;ISO 8859-1 requires "a=charset:ISO-8859-1"
;session-level attribute to be used
byte-string = 1*(%x01-09/%x0B-0C/%x0E-FF)
;any byte except NUL, CR, or LF
non-ws-string = 1*(VCHAR/%x80-FF)
;string of visible characters
token-char = %x21 / %x23-27 / %x2A-2B / %x2D-2E / %x30-39
/ %x41-5A / %x5E-7E
token = 1*(token-char)
email-safe = %x01-09/%x0B-0C/%x0E-27/%x2A-3B/%x3D/%x3F-FF
;any byte except NUL, CR, LF, or the quoting
;characters ()<>
integer = POS-DIGIT *DIGIT
; generic sub-rules: primitives
alpha-numeric = ALPHA / DIGIT
POS-DIGIT = %x31-39 ; 1 - 9
decimal-uchar = DIGIT
/ POS-DIGIT DIGIT
/ ("1" 2*(DIGIT))
/ ("2" ("0"/"1"/"2"/"3"/"4") DIGIT)
/ ("2" "5" ("0"/"1"/"2"/"3"/"4"/"5"))
; external references:
; ALPHA, DIGIT, CRLF, SP, VCHAR: from RFC 4234
; URI-reference: from RFC 3986
; addr-spec: from RFC 2822
10. Summary of Changes from RFC 2327
The memo has been significantly restructured, incorporating a large
number of clarifications to the specification in light of use. With
the exception of those items noted below, the changes to the memo are
intended to be backward-compatible clarifications. However, due to
inconsistencies and unclear definitions in RFC 2327 it is likely that
some implementations interpreted that memo in ways that differ from
this version of SDP.
The ABNF grammar in Section 9 has been extensively revised and
updated, correcting a number of mistakes and incorporating the RFC
3266 IPv6 extensions. Known inconsistencies between the grammar and
the specification text have been resolved.
A media type registration for SDP is included. Requirements for the
registration of attributes and other parameters with IANA have been
clarified and tightened (Section 8). It is noted that "text" and
"message" are valid media types for use with SDP, but that "control"
and "data" are under-specified and deprecated.
RFC 2119 terms are now used throughout to specify requirements
levels. Certain of those requirements, in particular in relation to
parameter registration, are stricter than those in RFC 2327.
The "RTP/SAVP" RTP profile and its "fmt" namespace are registered.
The attributes "a=inactive" and "a=maxptime" have been added.
RFC 2327 mandated that either "e=" or "p=" was required. Both are
now optional, to reflect actual usage.
The significant limitations of the "k=" field are noted, and its use
is deprecated.
Most uses of the "x-" prefix notation for experimental parameters are
disallowed and the other uses are deprecated.
11. Acknowledgements
Many people in the IETF Multiparty Multimedia Session Control
(MMUSIC) working group have made comments and suggestions
contributing to this document. In particular, we would like to thank
Eve Schooler, Steve Casner, Bill Fenner, Allison Mankin, Ross
Finlayson, Peter Parnes, Joerg Ott, Carsten Bormann, Steve Hanna,
Jonathan Lennox, Keith Drage, Sean Olson, Bernie Hoeneisen, Jonathan
Rosenberg, John Elwell, Flemming Andreasen, Jon Peterson, and Spencer
Dawkins.
12. References
12.1. Normative References
[1] Mockapetris, P., "Domain names - concepts and facilities", STD
13, RFC 1034, November 1987.
[2] Mockapetris, P., "Domain names - implementation and
specification", STD 13, RFC 1035, November 1987.
[3] Bradner, S., "Key words for use in RFCs to Indicate Requirement
Levels", BCP 14, RFC 2119, March 1997.
[4] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax
Specifications: ABNF", RFC 4234, October 2005.
[5] Yergeau, F., "UTF-8, a transformation format of ISO 10646", STD
63, RFC 3629, November 2003.
[6] Handley, M. and V. Jacobson, "SDP: Session Description
Protocol", RFC 2327, April 1998.
[7] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
Resource Identifier (URI): Generic Syntax", STD 66, RFC 3986,
January 2005.
