[OpenSIPS-Users] Transport follow up

[Bogdan-Andrei Iancu]

Hi Daniel,


Have you read RFC3263 about Locating SIP Servers  (with proto selection)  ?

    http://www.ietf.org/rfc/rfc3263.txt

Regards,
Bogdan

Daniel Goepp wrote:
> I had a previous question regarding default transport, and the 
> response I got was that the RFC says the order should be UDP, TCP then 
> TLS.  However after reading into this further (and some recent 
> experiences with other platforms) I'm wondering if I have a new 
> feature request for OpenSIPS.  >From the RFC 3263 - Section 4.1 
> Selecting a Transport Protocol, I read it as saying:
>
> 1.  If specified in the RURI it SHOULD use this (but doesn't have to)
> 2.  Bunch of stuff on NAPTR (which we are not doing)
> 3.  The section related to what we are doing:
>
> -----clip-----
> If no NAPTR records are found, the client constructs SRV queries for
> those transport protocols it supports, and does a query for each.
> Queries are done using the service identifier "_sip" for SIP URIs and
> "_sips" for SIPS URIs. A particular transport is supported if the
> query is successful. The client MAY use any transport protocol it
> desires which is supported by the server.
>
> This is a change from RFC 2543. It specified that a client would
> lookup SRV records for all transports it supported, and merge the
> priority values across those records. Then, it would choose the
> most preferred record.
>
> If no SRV records are found, the client SHOULD use TCP for a SIPS
> URI, and UDP for a SIP URI. However, another transport protocol,
> such as TCP, MAY be used if the guidelines of SIP mandate it for this
> particular request. That is the case, for example, for requests that
> exceed the path MTU.
> -----clip-----
>
> The way I read this is that OpenSIPS MAY select whatever transport it 
> likes, and if no DNS SRV is found, then it would default to using UDP 
> first for SIP.  But in our set, DNS SRV does exist, and there are both 
> TCP and UDP records.  We would like to decide the default transport 
> order to use, starting with TLS then TCP then UDP.  I think I can try 
> to write something in the script to do this, but I'm not sure yet.  I 
> don't want to rewrite the RURI, I just want to specify the transport.  
> It would be great if there was a global variable defined in the config 
> that was something like "transport_order=TLS,TCP,UDP"
>
> Thoughts?
>
> -dg
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-- 
Bogdan-Andrei Iancu
www.voice-system.ro