[VoiceOps] Acme SBC geographic redundancy

[Alex Balashov]

Jason L. Nesheim wrote:

> Right, that would impact existing established calls and subscriptions.  
> However, larger problem is that in a failover condition endpoints would 
> begin sending SIP Invites to a SBC (pair) that does not have a valid 
> registration cached, and depending on the configuration, SIP port map.  
> Depending on the re-registration interval, this could result in outbound 
> call failures for anywhere for a couple minutes to an hour or more.  In 
> the reverse direction the inside SBC IP would be unique at each site.  
> This would render the metaswitch unable to contact the endpoint for PSTN 
> -> VoIP calls for the period of re-registration as well.

 From a conventional IT/IP data person's perspective, I think these 
problems are all an acceptable tradeoff given the relatively marginal 
scenario under which an Acme would fail or a facility would fail, as a 
whole.

But people with LEC backgrounds won't put up with this way of thinking, 
typically, because they're used to being regulated and under legal 
mandate to provide high availability, and used to resilience built into 
big-iron technologies that have remained relatively unchanged for a long 
time.  VoIP operators are somewhere in the middle at this point, but the 
tendency seems to be to increase their regulatory burden, in principle.

The reality is that to get this HA setup going with geographically 
redundant endpoints - including getting the routing stuff right - will 
require that you spend 90% of your resources to get the last 2% of 
reliability.  Even then, if anyone harbours delusions of fast, seamless 
protection switching, well, prepare to be disappointed.  It's not going 
to happen.  Nor should it happen.  It's just not economical, and not 
worth doing.

As long as you can get away with it from a legal perspective - and so 
far, as a VoIP operator, it seems that you can - I would advise everyone 
to calm down, stop hyperventilating about the critical distinction 
between four-9s and five-9s, and just put in the redundancy measures to 
meet enough requirements to survive commercially.

-- Alex

-- 
Alex Balashov - Principal
Evariste Systems
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