Hi,

Adding a port to the existing parameter would not be backwards compatible.
This idea has been suggested, but by using an "rport" parameter, as
described in the internet-draft:

http://search.ietf.org/internet-drafts/draft-ietf-sip-nat-01.txt

There is also the issue that SIP is not required to be symmetric (i.e. The
port number I send from does not have to match what is indicated in the
Via).

The sending element indicates support for rport and symmetric transport by
including rport without a value. The receiving element can then insert the
observed port# in the rport parameter and the response can be sent to that
port.

See the draft for all the details.

cheers,
(-:bob

Robert F. Penfield
Chief Software Architect
Acme Packet, Inc.
130 New Boston Street
Woburn, MA 01801
[EMAIL PROTECTED]

----- Original Message -----
From: "Christian Stredicke" <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Wednesday, April 17, 2002 5:57 AM
Subject: [Sip-implementors] received parameter in Via header


> Hi,
>
> the received parameter in the Via header does not include a port value.
>
> My proposal would be allowing to add a port value there as well
> (separated by colon), so that the proxy is able to return it to that
> address and port.
>
> NOTIFY [EMAIL PROTECTED] SIP/2.0
> Via: SIP/2.0/UDP anyone.acme.com;received=123.21.32.53:21323
>
> Wouldn't that make sense? It would be helpful in returning messages back
> to the sender, even if it is behind NAT.
>
> Or is it so that this causes trouble with existing equipment that sends
> messages from a port where it cannot receive anything?
>
>
> Christian
>
> _______________________________________________
> Sip-implementors mailing list
> [EMAIL PROTECTED]
> http://lists.cs.columbia.edu/mailman/listinfo/sip-implementors
>

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