Hello all,
I have a question regarding retransmission of 200OK.
Proxy can send 100 Trying to stop retransmission on invites on UAC
is there any way to control retransmission of 200OK from UAS?
Is this a valid senario? Will PRACK stop retransmission of 200Ok messages?
UAC ---------------Proxy --------------------------UAS
--------Invite--------------------------------------------->
<------------------------------100 trying-----------------
<--------------------------------180 ringing--------------
<--------------------------------200 Ok---------------------
------------PRACK---------------->
<-------------200 OK (prack------
-----------------------------------ACK-------------------->
<-------------------------------rtp--------------------------->
RFC 3262
The reliability mechanism works by mirroring the current reliability
mechanisms for 2xx final responses to INVITE. Those requests are
transmitted periodically by the Transaction User (TU) until a
separate transaction, ACK, is received that indicates reception of
the 2xx by the UAC. The reliability for the 2xx responses to INVITE
and ACK messages are end-to-end. In order to achieve reliability for
provisional responses, we do nearly the same thing. Reliable
provisional responses are retransmitted by the TU with an exponential
backoff. Those retransmissions cease when a PRACK message is
received. The PRACK request plays the same role as ACK, but for
provisional responses. There is an important difference, however.
PRACK is a normal SIP message, like BYE. As such, its own
reliability is ensured hop-by-hop through each stateful proxy. Also
like BYE, but unlike ACK, PRACK has its own response. If this were
not the case, the PRACK message could not traverse proxy servers
compliant to RFC 2543 [4]Any help is appreciated.
Thanks
Sid
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