Internet Engineering Task Force                                MMUSIC WG
Internet Draft                                            H. Schulzrinne
ietf-mmusic-sip-url-00.txt                                   Columbia U.
May 14, 1997
Expires: November 1, 1997

                             SIP URL Scheme


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         A family of new URL schemes, "sip*:", is defined. It is
         used to establish multimedia conferences using the
         Session Initiation Protocol (SIP).

1 URL Syntax

   This URL does not designate a data object, but rather requests the
   initiation of a conference with the designated party using the
   Session Initation Protocol (SIP) [1]. The details of this conference,
   such as the type and parameters of media to be used, are not
   specified by this URL but may be negotiated by the protocol itself.

   A SIP URL is based on the Common Internet Scheme Syntax described in
   section 3.1 of RFC 1738 [2]. It has the general forms:

H. Schulzrinne                                                [Page 1]

Internet Draft                    sip                       May 14, 1997


   The " :<password> ", " ,<ttl> ", " :<port> " parts are optional. If
   the port is omitted, then port TBD is assumed for schemes sip:  ,
   sipu:  , and sipt:  and port TBD for scheme sips:

   The URL scheme name also designates the transport protocol to be used
   by SIP. For sip:  , either UDP or TCP may be used, depending on the
   preference of the entity resolving the URL. sipu:  and sipt:
   explicitly request use of UDP and TCP. sips:  requests use of SSL
   over TCP.

   The ttl value designates the multicast time-to-live value. This field
   MUST NOT be used if the host part of the URL is a unicast address.
   The default value is one. The ttl value is mandatory if the host
   address designates an IPv6 multicast address. (The textual
   representation of IPv6 addresses contain colons and thus cannot be
   delineated from the port identifier.)


   The following BNF includes the generic definitions of RFC 1738,
   Section 5.

   sip_URL        = ( "sip:" | "sips:" | "sipt:" | "sipu:" ) "//" login
   login          = [ user [ ":" password ] "@" ] host_ttl_port
   host_ttl_port  = host [ "," ttl ] [ ":" port ]
   ttl            = digits

3 Author's Address

   Henning Schulzrinne
   Dept. of Computer Science
   Columbia University
   1214 Amsterdam Avenue
   New York, MY 10027
   electronic mail:

4 Bibliography

H. Schulzrinne                                                [Page 2]

Internet Draft                    sip                       May 14, 1997

   [1] M. Handley, H. Schulzrinne, and E. Schooler, "SIP: session
   initiation protocol," Internet Draft, Internet Engineering Task
   Force, Mar. 1997.  Work in progress.

   [2] T. Berners-Lee, L. Masinter, and M. McCahill, "Uniform resource
   locators (URL),"  RFC 1738, Internet Engineering Task Force, Dec.

H. Schulzrinne                                                [Page 3]