> I looked for specific RFCs but I cannot find something clear. > So, the question: is it admitted that the UAS replies to the > ACK with a 400 bad request or it should simply ignore the > malformed ACK?
The ACK is a request which does not cause a response to be built/returned. RFC 3261 might contain more explicit text elsewhere; however the following is some of the implicit text indicating that a response cannot be generated for ACK. Section 17: "The client transaction is also responsible for receiving responses and delivering them to the TU, filtering out any response retransmissions or disallowed responses (such as a response to ACK)." Section 17.1: "The INVITE transaction consists of a three-way handshake. The client transaction sends an INVITE, the server transaction sends responses, and the client transaction sends an ACK." "For each final response that is received at the client transaction, the client transaction sends an ACK, the purpose of which is to quench retransmissions of the response." Section 17.1.1.3: "Although any request MAY contain a body, a body in an ACK is special since the request cannot be rejected if the body is not understood." _______________________________________________ Sip-implementors mailing list Sip-implementors@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/sip-implementors
