . . . 13
C.1. Modifications between -04 and -03 . . . . . . . . . . . . 13
C.2. Design Notes . . . . . . . . . . . . . . . . . . . . . . 13
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 13
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1. Introduction
ICE [RFC5245] defines the ice-options SDP attribute as session-level
only attribute, but when ICE is used with disaggregated media (see
section 3 of [I-D.loreto-splices-disaggregated-media] ), there is a
possibility that different media use different ICE implementations
and/or different networks, and so these different media will require
different values for this attribute.
As an example, the ice-options attribute value "rtp+ecn" (defined in
[RFC6679] ) signals ECN capability. Two aggregated media using two
different RTP implementations may want to use different values for
this attribute.
Note that there is a similar problem for the ice-lite attribute but
unfortunately it does not seem possible to design a way to use the
ice-lite attribute at the media level that is compatible with legacy
implementations that recognize only the session-level attribute.
2. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119] .
3. The ice-options Attribute
The ice-options attribute is redefined by this document as a session-
level and media-level attribute.
All future new ICE options MUST also define how media-level ICE
options using this new value are aggregated to eventually generate
the value of the session-level ICE option, so legacy implementations
that only recognize session-level ICE options can interoperate with
implementations that recognize ICE options at both levels.
Before applying this specific aggregation rule, the session-level
ice-options attribute MUST be copied as media-level attribute in each
media.
4. The ice-lite Attribute
The ice-lite attribute is not redefined by this specification.
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5. The ice-mismatch Attribute
[RFC5245] section 15.3 defines this attribute as been media level,
which seems correct, but section 21.1.4 erroneously registered this
attribute in IANA as session level. An errata [1] has been filled
and the IANA registry has been accordingly fixed.
6. Specific Aggregation Rule for the rtp+ecn ICE Option
If all aggregated media using ICE contain a media-level "rtp+ecn" ICE
option, as defined by [RFC6064] , then an "rtp+ecn" ICE option MUST
be inserted at the session-level.
7. Security Considerations
This document does not add any security considerations beyond what is
discussed in [RFC5245] .
8. IANA Considerations
No IANA considerations.
9. Acknowledgements
This document was written with the xml2rfc tool described in
[RFC2629] .
10. References
10.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC5245] Rosenberg, J., "Interactive Connectivity Establishment
(ICE): A Protocol for Network Address Translator (NAT)
Traversal for Offer/Answer Protocols", RFC 5245,
April 2010.
[RFC6679] Westerlund, M., Johansson, I., Perkins, C., O'Hanlon, P.,
and K. Carlberg, "Explicit Congestion Notification (ECN)
for RTP over UDP", RFC 6679, August 2012.
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10.2. Informative References
[RFC2629] Rose, M., "Writing I-Ds and RFCs using XML", RFC 2629,
June 1999.
[RFC4566] Handley, M., Jacobson, V., and C. Perkins, "SDP: Session
Description Protocol", RFC 4566, July 2006.
[RFC5159] Dondeti, L. and A. Jerichow, "Session Description Protocol
(SDP) Attributes for Open Mobile Alliance (OMA) Broadcast
(BCAST) Service and Content Protection", RFC 5159,
March 2008.
[RFC5888] Camarillo, G. and H. Schulzrinne, "The Session Description
Protocol (SDP) Grouping Framework", RFC 5888, June 2010.
[RFC6064] Westerlund, M. and P. Frojdh, "SDP and RTSP Extensions
Defined for 3GPP Packet-Switched Streaming Service and
Multimedia Broadcast/Multicast Service", RFC 6064,
January 2011.
[I-D.loreto-splices-disaggregated-media]
Camarillo, G., Loreto, S., and R. Shekh-Yusef,
"Disaggregated Media in the Session Initiation Protocol
(SIP)", draft-loreto-splices-disaggregated-media-02 (work
in progress), June 2011.
