[OpenSIPS-Users] detecting mediaproxy across multiple opensips instances

[Dan Pascu]

On 9 Jun 2009, at 11:58, Iñaki Baz Castillo wrote:

> 2009/6/9 Dan Pascu <dan at ag-projects.com>:
>>> Is there a way the second Opensips proxy can detect the fact the
>>> first one
>>> has already engaged the mediaproxy?
>>
>> You could add a SIP header and not start mediaproxy if present. Or  
>> use
>> some heuristics on the IP addresses from the SDP (origin IP vs c=  
>> line
>> IP). Or depending on your topology, you can know that a certain proxy
>> has a special relationship with the caller/callee and it's the only
>> one that should call engage_media_proxy()
>
> nathelper module (RtpProxy) adds a SDP line when force_rtpproxy()
> success and modifies the message:
>  a=nortpproxy:yes
>
> In case other proxy also tries to use RtpProxy for a request already
> forzed by other proxy, then "force_rtpproxy()" will return "false"
> since it detects the line "a=nortpproxy:yes" in the SDP so the second
> Rtpproxy is not used and $rc is false.
>

Having to rely (and depend) on what other proxies do, for your own NAT  
traversal is a bad design decision.

> However, this is required in RtpProxy since it doesn't allow a
> RtpProxy talking with other (dead lock would occur). This doesn't
> happen in MediaProxy.
>
>
> -- 
> Iñaki Baz Castillo
> <ibc at aliax.net>
>
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--
Dan