Internet Engineering Task Force SIP WG Internet Draft Oran/Schulzrinne draft-oran-sip-visited-00.txt Cisco/Columbia U. August 6, 2000 Expires: December 2000 SIP extension for tracking locations attempted 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 To view the list Internet-Draft Shadow Directories, see http://www.ietf.org/shadow.html. Abstract Proxying hides the destinations tried by the proxy. Since this information is sometimes useful to the requestor, this draft proposes a new optional SIP request header called Contacts-Tried listing the locations tried unsuccessfully during a search. 1 Introduction It may be useful for the initiator of a request to track which locations have been tried while forking calls, particularly if recursive indirection is involved. For example, this allows a caller to avoid manually calling a person that has already been tried as part of proxy forking. 2 Syntax Oran/Schulzrinne [Page 1]
Internet Draft SIP August 6, 2000 Contacts-Tried = "Contacts-Tried" ":" # ( name-addr | addr-spec *(";" ct-params ) ct-params = "reason" = quoted-string | "status" = Status-Code The "reason" parameter contains the reason phrase from the response, while the "status" parameter identifies the numeric status code. The "reason" parameter MAY be present if and only if the "status" parameter is present. The order of elements has no significance. Each proxy adds to the list in responses returned from downstream servers. Example: Contacts-Tried: "A. G. Bell" <a.g.bell@bell-tel.com> ;reason="Busy" ;status=600, "T. Bell" <t.bell@bell-tel.com> ;reason="I don't talk to telemarketers" ;status=603 3 Security Considerations Users may expect proxying and forwarding information to remain private. Thus, proxies MUST NOT reveal this information by default and MUST only reveal this information only if the party designated in the To header field has agreed to have this information revealed. 4 Authors' Addresses David R. Oran Cisco Systems 7 Ladyslipper Lane Acton, MA 01720 USA Email: oran@cisco.com Henning Schulzrinne Dept. of Computer Science Columbia University 1214 Amsterdam Avenue New York, NY 10027 USA Email: schulzrinne@cs.columbia.edu Oran/Schulzrinne [Page 2]