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Re: Problem with Voice over ATM posted 08/19/2003
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On Tue, 19 Aug 2003, Hassan Khan wrote:

> I have two Cisco 2621 XM routers on either side. Each router is installed
> with AIM-ATM-Voice-30 Card and two VWIC-IMFT-E1 cards. The software I am
> using is Enterprise Plus. I have also tried using couple of different
> software versions and classes above Enterprise plus.
> The problem is that without getting the ATM link up I am trying to make the
> router talk to PBX system, which I think should not be a problem, however
> the router gives me an error for remote alarm.
> I am using 1,2,4,5 pinouts towards router side and PBX is also using the
> appropriate pinouts. If I look at the lights on the E1 card CD light comes
> on but AL light also starts blinking because of the remote alarm. The
> counters that increase are only (Line Code Voilation) and (Frame loss secs)
> no other counter moves. Line code is set to hdb3 and framing is set to
> No-crc4 on both sides which is router and PBX.

What is clocking the circuit?  I'm not that familiar with E-1 but your
problem sounds much like a T-1 with either two free-running clocks or
no clock.

The terminology varies from vendor to vendor, but for each synchronous
circuit, one side should be providing a clocking signal and the other
side should derive its clock from the line (and thus from the side that
provides it.)

Generally speaking, you want to receive clock from the carrier's network
if there is a carrier involved.  So, assuming your ATM interfaces are
connected to a carrier switch, those interfaces will want to have their
clock sources set to line.  If you're trying to get it set up without
the carrier's ATM nstwork connected for local testing, then you'll need
to provide clocking locally from either the PBX or the router, but you
will probably want this to be secondary to the AIM clock coming from
the ATM carrier in the production setup.

Check out the commands network-clock-select and network-clock-participate
as well as clock source.


Jay Hennigan - CCIE #7880 - Network Administration - jay@xxxxxxxx
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