URIs
[1] <http://www.rfc-editor.org/errata_search.php?eid=3149>
Appendix A. Examples
A.1. Aggregating media all supporting ICE
In this example, we have two SDP to aggregate. The first SDP
contains an ice-options attribute at the media level:
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v=0
o=jdoe 2890844526 2890842807 IN IP4 10.0.1.1
s=
c=IN IP4 192.0.2.3
t=0 0
a=ice-options:rtp+ecn
a=ice-pwd:asd88fgpdd777uzjYhagZg
a=ice-ufrag:8hhY
m=audio 45664 RTP/AVP 0
b=RS:0
b=RR:0
a=rtpmap:0 PCMU/8000
a=candidate:1 1 UDP 2130706431 10.0.1.1 8998 typ host
a=candidate:2 1 UDP 1694498815 192.0.2.3 45664 typ srflx raddr
10.0.1.1 rport 8998
m=text 45666 RTP/AVP 98
b=RS:0
b=RR:0
a=rtpmap:98 t140/1000
a=candidate:1 1 UDP 2130706431 10.0.1.1 9000 typ host
a=candidate:2 1 UDP 1694498815 192.0.2.3 45666 typ srflx raddr
10.0.1.1 rport 9000
The second SDP also have an ice-options attribute at the media level:
v=0
o=jdoe 1 1 IN IP4 10.0.1.2
s=
c=IN IP4 192.0.2.4
t=0 0
a=ice-options:rtp+ecn
a=ice-pwd:f7sD7f7dF87s87d7da5564
a=ice-ufrag:776G
m=video 10000 RTP/AVP
b=RS:0
b=RR:0
a=rtpmap:0 PCMU/8000
a=candidate:1 1 UDP 2130706431 10.0.1.2 10000 typ host
a=candidate:2 1 UDP 1694498815 192.0.2.4 45000 typ srflx raddr
10.0.1.1 rport 10000
The first step is to copy the session-level ice-options attribute as
media-level attribute. The first SDP is modified like this:
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v=0
o=jdoe 2890844526 2890842807 IN IP4 10.0.1.1
s=
c=IN IP4 192.0.2.3
t=0 0
a=ice-options:rtp+ecn
a=ice-pwd:asd88fgpdd777uzjYhagZg
a=ice-ufrag:8hhY
m=audio 45664 RTP/AVP 0
b=RS:0
b=RR:0
a=rtpmap:0 PCMU/8000
a=ice-options:rtp+ecn
a=candidate:1 1 UDP 2130706431 10.0.1.1 8998 typ host
a=candidate:2 1 UDP 1694498815 192.0.2.3 45664 typ srflx raddr
10.0.1.1 rport 8998
m=text 45666 RTP/AVP 98
b=RS:0
b=RR:0
a=rtpmap:98 t140/1000
a=ice-options:rtp+ecn
a=candidate:1 1 UDP 2130706431 10.0.1.1 9000 typ host
a=candidate:2 1 UDP 1694498815 192.0.2.3 45666 typ srflx raddr
10.0.1.1 rport 9000
The second SDP is modified like this:
v=0
o=jdoe 1 1 IN IP4 10.0.1.2
s=
c=IN IP4 192.0.2.4
t=0 0
a=ice-options:rtp+ecn
a=ice-pwd:f7sD7f7dF87s87d7da5564
a=ice-ufrag:776G
m=video 10000 RTP/AVP
b=RS:0
b=RR:0
a=rtpmap:0 PCMU/8000
a=ice-options:rtp+ecn
a=candidate:1 1 UDP 2130706431 10.0.1.2 10000 typ host
a=candidate:2 1 UDP 1694498815 192.0.2.4 45000 typ srflx raddr
10.0.1.1 rport 10000
After aggregation, all the individual media keep their media-level
ice-options attribute, and a session-level ice-options attribute is
added as per the rule in Section 3 :
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v=0
o=- 1309452627 1309452627 IN IP4 10.0.1.1
s=
t=0 0
a=ice-options:rtp+ecn
m=audio 45664 RTP/AVP 0
c=IN IP4 192.168.2.3
b=RS:0
b=RR:0
a=rtpmap:0 PCMU/8000
a=ice-options:rtp+ecn
a=ice-pwd:asd88fgpdd777uzjYhagZg
a=ice-ufrag:8hhY
a=candidate:1 1 UDP 2130706431 10.0.1.1 8998 typ host
a=candidate:2 1 UDP 1694498815 192.0.2.3 45664 typ srflx raddr
10.0.1.1 rport 8998
m=text 45666 RTP/AVP 98
c=IN IP4 192.168.2.3
b=RS:0
b=RR:0
a=rtpmap:98 t140/1000
a=ice-options:rtp+ecn
a=ice-pwd:asd88fgpdd777uzjYhagZg
a=ice-ufrag:8hhY
a=candidate:1 1 UDP 2130706431 10.0.1.1 9000 typ host
a=candidate:2 1 UDP 1694498815 192.0.2.3 45666 typ srflx raddr
10.0.1.1 rport 9000
m=video 10000 RTP/AVP
c=IN IP4 192.168.2.4
b=RS:0
b=RR:0
