----- Original Message -----
From: "Arunachalam Venkatraman" <[EMAIL PROTECTED]>
To: "Straulino Heiko ICM N MC MI E72" <[EMAIL PROTECTED]>
Cc: <[EMAIL PROTECTED]>
Sent: Friday, July 20, 2001 11:54 AM
Subject: Re: [Sip-implementors] Question on handling CANCEL requests in
proxy
> Practically speaking, each request is processed in sequence. So, I would
say
> b is the answer.
> Do you have a proxy in mind that is constantly scanning incoming messages
> while processing one message?
A proxy designed to handle a high traffic load will need to operate in such
an asyncronous mode. If the location service is a separate process or a
separate system, the SIP proxy would not want to block waiting for a
response from the location server. Therefore, it would likely process more
incoming messages. If the proxy received the CANCEL before the response from
the location service came back, there is no reason it cannot terminate the
processing of the INVITE. Since it has not forward the INVITE on (because it
needs the location service response to know where to forward it), it can
generate the 487 response and just drop the response from the location
service when it arrives.
There is no need to send on an INVITE that you know you're immediately going
to CANCEL. I believe option (a) is the right thing to do, and I believe it
is within the rules of bis-03.
>
> ----- Original Message -----
> From: "Straulino Heiko ICM N MC MI E72" <[EMAIL PROTECTED]>
> To: <[EMAIL PROTECTED]>
> Sent: Friday, July 20, 2001 4:13 AM
> Subject: [Sip-implementors] Question on handling CANCEL requests in proxy
>
>
> > Hi all,
> >
> > i have a question regarding the handling of a CANCEL request in a SIP
> proxy
> > in the following
> > situation:
> > A proxy server receives an INVITE request. The request is processed
> > internally
> > (e.g. location server lookup, etc.). Before internal processing of the
> > INVITE is finished (and before the INVITE is forwarded)
> > a CANCEL request for the INVITE arrives. Now should the proxy:
> >
> > a) Stop INVITE processing and return a 487 "Request terminated" for the
> > INVITE transaction.
> > b) Nevertheless forward the INVITE request and send a CANCEL right
behind.
> >
> > The -bis03 draft reads as if 487 is only generated by user agents or
> > redirect servers, which sounds
> > like solution (b).
> >
> > Thanks in advance,
> >
> > Heiko Straulino
> > _______________________________________________
> > Sip-implementors mailing list
> > [EMAIL PROTECTED]
> > http://lists.cs.columbia.edu/mailman/listinfo/sip-implementors
> >
>
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