Subject: [Sip] Questions on UAC behavior when the response is unacceptable.

From: "Patrick Lam" <[email-masked]>
Date: Mon, 14 Apr 2003 14:03:12 +0800

Dear all:

On p.89 of RFC3261,

"If, however, it is unacceptable to the UAC, the UAC SHOULD generate an
answer with a valid session description, and then send a BYE to terminate
the session."

Questions:
1.	How is the answer carried toward the UAS?  Through ACK?
2.	Why does the UAC have to generate a valid answer, when it is going
to terminate the session right away?  I believe it wants to let the UAS know
what it will accept with the hope that the UAS will generate an acceptable
response in the next call, right??  However, there is no specification
(unless I missed it) here to state that the UAS has to 'remember" what the
UAC does not accept.  It seems to me that generating this valid answer is
quite unnecessary.
3.	Can the UAC terminate the session without sending the valid answer?
That is, can the UAC send a BYE without sending the ACK first (assuming the
UAS would know what this means)?

Thanks very much in advance,

Patrick Lam

---

From: [email-masked]
Date: Mon, 14 Apr 2003 12:53:52 +0530

Response Inline.

regds,
srikanth
Hughes Software Systems

"Patrick Lam" <[email-masked]> on 04/14/2003 12:33:12 PM

To:   [email-masked]
cc:    (bcc: Srikanth Sundaragopalan/HSSBLR)

Subject:  [Sip] Questions on UAC behavior when the response is
      unacceptable.

Dear all:

On p.89 of RFC3261,

Questions:
->Yes.
to terminate the session right away?  I believe it wants to let the UAS
know

->Here *Valid Answer* means a valid SDP formed according to the
Offer/Answer Model.
-> All streams in the Offer will be rejected by the UAC by setting the port
to 0 in this
-> Valid Answer.

3.   Can the UAC terminate the session without sending the valid answer?
That is, can the UAC send a BYE without sending the ACK first (assuming the
UAS would know what this means)?
-> NO NO.This is Protocol non-conformance.By doing this you will break two
things.
-> One you are NOT generating an ACK,which is mandatory according to RFC
3261
-> and other you are not sending an Answer for an Offer according to RFC
3264.

Patrick Lam

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