a=rtpmap:0 PCMU/8000
a=ice-options:rtp+ecn
a=candidate:1 1 UDP 2130706431 10.0.1.2 10000 typ host
a=candidate:2 1 UDP 1694498815 192.0.2.4 45000 typ srflx raddr
10.0.1.1 rport 10000
A.2. Aggregating media partially supporting ICE
In this example, we have two SDP to aggregate, but the second one
does not use ICE. The first SDP contains an ice-options attribute at
the media level:
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v=0
o=jdoe 2890844526 2890842807 IN IP4 10.0.1.1
s=
c=IN IP4 192.0.2.3
t=0 0
a=ice-options:rtp+ecn
a=ice-pwd:asd88fgpdd777uzjYhagZg
a=ice-ufrag:8hhY
m=audio 45664 RTP/AVP 0
b=RS:0
b=RR:0
a=rtpmap:0 PCMU/8000
a=candidate:1 1 UDP 2130706431 10.0.1.1 8998 typ host
a=candidate:2 1 UDP 1694498815 192.0.2.3 45664 typ srflx raddr
10.0.1.1 rport 8998
m=text 45666 RTP/AVP 98
b=RS:0
b=RR:0
a=rtpmap:98 t140/1000
a=candidate:1 1 UDP 2130706431 10.0.1.1 9000 typ host
a=candidate:2 1 UDP 1694498815 192.0.2.3 45666 typ srflx raddr
10.0.1.1 rport 9000
The second SDP does not contain any ice-options attribute:
v=0
o=jdoe 1 1 IN IP4 10.0.1.2
s=
c=IN IP4 192.0.2.4
t=0 0
m=video 10000 RTP/AVP
a=rtpmap:0 PCMU/8000
The first step is to copy the session-level ice-options attribute as
media-level attribute. Only the first SDP is modified in this
example:
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v=0
o=jdoe 2890844526 2890842807 IN IP4 10.0.1.1
s=
c=IN IP4 192.0.2.3
t=0 0
a=ice-options:rtp+ecn
a=ice-pwd:asd88fgpdd777uzjYhagZg
a=ice-ufrag:8hhY
m=audio 45664 RTP/AVP 0
b=RS:0
b=RR:0
a=rtpmap:0 PCMU/8000
a=ice-options:rtp+ecn
a=candidate:1 1 UDP 2130706431 10.0.1.1 8998 typ host
a=candidate:2 1 UDP 1694498815 192.0.2.3 45664 typ srflx raddr
10.0.1.1 rport 8998
m=text 45666 RTP/AVP 98
b=RS:0
b=RR:0
a=rtpmap:98 t140/1000
a=ice-options:rtp+ecn
a=candidate:1 1 UDP 2130706431 10.0.1.1 9000 typ host
a=candidate:2 1 UDP 1694498815 192.0.2.3 45666 typ srflx raddr
10.0.1.1 rport 9000
After aggregation, all the individual media keep their media-level
ice-options attribute, and a session-level ice-options attribute is
added as per the rule in Section 3 :
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v=0
o=- 1309452627 1309452627 IN IP4 10.0.1.1
s=
t=0 0
a=ice-options:rtp+ecn
m=audio 45664 RTP/AVP 0
c=IN IP4 192.168.2.3
b=RS:0
b=RR:0
a=rtpmap:0 PCMU/8000
a=ice-options:rtp+ecn
a=ice-pwd:asd88fgpdd777uzjYhagZg
a=ice-ufrag:8hhY
a=candidate:1 1 UDP 2130706431 10.0.1.1 8998 typ host
a=candidate:2 1 UDP 1694498815 192.0.2.3 45664 typ srflx raddr
10.0.1.1 rport 8998
m=text 45666 RTP/AVP 98
c=IN IP4 192.168.2.3
b=RS:0
b=RR:0
a=rtpmap:98 t140/1000
a=ice-options:rtp+ecn
a=ice-pwd:asd88fgpdd777uzjYhagZg
a=ice-ufrag:8hhY
a=candidate:1 1 UDP 2130706431 10.0.1.1 9000 typ host
a=candidate:2 1 UDP 1694498815 192.0.2.3 45666 typ srflx raddr
10.0.1.1 rport 9000
m=video 10000 RTP/AVP
c=IN IP4 192.168.2.4
a=rtpmap:0 PCMU/8000
Appendix B. Analysis of similar issues in other attributes
In the MMUSIC WG session in Quebec City, it was suggested that the
problem was perhaps larger than just ICE attributes. This section is
the result of a systematic look at all the session level only SDP
attributes registered by IANA at the date of this document. The
conclusion is that only the ICE attributes are of concern but that
steps should be taken to ensure that these problems cannot happen for
future new attributes.
