[c-nsp] Slips

[Joseph Mays]

We have an AS5400 that we are using to provide PRI's to customers. It has 
the following circuits coming into it from the Telco (AT&T).

5 Trunking circuits that come across T1 ties into a t3 mux, and then are 
then delivered to a T3 port on the AS5400. ! trunking circuit that is 
connected into a T1 card on the AS5400. Several circuits to customers that 
are delivered out of the T3 through the mux to T1 tie pairs through AT&T, 
and some of which go through HDSL T1's that we provide.

We have clocking set up thusly. The T1 port that has the trunk line in it 
(Serial6/0) is set to clock source line, to get clocking from AT&T.
The TDM clock priority on AS5400 is set to Serial6/0.
The T3 that has all the other T1's is set to clock source internal, on the 
assumption that the internal clock on the AS5400 should now be synchronizing 
to the trunk line coming in on 6/0. So all the T1 channels on the T3 should 
be following the Cisco clock.
The mux is set to clocking is set on the t3 to clock source line, to get 
clocking from the T3 coming from the AS5400.
The customers at the end are all set to clock source line.

None of the trunks is having slips, but several of the AT&T customers are 
showing a slip every 10 seconds or so. The clocking chain we have set up 
seems logical to me. Is there something I'm missing? Why would the customers 
be having slips.

We asked AT&T to monitor one of the lines that we are seeing slips on. They 
watched it for a bit and said no slips are occurring, though I am seeing 
them both on the AS5400 and on the Customer router. They are performing a 
more indepth test now.