Slips/Errors with multiple PRI connections

[BrianSantomauro8105]

Hello everyone. I am having an issue where I am getting constant slip/errored secs on one of our 2 T1 interfaces. Quick brief background. At the beginning of June, Lightpath came to our facility and replaced there PRI equipment (Adtran devices). Shortly after we were getting lots of fax issues and it was intermittent. Sometimes faxes would go through fine sometimes they would just drop out or send incorrect amount of pages or take an hour to send 2 pages etc. Now Lightpath's solution to this was to take our fax lines and run them into their own 66 blocks going straight out the PRI's. This did solve the fax issues but my IS Director wanted me to look into why we were having the issues in the first place.

Our connection layout is as follows: 2 PRI connections (one from each Adtran device) going into T1 0/0/0 and T1 0/0/1 on our Cisco 3900 series (C3900-SPE100/K9). We have 2 connections to our Siemens PBX which are T1 0/1/0 and T1 0/1/1. We have a SIP connection to the CUCM (we have some Cisco desk and wifi phones in the facility). On T1 0/0/0 I have no slip/errored secs. On T1 0/0/1 I have 1522 slip/error secs in the last 3 15 min intervals and the slips/errors keep increasing.

I have a TAC case open for this and between the engineer and the research I have done, it definitely seems like there is a clocking issue. The TAC engineer has been really helpful but I think we are starting to run out of ideas. I am no expert when it comes to configuring VGW's but I have done some configuration in them before. I have reached out to Lightpath about this a few times but they just keep saying they have no slips/errors on their end and that there clock source is set to internal. They don't seem to be willing to go out of their way here to help even though this all started when they changed out their equipment.

I figured I would reach out here to see if anyone has run into something like this before. I did some searching and found a couple posts with semi similar circumstances but they weren't resolved from what I can tell. I am going to paste my clock and controller configs below. If you guys want me to add anymore of my configuration just let me know. Thank you for your help and time.

clock timezone EST -5 0
clock summer-time EST recurring
network-clock-participate wic 0
network-clock-participate wic 1
network-clock-select 1 T1 0/0/0
network-clock-select 2 T1 0/0/1

controller T1 0/0/0
cablelength long 0db
pri-group timeslots 1-24
description ** Lightpath Circuit 1 **
!
controller T1 0/0/1
cablelength long 0db
pri-group timeslots 1-24
description ** Lightpath Circuit 2 **

!

controller T1 0/1/0
clock source internal
cablelength long 0db
pri-group timeslots 1-24
description ** PBX -- Lightpath **
!
controller T1 0/1/1
clock source internal
cablelength long 0db
pri-group timeslots 1-24
description ** PBX -- Lightpath **
!

[chrihussey · Accepted solution]

Hello, 

It really sounds as if the problem is in the Lightpath equipment. The question to them would be although their PRIs clocking is set to internal, are they using a common or independent clock source? My bet is that they are independent and that is why you are seeing what you are.

Have you tried removing "network-clock-participate wic 1" and "network-clock-select 2 T1 0/0/1" and changing the clocking on the 0/0/1 controller to internal?

Can you post the output of "sh controller"?

Thanks

[BrianSantomauro8105]

Hi chrihussey,

Thank you for your reply. I agree with you this is a Lightpath issue. I was just on the phone with them this morning going over the situation again. I did try removing "network-clock-participate wic 1". When I did that it returned the message "%At least one pri-group was configured already for T1 0/1/0. Please remove it before changing timing mode." 

I hadn't tried removing "network-clock-select 2 T1 0/0/1" or changing the clocking on controller t1 0/0/1 to internal. I just performed these changes just now. You may have saved me here chrihussey. Since doing these two above changes I am no longer getting slips/errors on the T1 0/0/1 interface (its been for about an hour now). I will continue to monitor it.

I am attaching the "sh controller" below although slips/errors are zero now since making those changes above. Thank you very much for your help chrihussey.

[chrihussey]

Outstanding. Thanks for the update.