Baniel Uri-CUB001 wrote:
The ACK will not have a To-Tag, since proxies do not end To-tags to
their responses (e.g. the 4xx you mentioned), but only the end points
add them,
Not quite; a proxy is actually quite free to add tags in the
responses it generates (see rfc3261, section 16.7, step 6 --
towards the beginning of page 112). The only stipulations are
that a proxy must not change tags if a response it is proxying
already has tags; and it must, of course, not add tags to a
response that it is proxying which does not have any tags.
thus the proxy will notice there is no To-tag in the ACK, and should
realize this one is to be consumed by itself.
rfc3261 actually made it easier to match ACKs to pending INVITE
transactions for non-2xx responses -- see Section 8.1.1.7, third
paragraph. All you need to match an ACK for a non-2xx response
is the branch ID of the topmost Via.
- vijay
--
Vijay K. Gurbani [EMAIL PROTECTED],research.bell-labs.com,acm.org}
Wireless Networks Group/Internet Software and Services
Lucent Technologies/Bell Labs Innovations, 2000 Lucent Lane, Rm 6G-440
Naperville, Illinois 60566 Voice: +1 630 224 0216
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