[asterisk-users] Protection switching on PRIs.

Alex Balashov abalashov at evaristesys.com
Thu Nov 29 12:05:21 CST 2007

Has anyone figured out a way to instantaneously swing over PRIs bearing 
calls in progress to another media gateway without dropping them?

Obviously, this would require a DACS of some sort.  But I am thinking
that it is possible to swing T1s over in a DACS without actually
causing the endpoint to reframe as long as the other endpoint is kept
in sync.

So, it'd be nice, for example, to bring in some PRIs through a small
DS1-level DACS, and be able to swing them over among various boxes
with quad-span Sangoma or Digium T1 cards in the event of a problem
without dropping any calls.

I do not imagine there is a way to do this easily from an engineering
point of view;  it would require constantly synchronised PRI interfaces
on the hardware and intermediate (zaptel) level, and essentially
massively parallel Asterisk and loads of RPC.  But I imagine there is
good ROI in developing something like this.

Even developing a way to transparently switch SIP calls in progress
(together with the media and dialog state) to another Asterisk
installation seamlessly would be good, if nobody wants to go through
all the other of making this work on the TDM level.  Any allowance
for that type of failover clustering?

Alex Balashov
Evariste Systems
Web    : http://www.evaristesys.com/
Tel    : +1-678-954-0670
Direct : +1-678-954-0671

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