hi,
as we know that
Via is always used to forward responses.
Route is always used to determine where to forward
requests
Also let us consider a typical call flow..assume two
intermediate proxies..( A-->p1-->p2-->B)
INVITE -- RecordRoute: p2,p1
200 (invite) -- RecordRoute: p2,p1
ACK -- Route : p2,b
BYE -- Route : p1,b
200 (bye)
---------------------------------------------
Now my query is what is the need for the Via: list
being built up for ACK as it traverses from
(A-->p1-->p2-->B)as Via: is used by responses to trace
back the path, but ACK does not generate any
responses.
Now then if the Via: in ACK is built to help for
building Route: for a BYE request from
(B-->p2-->p1-->A), then i would argue that
B(callee/server) already knows the route which was
relayed in the INVITE (record-route) built-up while
traversing through the proxies and it was B which
intimates A about the Route to be taken for the
subsequent request.
In a Nut-shell is it fair to say that the Route for
subsequent transaction is known to both client and
server upon the receiving of a 200 from B-->A. (when B
relays it through the record-route).
Rama
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