Hello, Since the INVITE that is sent when Timer A fires is a retransmission in the context of a single transaction, the CSeq as well as any other message element remains the same, as stated by the following passage in RFC3261, sec. 17.1.1.2:
"When timer A fires, the client transaction MUST retransmit the request by passing it to the transport layer, and MUST reset the timer with a value of 2*T1. The formal definition of retransmit within the context of the transaction layer is to take the message previously sent to the transport layer and pass it to the transport layer once more." So, basically a copy of the request is sent. As for retries after receiving a 401/407: This is another case since the retried (NOT retransmitted) INVITE is sent inside an entirely new transaction and must have a CSeq number which is 1 higher than the original, unauthenticated INVITE per RFC326, sec. 22.2 (last paragraph): "When a UAC resubmits a request with its credentials after receiving a 401 (Unauthorized) or 407 (Proxy Authentication Required) response, it MUST increment the CSeq header field value as it would normally when sending an updated request." Note that retransmissions of the retried INVITE will again have the same incremented CSeq according to the definition of a retransmission. E.g. First INVITE has CSeq 10, all retransmissions due to Timer A also have CSeq 10, possible retried INVITE with authentication credentials has CSeq 11, all retransmissions of retried INVITE also have CSeq 11 Hope this helps and best regards, Peter On Wed, Apr 6, 2011 at 5:21 AM, Nahum Nir <[email protected]> wrote: > Hi All, > > > > After A timer fires what should I do with the SCEQ (both in case of first > invite and in case of invite after 401 challenge)? > > > > Thanks, > > Nahum > > > > > > _______________________________________________ > Sip-implementors mailing list > [email protected] > https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors > _______________________________________________ Sip-implementors mailing list [email protected] https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors
