hi,

Thanks Shanbhag and Aman for your answers...

@Aman, does that mean a stateless proxy cannot detect retransmitted
messages from the existing protocol?

Regards,

Vineet Menon




On 30 April 2012 11:26, Aman Aggarwal <[email protected]> wrote:

> Hi Vineet,
>
> Stateless proxy cannot distinguish a retransmission since it does not
> maintain any transaction. For stateless proxy, RFC 3261 states that
>
> 16.11 Stateless Proxy
>
>   When acting statelessly, a proxy is a simple message forwarder.  Much
>   of the processing performed when acting statelessly is the same as
>   when behaving statefully.  The differences are detailed here.
>
>   A stateless proxy does not have any notion of a transaction, or of
>   the response context used to describe stateful proxy behavior.
>   Instead, the stateless proxy takes messages, both requests and
>   responses, directly from the transport layer (See section 18).  As a
>   result, stateless proxies do not retransmit messages on their own.
>   They do, however, forward all retransmissions they receive (they do
>   not have the ability to distinguish a retransmission from the
>   original message).
>
> regards,
> Aman Aggarwal
> Aricent
>
> -----Original Message-----
> From: [email protected] [mailto:
> [email protected]] On Behalf Of Shanbhag,
> Somesh (NSN - IN/Bangalore)
> Sent: Monday, April 30, 2012 10:59 AM
> To: ext Vineet Menon; [email protected]
> Subject: Re: [Sip-implementors] detect retransmitted messages..
>
> Hi Vineet,
>
> As far as stateful transaction is concerned, I think, call-id would give a
> clear enough picture of a retransmitted message, but what if it's a new
> invite for capability negotitation???
>
> [Answer] The re-INVITE shall have the incremented CSeq number and the
> retransmission shall not have.
>         This is because retransmission is normally done by Transaction
> layer in Stateful case.
>
> Regards,
> Somesh
>
>
> -----Original Message-----
> From: [email protected] on behalf of ext
> Vineet Menon
> Sent: Mon 4/30/2012 10:32 AM
> To: [email protected]
> Subject: [Sip-implementors] detect retransmitted messages..
>
> Hi,
>
> I wanted to know is there a way to detect a retransmitted message in a
> stateless and statefull proxy?
>
> As far as stateful transaction is concerned, I think, call-id would give a
> clear enough picture of a retransmitted message, but what if it's a new
> invite for capability negotitation???
>
> How to detect this in a stateless transaction??
>
>
> Regards,
>
> Vineet Menon
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