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New Member

T1 up/down

Getting up/down on interface and the configs are right because I've configure over 50 sites with the same configs and they work.

What can I look for? Below are the configs I've been using:

interface Serial0/0/0

bandwidth 1536

ip address

ip accounting output-packets

encapsulation ppp

service-module t1 timeslots 1-24 speed 64

description MPLS Circuit -

service-policy output ETMS

service-module t1 clock source line

service-module t1 data-coding normal

service-module t1 framing esf

service-module t1 linecode b8zs

service-module t1 lbo none

service-module t1 remote-alarm-enable

service-module t1 fdl both


I don't think the problem is on my end but I've been wrong before.

Can the smart jack cause this also? I've had this happen in my lab were I used the wrong cable.



Re: T1 up/down

If this circuit was never up in a healthy state I'd review my circuit configuration with my carrier to make sure the circuit is configured the way it was ordered.

This URL provides a good methodology for troubleshooting serial line problems.


Re: T1 up/down

Yes. What you have here is you see the wic but you do not see the circuit.

1. Make sure the cable from the router to the smartjack is good and correct pin out.

2. Make sure the carrier can loop up the smartjack and verify the circuit is good.

I would work with the carrier and have them provide you a loop from the smartjack facing you and see if you see a loop. Most of the time the issue is with the carrier on a condition like this, assuming you have your cables right.

New Member

Re: T1 up/down

They are able to loop the smart jack.

Serial0/0/0 is up, line protocol is down (looped)

I get the above


Re: T1 up/down

then you are seeing the circuit so you are able to see up to the smartjack but not beyond that. verify encapsulation and line coding and framing. If they say they are good you just need to make sure you are both set up for the same coding/framing and encap.

New Member

Re: T1 up/down

Just got off the horn with the provider the problem resides in their network. She said it was a cabling issue.

Thanks for the responses and I appreciate the input.

New Member

Re: T1 up/down

Serial0/0/0 is up, line protocol is down (looped)

When the loop is present you need to see what encap you are using if you using PPP you need change the encap to hdlc. then you will see Up/Up.. that will verify that your side is good... just more info to prove that the problem does not reside on your side, you can also do a hard loop on the back on the router to eliminate the WIC ..

Hope this helps

New Member

Re: T1 up/down

the link slmansfield provided was extremely helpful as were all the post and yours. I tried changing the encap also but we got it working.