[SR-Users] [OT] the role of SBCs

[Daniel-Constantin Mierla]

Hello,

based on the outcome of the discussion carried in the thread:

http://lists.sip-router.org/pipermail/sr-users/2012-August/074480.html

I am looking again the clarify some aspects out there in the VoIP world.

So, as mainly dealing with proxy/sip signaling deployments, it's very 
often to be the first one hit by support issues claiming things don't 
work. Then you investigate and end up in conclusions like in the above 
thread:

"The problem was at the SBC, __where I did not expect it__."

The underlined part heats me up a bit, because I never understood from 
where it comes this perception that SBC is a MUST-TO-HAVE and the 
PERFECT (never mistaken or breaking things) node in a VoIP networks.

To some extent, the SBC is just a very costly SIP ALG, and a SIP ALG is 
there to break the things.

I don't want to start like a flame war, but is it something that I am 
obviously missing in regards to what benefits a SBC can bring? I see 
only inconveniences:
- another point of failure
- it is a b2bua, therefore very unlikely to offer the same performances 
of a proxy
- if transcoding is needed, a media server can be used behind the proxy, 
properly protected of attacks by the proxy and eventually deployed as a 
farm load balanced by the proxy
- if topology hinding is wanted in the b2bua fashion (not the proxy 
fashion with encoding headers), then the b2bua can be behind the proxy, 
properly protected of attacks by the proxy and eventually deployed as a 
farm load balanced by the proxy
- nat traversal was solved long time ago in proxy environment, being 
scalable by deploying a farm of rtp proxy

I don't want to go to other features, including the transport layer, 
it's a clear win of the proxy in my experience (ok, being deep involved 
in this project).

Then, what makes the SBC so desirable in many companies/voip 
deployments? If any SBC user here that can share, what was the reason to 
buy such a device? Any conceptual functionality that cannot be achieved 
with the proxy as the first hop in front of the (wild) clients?

Cheers,
Daniel

-- 
Daniel-Constantin Mierla - http://www.asipto.com
http://twitter.com/#!/miconda - http://www.linkedin.com/in/miconda
Kamailio Advanced Training, Berlin, Nov 5-8, 2012 - http://asipto.com/u/kat