Slip seconds and Errored seconds Impact on production

[umeshplamthottam]

Hi All,

Greetings,

I am writing this to check the impact of Slip Seconds and Errored seconds on T1/E1 controllers.

When I gone though docs and community I found that the issue is with Clock Sync. Is there any production impact for this Slip errors and Errored seconds.

Thanks in advance.

Have a great day.

[b.winter]

Hi,

Impacts are e.g. bad voice quality during calls, failing / disconnecting calls.

Issues with the clock sync should be avoided

[umeshplamthottam]

Thanks Winter for the quick update.

[chrihussey]

The impact largely depends on the severity of the issue. For example, intermittent single slips occurring every now and then or once every few minutes may go unnoticed. Constant slipping or bursts causing high amounts in short periods of time will get noticed and could degrade overall service. 

You definitely don't want slips/err seconds on your controllers. Generally, when connecting to a provider, you want to set the clocking to be off the line.

Hope this helps.

[umeshplamthottam]

Thanks Chrihussey,

For the detailed clarification. I think this helps a lot.

Is the slipping means that the connection with Service provider is disconnecting ?.

[chrihussey · Accepted solution]

A slip doesn't mean that the service is disconnecting. A T1/E1 is a digital bit stream of encoded "words" made up of ones and zeroes and the clocking maintains the timing so that they can be deciphered properly. Slips occur when the timing is momentarily out of synch and bits/words are lost. Minor slips may go unnoticed during a voice call. Severe instances of slipping can be much more noticeable and if bad enough could also affect T1/E1 call signaling and possibly carrier loss. 

[umeshplamthottam]

Thanks again for the clarification.
Have a great day ahead.

[umeshplamthottam]

How we can avoid this slips from the controller how to troubleshoot and fix the issue.

[chrihussey]

Don't know your situation but as a general rule the controller should clock off the line and not internal (or itself). If slips still occur then you can always try internal clocking to see if that works. Also check the length and condition of the cable to the router. If none of that works or if you're also seeing other errors in the form of line code violations, frame loss, etc., then you should have the provider check the circuit. Finally, if it still persists, it may be necessary to try a different controller.

Just FYI, it varies with platforms, but this is the config for clocking off a PRI line on a 4351:

!

controller T1 0/1/0
clock source line primary

!

!
network-clock synchronization automatic
network-clock input-source 2 controller T1 0/1/0

!

[umeshplamthottam]

Please see the Sh controllers E1 output

[chrihussey]

What is the E1 connected to?

If it is to a provider (phone company), then suggest having them check the circuit and verify clocking with them. If it is going to a local PBX or something along those lines perhaps one needs to be set to internal and the other off the line.