INtermediary-safe SIP session ID (insipid)

Charter for Working Group

An end-to-end session identifier in SIP-based multimedia
communication networks refers to the ability for endpoints,
intermediate devices, and management and monitoring system to
identify and correlate SIP messages and dialogs of the same
higher-level end-to-end "communication session" across multiple
SIP devices, hops, and administrative domains. Unfortunately,
there are a number of factors that contribute to the fact that
the current dialog identifiers defined in SIP are not suitable
for end-to-end session identification. Perhaps the most important
factor worth describing is that in real-world deployments of
Back-to-Back User Agents (B2BUAs) devices like Session Border
Controllers (SBC) often change the call identifiers (e.g., the
From-tag and To-tag that are used in conjunction with the Call-ID
header to make the dialog-id) as the session signaling passes
through.

An end-to-end session identifier should allow the possibility to
identify the communication session from the point of origin,
passing through any number of intermediaries, to the ultimate
point of termination. It should have the same aim as the
From-tag, To-tag and Call-ID conjunction, but should not be
mangled by intermediaries.

A SIP end-to-end session identifier has been considered as possible
solution of different use cases like troubleshooting, billing, session
tracking, session recording, media and signaling correlation, and so
forth. Some of these requirements come from other working groups
within the RAI area (e.g., SIPRec). Moreover, other standards
organizations have identified the need for SIP and H.323 to carry the
same "session ID" value so that it is possible to identify a call
end-to end even when performing inter working between protocols.

This group will focus on a document that will specify a SIP
identifier that has the same aim as the From-tag, To-tag and Call-ID
conjunction, but is less likely to be mangled by intermediaries. In
doing this work, the group will pay attention to the privacy
implications of a "session ID", for example considering the
possibility to make it intractable for nodes to correlate "session IDs"
generated by the same user for different sessions.

Milestones