Internet Engineering Task Force                 Sean Olson
 Internet draft                                  Adam Roach
                                                 Gonzalo Camarillo
                                                 Ericsson
                                                 January 2002
                                                 Expires July 2002
                                   <draft-ietf-mmusic-sdp-ipv6-00.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]