2M leased line with input errors, crc , abort & interface reset

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Apr 16th, 2002
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i have 2 router connected point to point over a 2Mbps leased line. am unable to ping the local serial interface, and have input errors, crc, abort & interface reset whenshow serial int. what could be the cause of it

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m.prouty Tue, 04/16/2002 - 08:14
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There are many reasons why you could have this, first we to establish if the interface is up/up or up/down. I will assume that it is up/up. The problem is almost always in the cable. Cable length could be too great or too short. What is the length of the cable? Check the recommended length and see if your length is proper. How many DSXs does it cross? Are all the connectors attached properly. Start with placing a physical loopback on the port. If it is a DB 15 connector you can make loopback with a DB15 cable end and two wires. The manual that comes with the card has the pin out. I have them listed somewhere if you cannot find them. See if the interface come up/up with no CRCs. If so move you loopback down the line to the next location were you can place a loopback. Do this in both directions until you find the source of the errors.

If you are in an Up/Down state look at the configuration of the two interfaces. If there is nothing obviously wrong, move to the actual carrier circuit. Does it have 30 channels or 31? looping one interface to network line will tell you if the whole link is good from that framer to the other interface.

Hope this helps

I bet it is a cable!


ntra1 Wed, 04/17/2002 - 17:29
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michaeljmorris Thu, 04/18/2002 - 02:57
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is the interface up/up on both ends ?

are you using an external CSU or and internal on in the router ?

check the CSU for timing slips and errors. First 2 steps with circuits is check the CSU and then call the circuit provider.

hchebli Thu, 04/18/2002 - 19:51
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You said in your description that it is a leased line...is it FR? CRC, aborts and int resets are layer 1 & layer 2 problems. There could only be 2 causes, the NTU provided by the telco (if it is external) or a faulty cable.

Even though you can get CRC, aborts etc...this does not mean that are unable to ping the other end, so you also need to make sure that the configs are correct.

g.soon Wed, 04/24/2002 - 19:56
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Hi all,

thks for ur help, after much troubleshooting, we realised that the signal at telco side is weak for the first few day before it actual broke down.

Thanks for all the help.



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