Troubleshoot Slip Secs Errors on Cisco Controller T1 Interfaces

We will find Slip Secs Errors on Controller T1 interfaces in Cisco Routers. If slips are present on the T1 line means there is a clocking problem from Telco provider. The Customer Premises Equipment (CPE) will need to synchronize to the clocking from the T1 provider (Telco).

Cisco#show controllers t1
T1 0/0/0 is up.
Applique type is Channelized T1
Cablelength is long 0db
No alarms detected.
alarm-trigger is not set
Soaking time: 3, Clearance time: 10
AIS State:Clear LOS State:Clear LOF State:Clear
Version info FPGA Rev: 08121917, FPGA Type: PRK4
Framing is ESF, Line Code is B8ZS, Clock Source is Line.
CRC Threshold is 320. Reported from firmware is 320.
Data in current interval (255 seconds elapsed):
0 Line Code Violations, 0 Path Code Violations
12 Slip Secs, 0 Fr Loss Secs, 0 Line Err Secs, 0 Degraded Mins
0 Errored Secs, 0 Bursty Err Secs, 0 Severely Err Secs, 0 Unavail Secs
Total Data (last 24 hours)
0 Line Code Violations, 0 Path Code Violations,
3406 Slip Secs, 0 Fr Loss Secs, 0 Line Err Secs, 0 Degraded Mins,
0 Errored Secs, 0 Bursty Err Secs, 0 Severely Err Secs, 0 Unavail Secs

Complete the following steps to correct this problem:

  1. Ensure the clock source is derived from the Telco. In the show controller t1 EXEC command output, ensure the Clock Source is line primary.

Note: If there are multiple T1s links coming into an access server, only one can be the primary source. The other T1s derive the clock from the primary source. If there are multiple T1s, ensure the T1 line designated as the primary clock source is configured correctly. You may also configure a second T1 line to provide clocking in case the primary source goes down. To do this, use the clock source line secondary command from controller configuration mode.

  1. Set both the primary and secondary T1 clock source from controller configuration mode. For example:

Cisco(config-controlle)#clock source line primary       and

Cisco(config-controlle)#clock source line secondary 1

Ensure that the T1s that you specify as the primary and secondary are both active and stable.

Note: On certain platforms (AS5350, AS5400, AS5800 etc.) the clock source is specified using the dial-tdm-clock command. For more information on clock source refer to the document Clock Synchronization for AS5xxx Network Access Servers.



Filed Under: Channelized E1/T1


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