Re: PLL Errors on 2501 -> PM3

Kyle Platts (kwplat1@reliant.uswc.uswest.com)
Wed, 16 Jul 97 09:15:27 -0500

>We see red blips on the Adtran TSU at least every 2 minutes, =
according to
the history on the Adtran it is a PLL error. We have had Bell =
South
looking into it, but they aren't finding any problems from their =
side,
they are willing to work with us, but neither of us know which way =
to
turn, we have tried another Adtran TSU, but it does the same =
thing. I
notice a lot of CRC errors on the Cisco when I do a sh interface =
s1, but
they don't necessarily correlate with the Red Blips I see on the =
Adtran.
By the way, the red blips are under the error light on the Adtran, =
the
funny part to me is that the Adtran will, in the history, show PLL =
error,
but does not show a Red Alarm. The PM3 doesn't show any type of =
errors on
line1, when this is happening. The Bell South tech, was =
monitoring at the
office and reported seeing a lot of timing slips.

You have a timing problem. The PM3 can only take clock from the =
loop, so the Adtran must be set up to provide clock to the span. =
The telco passes timing through the network.=20

Verify that the Adtran is set to Internal clocking under config - =
network (ni) - clock source

> Anybody have any ideas of what to try, I have tried INT and =
INT-INV
both on the Adtran for DTE TX CLK in the Port Config. On the =
network setup

These are timing options for the DTE side of the Adtran and have =
nothing to do with timing slips on the T-1.

>both sides are setup for B8ZS, ESF, the Adtran is set for =
internal clock,
because the PM3 will not supply clock. =20

Is this a full T-1? Verify the Adtran is set that way, no bit =
stuffing, 64k channels, 24 channels, continuous timeslots.

Verify the settings again. The PLL alarm indicates that the Adtran =
cannot sync up to the selected clock source.
Try changing the timing to loop and see what happens. =20

Kyle Platts
CSS-Tech
!NTERPRISE Networking Services