Technical Summary
This specification defines a new Session Initiation Protocol (SIP) Via
header field parameter, "received-realm", which allows a SIP entity acting
as an entry point to a transit network to indicate from which adjacent
upstream network a SIP request is received, using a network realm value
associated with the adjacent network. This is needed in some network
architectures to determine what processing should be applied to the request.
Working Group Summary
This document was brought to the DISPATCH working group in June of 2015.
Several WG participants expressed interest in seeing the work progress to
publication, and a follow-up conversation was held at IETF 93 to determine
how the work should proceed. The outcome of those conversations was that
the mechanism being described was not in the charter of any existing working
group, nor was it of broad enough applicability to warrant creating a new
working group. The DISPATCH working group chose to dispatch this as
sponsored by the area director.
Document Quality
This mechanism was introduced to address use cases identified by 3GPP for
transit networks providing telecom-style services to SIP calls in an IMS
context. The mechanism has been cited by 3GPP's TS 24.229 and incorporated as
part of its procedures since March 2015. This presumably will lead to broad
implementation of the mechanism by IMS equipment vendors.
The original mechanism did not contain any authentication for information that
was subsequently used for service processing. In response to security
concerns, raised by Adam Roach and Richard Barnes, the mechanism was expanded
to incorporate a JWS-based authentication of the realm being asserted.
Personnel
Adam Roach is the document shepherd. Ben Campbell is the area director
sponsoring publication.