Gautham A N wrote:
>
> hi,
> In the call flow example of 20.5, a BYE has not been sent before the ACK.
> The reason for this is not that the protocol prohibits it. It is because
> the user Bell doesnot know who among the 2 persons who answered to his
> INVITE is the 'real' Watson. Only after the media stream starts and he is
> able to talk to both the persons has he been able to ascertain to whom he
> wants to talk to ( X or Y). So, how can this example be taken to be
> saying that an ACK is mandatory ?
The ACK is mandatory, beleive me (if it takes Jonathan or Henning to con-
vince you, please ask them as well).
> Also, what about section 1.4.4 of the RFC2543 which specifically says "If
> the caller no longer wants to participate in
> the call, it sends a BYE request instead of an ACK." Has this been
> contradicted elsewhere?
This is no longer true.
> Also, should the UA not retransmitting the 200 OK , once it receives a
> BYE? Is there anything specific for or against this in the bis-03? if so,
> where?
See section 14.4.1 (of -03 bis), "... a server which transmits a final
response should retransmit it with an interval that starts at T1 [...]
Response retransmission cease when an ACK request is received or the
response has been retransmitted 7 times."
> One more thing the RFC says that though an ACK completes a succesful
> 'session establishment' it says that an ACK comprises a transaction of its
> own?
Right; but an ACK is used ONLY with an INVITE. Logically, it is a part of
the INVITE.
Regards,
- vijay
--
Vijay K. Gurbani vkg@{lucent.com,research.bell-labs.com,acm.org}
Internet Software and eServices Group
Lucent Technologies/Bell Labs Innovations 263 Shuman Blvd., Rm 1A-413
Naperville, Illinois 60566 Voice: +1 630 224 0216 Fax: +1 630 713 0184
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