Thangarajan,
The Cisco AS5350 sends the same SDP in the 183 and in the 200. The actual offer is in the 200 as this is transmitted reliably. The original question was if there is any issue with sending the same SDP in a non-reliable 183.
IF the offer had been in the INVITE, RFC3261 allows the same SDP (answer) to be sent in a 1xx and in the 200 (it MUST be in the 200). There is no corresponding text for SDP in 1xx when the offer is not in the INVITE. However it is not explicitly forbidden.
Section 13.2.1 of RFC3261 also says, "The initial offer MUST be in either an INVITE or, if not there, in the first reliable non-failure message from the UAS back to the UAC."
Your example was the scenario where there is no SDP in the 200. I would have expected that the treatment would be the same whether the offer or the answer was expected in the 200.
Regards, David
[EMAIL PROTECTED] wrote:
Hi
Quoting from RFC 3261:
'If the INVITE does not contain a session description, the UAS is being asked to participate in a session, and the UAC has asked that the UAS provide the offer of the session. It MUST provide the offer in its first non-failure reliable message back to the UAC. In this specification, that is a 2xx response to the INVITE."
so, the behavior of Cisco AS5350 is not as per the RFC 3261, since it should not send the offer in 183 non reliable response. The UAC which is receiving the offer should discard it since offer is not as per the RFC 3261.
But the problem is Cisco AS5350 can not send the offer in 200 ok, since it already sent the offer in 180, so what should be the behavior of UAC, when it did not receive any offer.
INVITE ( with out offer ) UAC --------------------------------------> Cisco AS5350
100 ( with out offer since not reliable) UAC < -------------------------------------- Cisco AS5350
180 ( with out offer since not reliable) UAC < -------------------------------------- Cisco AS5350
200 ( with out offer ) UAC < -------------------------------------- Cisco AS5350
ACK ( with out answer ) UAC -------------------------------------- > Cisco AS5350
Now the dialog will be establised with out any offer and answer. Whether this dialog is allowed ??? Whether RFC is telling anything about the dialog with out offer and answer.
Regards, Thangarajan.
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