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+--------------------+----------------------------+--------------+
| Attribute | Reference | Comments |
+--------------------+----------------------------+--------------+
| cat | [RFC4566] | OK |
| keywds | [RFC4566] | OK |
| type | [RFC4566] | OK |
| type:broadcast | [RFC4566] | Appendix B.1 |
| type:H332 | [ITU Recommendation H.332] | OK |
| type:meeting | [RFC4566] | OK |
| type:moderated | [RFC4566] | OK |
| type:test | [RFC4566] | OK |
| charset | [RFC4566] | Appendix B.2 |
| charset:iso8895-1 | [RFC4566] | Appendix B.2 |
| tool | [RFC4566] | Appendix B.3 |
| ipbcp | [ITU-T Q.1970] | Appendix B.4 |
| group | [RFC5888] | OK |
| ice-lite | [RFC5245] | Section 4 |
| ice-mismatch | [RFC5245] | Section 5 |
| ice-options | [RFC5245] | Section 3 |
| bcastversion | [RFC5159] | Appendix B.4 |
| 3GPP-Integrity-Key | [RFC6064] | Appendix B.4 |
| 3GPP-SDP-Auth | [RFC6064] | Appendix B.4 |
| alt-group | [RFC6064] | Appendix B.4 |
| PSCid | [TS 183 063] | Appendix B.4 |
| bc_service | [TS 183 063] | Appendix B.4 |
| bc_program | [TS 183 063] | Appendix B.4 |
| bc_service_package | [TS 183 063] | Appendix B.4 |
+--------------------+----------------------------+--------------+
B.1. The type:broadcast Attribute
The "type:broadcast" does not have any issue by itself, but it should
be noted that it implies a default attribute of recvonly, so the
disaggregation process must take this in account.
B.2. The charset Attribute
Because the main reason to use a different charset for a session
description is to generate a more compact representation, it is
probably OK that this attribute exists only at the session level.
But the aggregation/disaggregation rules must explicitly convert the
individual media descriptions to and from the common charset, ISO-
10646.
B.3. The tool Attribute
The definition of this attribute make it clear that this attribute
contains the name and version number of the tool that created the
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session description as a whole. But it probably would be useful to
define this attribute at the media level too, so we can know the
tools used for create the individual media descriptions.
B.4. The ipbcp, bcastversion, 3GPP-Integrity-Key, 3GPP-SDP-Auth, alt-
group, PSCid, bc_service, bc_program and bc_service_package
Attributes
These attributes were not defined in IETF Standard Track documents,
so the analysis is left to the SDOs that produced this
specifications.
Appendix C. Release notes
This section must be removed before publication as an RFC.
C.1. Modifications between -04 and -03
o Updated rtp+ecn reference.
o IANA registry for ice-mismatch fixed.
C.2. Design Notes
o It has been proposed multiple times to use a different attribute
name for the ice-options attribute when used at the media-level.
Using a different name does not solve the aggregation problem and,
in the opinion of this author, could create confusion.
Author's Address
Marc Petit-Huguenin
Impedance Mismatch
Email: petithug@acm.org
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