Re: [Sip] PING/PONG

inline.

Robert Sparks wrote:

>>
>>> Endpoints behind the things we are wanting to do this refresh things 
>>> to can be signaling
>>> directly with endpoints that aren't (a service provider could let 
>>> people talk to voice-mail
>>> or conference servers directly).
>>
>>
>> I don't see how that practically works in the presence of nat. If you 
>> are using tcp/tls, the thing to which you have a connection open is 
>> the only place from which you can get subsequent requests. Thus, if I 
>> make a call that lands on a voicemail server, the proxy holding my 
>> tcp/tls connection has to be on the signaling path, or it just won't 
>> work.
> 
> 
> If I can establish a tcp/tls connection to that voicemail server, then 
> subsequent requests from it can
> come back down that connection assuming we can keep it alive.

My point is, there may not (indeed, won't be) a connection to that thing 
in the first place. It would need to be established only after the call 
setup is complete. How would the client know to do that? You also have a 
race condition, whereby even if the client knew to do this, a sip 
request could arrive from the voicemail server before the client can 
establish the connection. I'm just not seeing the benefit here.

-Jonathan R.

-- 
Jonathan D. Rosenberg, Ph.D.                   600 Lanidex Plaza
Director, Service Provider VoIP Architecture   Parsippany, NJ 07054-2711
Cisco Systems
jdrosen@cisco.com                              FAX:   (973) 952-5050
http://www.jdrosen.net                         PHONE: (973) 952-5000
http://www.cisco.com

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