JUNHYUK SONG INTERNET DRAFT SAMSUNG ELECTRONICS April 2003 SIP server [-IPCP-] configuration option for PPP [-draft-song-pppext-sip-support-01.txt-] {+draft-song-pppext-sip-support-02.txt+} Status of This Memo Distribution of this memo is unlimited. 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 defines a new configuration option for the PPP IPCP (PPP Internet Protocol Control Protocol), to return a list of the IPv4 addresses of SIP proxy servers. This option provides one mechanism that a system may use to locate a SIP proxy server. This approach is applicable for a system that is using PPP for the link layer protocol and IP address allocation. Song Expires October 2003 [Page 1] Internet Draft April 2003 1. Introduction The SIP (Session Initiation Protocol)[3] is a signaling protocol used for the session invitation, [-modification-] {+modification,+} and termination. The [-UAC(User-] {+UAC (User+} Agent Client) sends a request to the [-UAS(User-] {+UAS (User+} Agent Server). However, the request message (INVITE) is not directly sent to the callee UAS, it rather [-go-] {+goes+} through proxy [-servers,-] {+servers+} and possibly redirect servers. This draft [-is specifying-] {+specifyies+} one mechansim that a system may use to locate a SIP [-procy-] {+proxy+} server. This draft [-is specifying a-] {+specifies an+} IPCP {+(PPP Internet Protocol Control Protocol)+} option that allows SIP clients to locate a list of SIP proxy servers that is to be used for all SIP requests. This approach is applicable to [-the-] {+a+} system utilizing PPP for [-the-] {+its+} link layer protocol and IP address allocation (ex. 3GPP2 Packet Data System) [-Note :-] {+Note: the text defining+} the format and behavior of these options [-are-] {+is+} quoted from RFC1877 [-[2] for the sake of-] {+[2], to ensure a+} consistent [-implementation of PPP.-] {+implementation.+} 2. Configuration Options The {+IPCP+} Configuration Option format and {+the+} basic options are defined [-by IPCP configuration option-] {+in RFC 1332+} [4]. This document [-concerns-] {+defines+} the [-following values: [?]-] {+two new options:+} Primary SIP Server Address [-[?+1]-] {+and+} Secondary SIP Server [-Address-] {+Address.+} 2.1. Primary SIP [-server-] {+Server+} Address Option Description This Configuration Option [-defines a method-] {+is used+} for negotiating with the remote peer the address of the primary SIP server Address to be used on the local end of the link. [-By default, no primary SIP server address is provided.-] A summary of the Primary SIP Address Configuration Option format is shown below. The fields are transmitted from left to right. Song Expires October 2003 [Page 2] Internet Draft April 2003 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type | Length | Primary-SIP-Server Address +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Primary-SIP-Server Address(cont)| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Type ? [-(Primary-] {+[To be assigned by IANA] Primary+} SIP [-Proxy server)-] {+Server Address Option+} Length 6 [-Primary-SIP-Address-] {+Primary-SIP-Server-Address+} The four octet Primary-SIP-Server Address is the address of the primary proxy SIP server to be used by the local peer. [-If all-] {+Setting these+} four octets [-are set-] to [-zero, it indicates an explicit request-] {+zero requests+} that the peer provide the address information in a Config-Nak packet. Default No {+primary server+} address is provided. 1.3. Secondary SIP Server Address {+Option+} Description This Configuration Option [-defines a method-] {+is used+} for negotiating with the remote peer the address of the secondary SIP server Address to be used on the local end of the link. [-By default, no secondary SIP address is provided.-] Song Expires October 2003 [Page 3] Internet Draft April 2003 A summary of the Secondary SIP Address Configuration Option format is shown below. The fields are transmitted from left to right. 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type | Length |Secondary-SIP-Server Address +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Secondary-SIP-Server Addr (cont)| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Type ?+1 [-(Secondary-] {+[To be assigned by IANA] Secondary+} SIP [-Proxy server)-] {+Server Address Option+} Length 6 [-Secondary-SIP-Address-] {+Secondary-SIP-Server-Address+} The four octet Secondary-SIP-Server Address is the address of the secondary SIP server to be used by the local peer. [-If all-] {+Setting+} four octets are set to [-zero, it indicates an explicit request-] {+zero requests+} that the peer provide the address information in a Config-Nak packet. Default [-No-] {+By default, no secondary SIP+} address is provided. 3. IANA Considerations Requires IPCP option number assignment 4. Acknowledgements A major portion of the text in this memo was quoted from RFC 1877. Song Expires October 2003 [Page 4] Internet Draft April 2003 References [1] Simpson, W., Editor, "The Point-to-Point Protocol (PPP)", STD 51, RFC 1661, Daydreamer, July 1994. [2] Steve Cobb, "PPP Internet Protocol Control Protocol Extensions for Name Server Addresses" RFC 1877, Microsoft, [3] M. Handley, H. Schulzrinne, E. Schooler, and J. Rosenberg, "SIP: session initiation protocol," Request for Comments 2543, Internet Engineering Task Force, Mar. 1999. [4] McGregor, G., "PPP Internet Control Protocol", RFC 1332, Merit, May 1992. Addresses Questions about this memo can be directed to the authors: JUNHYUK SONG SAMSUNG ELECTRONICS. Packet Technology System Lab. Mobile Development Team Phone: +82-31-279-3639 Email: junhyuk@telecom.samsung.co.kr santajunman@yahoo.com Song Expires October 2003 [Page 5] Internet Draft April 2003 Full Copyright Statement Copyright (C) The Internet Society (2003). 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