[cisco-voip] NFAS with D Channel Back Up

[Pennington, Craig]

I agree with the notion that it prevents spreading your PRI's across
gateways.  We had a similar situation.  We migrated the NFAS group as it
was and plan to break the group.  The trick it seems is knowing which
PRI is what number in the group.  We struggled with telco (AT&T) and
getting that information.

Ours is on a CMM module.  The controller's are configured with the
following line to set its part of the NFAS group.
Controller t1 1/3
pri-group timeslots 1-24 nfas_d primary nfas_int 1 nfas_group 1
Controller t1 1/4
pri-group timeslots 1-24 nfas_d backup nfas_int 0 nfas_group 1
Controller t1 1/5
pri-group timeslots 1-24 nfas_d none nfas_int 2 nfas_group 1

The backup and primary tells it where to find the D channel and the
nfas_int tells it what the PRI's number is in the group.

Craig


From: cisco-voip-bounces at puck.nether.net
[mailto:cisco-voip-bounces at puck.nether.net] On Behalf Of Jason Aarons
(US)
Sent: Tuesday, July 29, 2008 2:58 PM
To: James Buchanan; STEVEN CASPER; cisco-voip at puck.nether.net
Cc: RAWLE GORDON
Subject: Re: [cisco-voip] NFAS with D Channel Back Up

 

IOS NFAS requires the PRIs be on same chassis with H323 which defeats
high
availability.  I would work with telco to issue change order to remove
the
NFAS and split the PRIs between two or more 28xx/38xx. You can then have
telco use Trunk Groups for incoming and you can use Route Groups/Route
Lists
for outgoing.

NFAS was great when you had one really big refrigerator PBX with full
redundancy, but when you have distributed routers it doesn't fit as
well.


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