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We have several MC3810's in use in our system. Both voice and fax work well
on all of them except for one that is attached to a Mitel SX2000 PBX (the
others are all on Mitel SX200's.) On that one faxes often fail during
transmission and if they succeed they always shift down to only 2400 baud.
I suspect that we have a clocking problem but I don't know how to solve it.
The T1 controller has automatically switched to "loop-timed" even though
I've configured it to "clock source line" There is no mention in Cisco
documenation about why a T1 Controller would decide to automatically switch
to Loop-timed.
Does anyone know?

Here's a SHOW CONTROLLER T1 1:

T1 1 is up.
Applique type is Channelized T1
Cablelength is long gain36 0db
No alarms detected.
alarm-trigger is not set
Slot 4 CSU Serial #09480883 Model TEB HWVersion 6.00 RX level = 0DB
Configured clock mode swapped to Loop-timed by priority clocking!!
Framing is SF, Line Code is AMI, Clock Source is Line.

If the Line coding is AMI should the framing not be D4?


"Ed M" <> wrote in message
news:nFtob.7750$...
> We have several MC3810's in use in our system. Both voice and fax work
well
> on all of them except for one that is attached to a Mitel SX2000 PBX (the
> others are all on Mitel SX200's.) On that one faxes often fail during
> transmission and if they succeed they always shift down to only 2400 baud.
> I suspect that we have a clocking problem but I don't know how to solve
it.
> The T1 controller has automatically switched to "loop-timed" even though
> I've configured it to "clock source line" There is no mention in Cisco
> documenation about why a T1 Controller would decide to automatically
switch
> to Loop-timed.
> Does anyone know?
>
> Here's a SHOW CONTROLLER T1 1:
>
> T1 1 is up.
> Applique type is Channelized T1
> Cablelength is long gain36 0db
> No alarms detected.
> alarm-trigger is not set
> Slot 4 CSU Serial #09480883 Model TEB HWVersion 6.00 RX level = 0DB
> Configured clock mode swapped to Loop-timed by priority clocking!!
> Framing is SF, Line Code is AMI, Clock Source is Line.
>
>

Further to that the timeslots would be 56K and not 64K as with B8ZS ESF.

"Fred Newton" <> wrote in message
news:EJWob.251536$pl3.61973@pd7tw3no...
> If the Line coding is AMI should the framing not be D4?
>
>
> "Ed M" <> wrote in message
> news:nFtob.7750$...
> > We have several MC3810's in use in our system. Both voice and fax work
> well
> > on all of them except for one that is attached to a Mitel SX2000 PBX
(the
> > others are all on Mitel SX200's.) On that one faxes often fail during
> > transmission and if they succeed they always shift down to only 2400
baud.
> > I suspect that we have a clocking problem but I don't know how to solve
> it.
> > The T1 controller has automatically switched to "loop-timed" even though
> > I've configured it to "clock source line" There is no mention in Cisco
> > documenation about why a T1 Controller would decide to automatically
> switch
> > to Loop-timed.
> > Does anyone know?
> >
> > Here's a SHOW CONTROLLER T1 1:
> >
> > T1 1 is up.
> > Applique type is Channelized T1
> > Cablelength is long gain36 0db
> > No alarms detected.
> > alarm-trigger is not set
> > Slot 4 CSU Serial #09480883 Model TEB HWVersion 6.00 RX level = 0DB
> > Configured clock mode swapped to Loop-timed by priority clocking!!
> > Framing is SF, Line Code is AMI, Clock Source is Line.
> >
> >
>
>

I tried setting the framing to both B8ZS and D4 but it made no difference.
I've just solved the problem by trying several IOS images and finally found
a very old one that works. Apparently something broke in more recent ones.
Strange

"Fred Newton" <> wrote in message
news:KqZob.253234$6C4.232876@pd7tw1no...
> Further to that the timeslots would be 56K and not 64K as with B8ZS ESF.
>
> "Fred Newton" <> wrote in message
> news:EJWob.251536$pl3.61973@pd7tw3no...
> > If the Line coding is AMI should the framing not be D4?
> >
> >
> > "Ed M" <> wrote in message
> > news:nFtob.7750$...
> > > We have several MC3810's in use in our system. Both voice and fax
work
> > well
> > > on all of them except for one that is attached to a Mitel SX2000 PBX
> (the
> > > others are all on Mitel SX200's.) On that one faxes often fail during
> > > transmission and if they succeed they always shift down to only 2400
> baud.
> > > I suspect that we have a clocking problem but I don't know how to
solve
> > it.
> > > The T1 controller has automatically switched to "loop-timed" even
though
> > > I've configured it to "clock source line" There is no mention in
Cisco
> > > documenation about why a T1 Controller would decide to automatically
> > switch
> > > to Loop-timed.
> > > Does anyone know?
> > >
> > > Here's a SHOW CONTROLLER T1 1:
> > >
> > > T1 1 is up.
> > > Applique type is Channelized T1
> > > Cablelength is long gain36 0db
> > > No alarms detected.
> > > alarm-trigger is not set
> > > Slot 4 CSU Serial #09480883 Model TEB HWVersion 6.00 RX level = 0DB
> > > Configured clock mode swapped to Loop-timed by priority clocking!!
> > > Framing is SF, Line Code is AMI, Clock Source is Line.
> > >
> > >
> >
> >
>
>