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BGP Neighbourship lost

Unanswered Question

Hi Experts,

we have recieved the following logs on our WAN router yesterday and faced a loss of connectivity for some time.


Nov 28 13:48:24.124: %BGP-5-ADJCHANGE: neighbor 10.63.161.14 Down Interface flap

Nov 28 13:48:25.124: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial0:23, changed state to down

Nov 28 13:48:55.125: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial0:23, changed state to up

Nov 28 13:49:12.101: %LINK-3-UPDOWN: Interface Async1, changed state to up

Nov 28 13:49:33.701: %BGP-5-ADJCHANGE: neighbor 10.63.161.14 Up

Nov 28 13:49:34.241: %LINK-5-CHANGED: Interface Async1, changed state to reset

Nov 28 13:49:39.241: %LINK-3-UPDOWN: Interface Async1, changed state to down

Nov 28 13:49:55.221: %CONTROLLER-5-LOOPSTATUS: Controller T1 0, CSU Loop-up code detected!

Nov 28 13:49:55.469: %CONTROLLER-5-UPDOWN: Controller T1 0, changed state to down

Nov 28 13:49:56.217: %CONTROLLER-5-LOOPSTATUS: Controller T1 0, CSU Loop-up code detected!

Nov 28 13:49:57.909: %LINK-3-UPDOWN: Interface Serial0:23, changed state to down

Nov 28 13:49:57.917: %BGP-5-ADJCHANGE: neighbor 10.63.161.14 Down Interface flap

Nov 28 13:49:58.909: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial0:23, changed state to down

Nov 28 13:50:56.466: %LINK-3-UPDOWN: Interface Async1, changed state to up

Nov 28 13:51:18.626: %LINK-5-CHANGED: Interface Async1, changed state to reset

Nov 28 13:51:23.626: %LINK-3-UPDOWN: Interface Async1, changed state to down

Nov 28 13:52:38.371: %LINK-3-UPDOWN: Interface Async1, changed state to up

Nov 28 13:53:23.935: %DUAL-5-NBRCHANGE: IP-EIGRP(0) 50: Neighbor 10.225.251.247 (Async1) is up: new adjacency

Nov 28 13:59:11.226: %CONTROLLER-5-LOOPSTATUS: Controller T1 0, CSU Loop-down code detected!

Nov 28 13:59:11.474: %CONTROLLER-5-UPDOWN: Controller T1 0, changed state to up

Nov 28 13:59:13.914: %LINK-3-UPDOWN: Interface Serial0:23, changed state to up

Nov 28 13:59:14.914: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial0:23, changed state to up

Nov 28 13:59:44.914: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial0:23, changed state to down

Nov 28 14:00:44.975: %CONTROLLER-5-UPDOWN: Controller T1 0, changed state to down

Nov 28 14:00:47.911: %LINK-3-UPDOWN: Interface Serial0:23, changed state to down

Nov 28 14:02:48.604: %DUAL-3-SIA: Route 10.63.161.12/30 stuck-in-active state in IP-EIGRP(0) 50. Cleaning up

Nov 28 14:02:48.604: %DUAL-5-NBRCHANGE: IP-EIGRP(0) 50: Neighbor 10.225.251.247 (Async1) is down: stuck in active

Nov 28 14:09:53.480: %CONTROLLER-5-UPDOWN: Controller T1 0, changed state to up

Nov 28 14:09:55.916: %LINK-3-UPDOWN: Interface Serial0:23, changed state to up

Nov 28 14:10:06.916: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial0:23, changed state to up

Nov 28 14:10:36.920: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial0:23, changed state to down

Nov 28 14:11:06.921: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial0:23, changed state to up

Nov 28 14:11:52.141: %BGP-5-ADJCHANGE: neighbor 10.63.161.14 Up

s6361r#sh clock


This is happening very frequently and is creating a lot of problems for us.

Please can some one help if this is a T1 issue or a config issue.

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Overall Rating: 4 (3 ratings)
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Richard Burts Thu, 11/29/2007 - 05:04
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Imran


The number of controller and interface ups and downs in this log sound more like a line issue than a config issue. Without knowing how it is configured it is difficult to know whether there is some configuration issue that is contributing to this. If you could post some configuration details and also post the output of show controller t1 it might give us more to work with.


HTH


Rick

Wilson Samuel Thu, 11/29/2007 - 07:04
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Hi,


After going through the logs I would think that its something at the L-1/L-2 issue and needs to be verified by the Service Provider.


It looks more or less like a link flap or faulty line / CSU/DSU.


Could you please ask the carrier to do a BERT test on this link make sure that link is fine from all issues.


I hope that will bring up the root cause.


Hope that helps.


Kind Regards,

Wilson Samuel

PS: Please rate all helpful posts

Richard Burts Thu, 11/29/2007 - 09:44
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Imran


Thank you for posting the config. I believe that it is helpful. It gets into an area where I do not have much experience, channelizing the T1 so that a couple of channels carry data traffic (including your BGP) and the rest of the channels for voice traffic.


I believe that it is also helpful that you posted the output of show controller T1. It does not show errors in the last 2 hours and 36 minutes. Would I be correct in assuming that the router might have been reboot 2 hours and 36 minutes before this output was generated? From the lack of errors shown on the T1 controller I am wondering if the voice equipment that is sharing the T1 might be doing something that impacts the data channels.


HTH


Rick

Sir,

I had cleared the counters before 2 hours of taking that output.

Here is a more recent output of sh cont t1-

s6361r# sh controllers t1

T1 0 is up.

Applique type is Channelized T1

Cablelength is long gain36 0db

No alarms detected.

alarm-trigger is not set

Soaking time: 3, Clearance time: 10

AIS State:Clear LOS State:Clear LOF State:Clear

Slot 3 CSU Serial #29494640 Model TEB HWVersion 7.03 RX level = -14DB

Framing is ESF, Line Code is B8ZS, Clock Source is Line.

Data in current interval (788 seconds elapsed):

0 Line Code Violations, 0 Path Code Violations

0 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)

1 Line Code Violations, 1 Path Code Violations,

0 Slip Secs, 0 Fr Loss Secs, 1 Line Err Secs, 0 Degraded Mins,

1 Errored Secs, 0 Bursty Err Secs, 0 Severely Err Secs, 0 Unavail Secs

s6361r#


One thing that I noticed was that the RX Level was showing as -14Db. Could it be a problem or is it normal?


Also I see that there are 1 Line Code Violations, 1 Path Code Violations and 1 Line Err Secs in the last 24 hours. Could it indicate anything, possibly a faulty CSU/DSU?


Thanks for your time.

Imran.


Wilson Samuel Fri, 11/30/2007 - 07:26
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Hi Imran,


Thanks for posting the config.


By this I'm certain that for the last 24 hours there are no issues with the CSU/DSU.



Secondly, I shall be humble over this to admit that I have never worked before on CAS mode T1 configuration.


Secondly, I have had once instance of a T1 link failure when the Carrier unknowingly put Loop on their side and the controller and the link went crazy. However since we had an external CSU/DSU we saw the Loop LED glow.


Over here in the message also says that it has detected a Loop, so could you please check with the Carrier if they have had no hand in this entire episode.


BTW, how is the link and router behaving now?


Looking forward from yourside,


Kind Regards,

Wilson Samuel

Richard Burts Sun, 12/02/2007 - 14:59
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Imran


I do not believe that 1 path code violation, 1 line code violation, and 1 errored second in 24 hours of operation is evidence of CSU/DSU problems.


Saying anything about a receive level of -14 is beyond my area of expertise. Perhaps someone who does have expertise in this could contribute some insight.


HTH


Rick

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