> As it says in the quoted string that you posted, The redirect server
> maintains transaction state for the whole SIP transaction.
> So, the redirect
> server waits for the ACK if it sent a 3xx back, it
> retransmits the 3xx until
> it receives the ACK (or until it retransmitted it 11 times).
>
> If the redirect server receives and ACK that it does not have
> a transaction
> state for, it will simply silently discard it.
It doesn't retransmit like this. For an INVITE request
it retransmits a 3xx upto 7 times waiting for an ACK
(14.4.1). For any request other than INVITE and ACK,
a server only retransmits responses on receipt of a
request retransmission (14.3.1). It never responds to
an ACK.
Cheers,
Neil.
--
Ubiquity Software Corporation, UK http://www.ubiquity.net
> Regards,
> Hisham Khartabil
> www.hotsip.com
>
> -----Original Message-----
> From: [EMAIL PROTECTED]
> [mailto:[EMAIL PROTECTED]]On Behalf Of
> Anand Vasudevan
> Sent: Thursday, 7 June 2001 1:06 PM
> To: '[EMAIL PROTECTED]'; 'Jonathan Rosenberg'
> Cc: Sunil Kumar T
> Subject: [Sip-implementors] How does Redirect server treat ACK ?
>
> Hi,
>
> bis-03 section 17.1 (Redirect server) says "After receiving a
> request other
> than CANCEL, the server gathers the list of alternative locations and
> returns a final response of class 3xx or it refuses the request. The
> redirect server maintains transaction state for the whole SIP
> transaction."
>
> a) Does it mean that Redirect returns 3xx for ACK request
> also? However,
> this contradicts the basic rule "ACK doesn't generate any response"
>
> b) Redirect can receive ACK in two ways - acknowledgement of
> 3xx for INVITE
> and erroneous ACK. Since redirect is transaction-based, how does it
> discriminate between those two ACKs.
>
> Could someone please clarify?
>
> Thanks in advance,
> Anand.
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