Internet Engineering Task Force Sean Olson
Internet draft Adam Roach
Gonzalo Camarillo
Ericsson
December 2001
Expires May 2002
<draft-olson-sdp-ipv6-03.txt>
Support for IPv6 in SDP
Status of this Memo
This document is an Internet-Draft and is in full conformance with
all provisions of Section 10 of RFC2026.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that
other groups may also distribute working documents as Internet-
Drafts. Internet-Drafts are draft documents valid for a maximum of
six months and may be updated, replaced, or obsoleted by other
documents at any time. It is inappropriate to use Internet- Drafts
as reference material or to cite them other than as "work in
progress."
The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt
The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html.
Abstract
This document describes the use of IPv6 addresses [1] in conjunction
with the Session Description Protocol (SDP) [2]. Specifically, this
document clarifies existing text in SDP with regards to the syntax of
IPv6 addresses.
1. Introduction
SDP is intended for describing multimedia sessions for the purposes of
session announcement, session invitation, and other forms of multimedia
session initiation. It is a text format description that provides
many details of a multimedia session including: the originator of the
session, a URL related to the session, the connection address for the
session media(s), and optional attributes for the session media(s).
Each of these pieces of information may involve one or more IPv6
addresses. The ABNF for IP addresses in SDP currently leaves the syntax
for IPv6 addresses undefined. This Internet-Draft attempts to complete
the ABNF to include IPv6 addresses.
Accordingly, the address type "IP6" indicating an IPv6 address, should
be allowed in the connection field, "c=", of the SDP. The ABNF already
reflects this, though the "Connection Data" text under section 6 of
RFC2328 currently only defines the "IP4" address type.
Olson, et. al. [Page 1]
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
RFC 2119.
3. Syntax
RFC2373 [1] gives an ABNF for the text representation of IPv6 addresses in
Appendix B. RFC2732 [3] covers the text representation of IPv6 addresses
when used within a URL. Using the ABNF described in these documents, the
following updated ABNF for SDP is proposed.
uri = ; defined in RFC1630 and RFC2732
multicast-address = IP4-multicast | IP6-multicast
IP4-multicast = m1 3*( "." decimal-uchar ) "/" ttl [ "/" integer ]
; IPv4 multicast addresses may be in the range
; 224.0.0.0 to 239.255.255.255
m1 = ("22" ("4"|"5"|"6"|"7"|"8"|"9")) | ("23" DIGIT ))
IP6-multicast = hexpart [ ":" IP4-multicast ]
"/" ttl [ "/" integer ]
; IPv6 address starting with FF00
addr = FQDN | unicast-address
FQDN = 4*(alpha-numeric|"-"|".")
; fully qualified domain name as specified in
; RFC1035
unicast-address = IP4-address | IP6-address
IP4-address = b1 "." decimal-uchar "." decimal-uchar "." b4
| "0.0.0.0"
b1 = decimal-uchar
; less than "224"; not "0" or "127"
b4 = decimal-uchar
; not "0"
IP6-address = *( HEXDIGIT | "." | ":" )
; As defined in the IPv6 addressing architecture
Olson, et. al. [Page 2]
4. Additional IPv6 Issues in SDP
4.1 IPv6 Addresses with Embedded IPv4 Addresses
RFC2373 defines two ways in which an IPv4 address may be
encoded in an IPv6 address. In both forms, the lower 32 bits
of the IPv6 address contain the IPv4 address. The first form is an
"IPv4 compatible IPv6 address" and it has the format:
| 80 bits | 16 | 32 bits |
+--------------------------------------+--------------------------+
|0000..............................0000|0000| IPv4 address |
+--------------------------------------+----+---------------------+
The second form of address is used to represent the addresses of
IPv4-only nodes (those that *do not* support IPv6) as IPv6 addresses.
This type of address is termed an "IPv4-mapped IPv6 address" and has
the format:
| 80 bits | 16 | 32 bits |
+--------------------------------------+--------------------------+
|0000..............................0000|FFFF| IPv4 address |
+--------------------------------------+----+---------------------+
The difference in format is significant and MAY be treated
differently in SDP implementations.
5. Example SDP description with IPv6 addresses
The following is an example SDP description using the above ABNF
for IPv6 addresses. In particular, the origin, URI, and connection
fields contain IPv6 addresses. The URI contains an IPv4 compatible
IPv6 address.
v=0
o=nasa1 971731711378798081 0 IN IP6 2201:056D::112E:144A:1E24
s=(Almost) live video feed from Mars-II sattelite
u=http://[::FFFF:10.2.12.126]/marsII
p=+1 713 555 1234
c=IN IP6 FF00:03AD::7F2E:172A:1E24
t=3338481189 3370017201
m=audio 6000 RTP/AVP 2
a=rtpmap:2 G726-32/8000
m=video 6024 RTP/AVP 107
a=rtpmap:107 H263-1998/90000
6. Backward compatibility
An implementation that does not understand or wish to accept
the IPv6 extensions to the SDP grammar MUST reject the SDP.
7. IANA Considerations
This document updates the definition of the IP6 addrtype parameter
found in RFC2327.
8. Security Considerations
No additional considerations above what is stated in section 7 of
RFC2327.
Olson, et. al. [Page 3]
9. References
[1] R. Hinden and S. Deering, "IP Version 6 Addressing Architecture",
RFC2373, IETF.
[2] M. Handley and V. Jacobson, "Session Description Protocol",
RFC2327, IETF.
[3] R. Hinden, et. al., "Format for Literal IPv6 Addresses in URL's",
RFC2732, IETF.
[4] D. Crocker and P. Overell,
"Augmented BNF for Syntax Specifications: ABNF",
RFC2234, IETF.
[5] S. Bradner, "Key words for use in RFCs to Indicate Requirement
Levels", RFC2119, IETF.
10. Author's Addresses
Sean Olson
Richardson, Texas
USA
Email: seancolson AT yahoo.com
Gonzalo Camarillo
Ericsson
Advanced Signalling Research Lab.
FIN-02420 Jorvas
Finland
Phone: +358 9 299 3371
Fax: +358 9 299 3118
Email: Gonzalo.Camarillo@ericsson.com
Adam Roach
Ericsson
Richardson, Texas
USA
Phone: +1 972 583 7594
Fax: +1 972 669 0154
Email: Adam.Roach@ericsson.com
Olson, et. al. [Page 4]