[SIPForum-discussion] Transport switch witin a call.

[Raj Jain]

I've not seen this being done in practice, but I think this should be
possible. For a mid-dialog request, the UAC/Proxy route set will
dictate using UDP to the next hop, but I think the behavior described
in section 18.1.1 will override that. You're probably aware that you
can face this problem in a response as well and you can't switch the
transport between a request and response in a transaction. This
problem is documented in the following draft:

http://tools.ietf.org/html/draft-gurbani-sip-large-udp-response-00

--
Raj Jain


On Wed, Jun 4, 2008 at 5:54 AM, Samir Patni
<samir_patni at persistent.co.in> wrote:
>
>
> Hi All,
>
>
>
> Can a call contain both TCP and UDP messages.
>
>
>
> From section 18.1.1 from rfc 3261
>
> "If a request is within 200 bytes of the path MTU, or if it is larger
>
> than 1300 bytes and the path MTU is unknown, the request MUST be sent
>
> using an RFC 2914 [43] congestion controlled transport protocol, such
>
> as TCP."
>
>
>
> Consider a scenario in which Invite is sent over UDP and for some other
> subsequent request (say  A).
>
>  Within the same call the Request length is more then 1300 bytes. Should
> this request A be sent over
>
> TCP?
>
>
>
> Thanks,
>
> Samir Patni
>
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