[8] Narten, T. and H. Alvestrand, "Guidelines for Writing an IANA
Considerations Section in RFCs", BCP 26, RFC 2434, October
1998.
[9] Alvestrand, H., "Tags for the Identification of Languages", BCP
47, RFC 3066, January 2001.
[10] Olson, S., Camarillo, G., and A. Roach, "Support for IPv6 in
Session Description Protocol (SDP)", RFC 3266, June 2002.
[11] Faltstrom, P., Hoffman, P., and A. Costello,
"Internationalizing Domain Names in Applications (IDNA)", RFC
3490, March 2003.
[12] Josefsson, S., "The Base16, Base32, and Base64 Data Encodings",
RFC 3548, July 2003.
12.2. Informative References
[13] Mills, D., "Network Time Protocol (Version 3) Specification,
Implementation", RFC 1305, March 1992.
[14] Handley, M., Perkins, C., and E. Whelan, "Session Announcement
Protocol", RFC 2974, October 2000.
[15] 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.
[16] Schulzrinne, H., Rao, A., and R. Lanphier, "Real Time Streaming
Protocol (RTSP)", RFC 2326, April 1998.
[17] Rosenberg, J. and H. Schulzrinne, "An Offer/Answer Model with
Session Description Protocol (SDP)", RFC 3264, June 2002.
[18] Camarillo, G., Eriksson, G., Holler, J., and H. Schulzrinne,
"Grouping of Media Lines in the Session Description Protocol
(SDP)", RFC 3388, December 2002.
[19] Schulzrinne, H., Casner, S., Frederick, R., and V. Jacobson,
"RTP: A Transport Protocol for Real-Time Applications", STD 64,
RFC 3550, July 2003.
[20] Schulzrinne, H. and S. Casner, "RTP Profile for Audio and Video
Conferences with Minimal Control", STD 65, RFC 3551, July 2003.
[21] Casner, S., "Session Description Protocol (SDP) Bandwidth
Modifiers for RTP Control Protocol (RTCP) Bandwidth", RFC 3556,
July 2003.
[22] Huitema, C., "Real Time Control Protocol (RTCP) attribute in
Session Description Protocol (SDP)", RFC 3605, October 2003.
[23] Baugher, M., McGrew, D., Naslund, M., Carrara, E., and K.
Norrman, "The Secure Real-time Transport Protocol (SRTP)", RFC
3711, March 2004.
[24] Rosenberg, J., Schulzrinne, H., and P. Kyzivat, "Indicating
User Agent Capabilities in the Session Initiation Protocol
(SIP)", RFC 3840, August 2004.
[25] Westerlund, M., "A Transport Independent Bandwidth Modifier for
the Session Description Protocol (SDP)", RFC 3890, September
2004.
[26] International Telecommunication Union, "H.323 extended for
loosely coupled conferences", ITU Recommendation H.332,
September 1998.
[27] Arkko, J., Carrara, E., Lindholm, F., Naslund, M., and K.
Norrman, "Key Management Extensions for Session Description
Protocol (SDP) and Real Time Streaming Protocol (RTSP)", RFC
4567, July 2006.
[28] Andreasen, F., Baugher, M., and D. Wing, "Session Description
Protocol (SDP) Security Descriptions for Media Streams", RFC
4568, July 2006.
[29] Resnick, P., "Internet Message Format", RFC 2822, April 2001.
[30] Hinden, R. and S. Deering, "IP Version 6 Addressing
Architecture", RFC 2373, July 1998.
[31] Freed, N. and J. Klensin, "Media Type Specifications and
Registration Procedures", BCP 13, RFC 4288, December 2005.
Authors’ Addresses
Mark Handley
University College London
Department of Computer Science
Gower Street
London WC1E 6BT
UK
EMail: M.Handley@cs.ucl.ac.uk
Van Jacobson
Packet Design
2465 Latham Street
Mountain View, CA 94040
USA
EMail: van@packetdesign.com
Colin Perkins
University of Glasgow
Department of Computing Science
17 Lilybank Gardens
Glasgow G12 8QQ
UK
EMail: csp@csperkins.org
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