[SIPForum-discussion] Regarding Route Header

Tomasz Zieleniewski tzieleniewski at gmail.com
Wed Jun 10 09:25:22 UTC 2009


Here is a very nice example

- Tomasz

2009/6/10 SIP Babie <sipbabie at gmail.com>

> Hi,
> Thanks Tomasz for the reply.
> I am still not very clear. It will be great if you or any other member of
> the forum explain this difference with example. I will really appreciate if
> diagramatic explanation will be provided where 2 or more proxies with 2 UAC
> are taken into example.
> Regards,
> Babie.
> On Wed, Jun 10, 2009 at 1:45 PM, Tomasz Zieleniewski <
> tzieleniewski at gmail.com> wrote:
>> Hi,
>> Route header is used by UAC cores (initiator of the request) to force
>> downstream request
>> routing, through the provided list of intermediary nodes. For for instance
>> outbound SIP Proxy
>> mechanism.
>> The Record-Route header is inserted into the dialog creating requests by
>> intermediate
>> nodes (proxies) to force future requests sent within this dialog to be
>> routed through this set of proxies,
>> so called "route set". Ofcaurse if there are no Record-Route headers route
>> set is empty.
>> Route set is established during dialog creation and it can not be changed
>> later on
>> during further dialog transactions. When UAS receives initial dialog
>> creating request with a list of
>> Record-Route headers it constructs a route set and any further request
>> sent within this dialog will
>> initially contain a list of Route headers build from the previously
>> received Record-Route list.
>> Similarly UAC but in this case UAC will receive a route set in the dialog
>> creating response (both early and final).
>> Any further request sent by UAC  within this dialog will initially contain
>> a specific list of Route headers.
>> So usage of Route header is a general behaviour compliant with RFC3261
>> called loose routing,
>>  and Record-Route mechanizm simply utilizes the Route header
>> functionality.
>> Kind regards,
>> -Tomasz Zieleniewski
>> 2009/6/9 SIP Babie <sipbabie at gmail.com>
>>>  Hi All,
>>> I am  newbie to SIP.
>>> I will like to know the whats the difference between Route & Record-Route
>>> header?
>>> And also whats the significance of Route header.
>>> I know Record-Route header is been added by proxies, so that all the
>>> further SIP messaging will be passed via
>>> proxies after an initial INVITE. I would like to know who adds Route
>>> header and how Route header are been manipulated by proxies.
>>> Regards,
>>> babie
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