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New Member

Serial lines has alot of Input about errors

I have faced alot of input error with abort #. I did change the cable but the error still occurs. Can the Cisco 2611 router configure the "invert txclock" to compensates for phase shifts between the data and clock signals without relying to the DSU. Because the carrier provider has claimed that the lease circuit is good after test with the bert tester. The lease line speed is 128Kbps. Please advise any solution can resolve this and thanks alot in advance.

New Member

Re: Serial lines has alot of Input about errors

Aborts mean illegal sequence of one bits- typically

a bad ckt, CSU/DSU, or sending interface on remote router.

I would do loopback testing w/ HDLC encapsulation

to try to isolate where the failure is.

1- clear int serial x

2- put local loop on csu/csu back to router(DTE loop)

3- int serial x should say up/up (looped)

4- verifyy there are no input errors. if you can , out a loop at the other end of the DSU/CSU(closest to

D-marc & also put loop back towards router).

5- take loop off, and have telco put a loop back to

router at the DACS or another point in the ckt.

6- use extended ping command with data pattern of

0x0000 repeat count of 100- this will determine if

line coding is provisioned correctly.

7- do the same, with data patterns of 0xffff, again look for input errors.

8- if clean, have telco put a loop farther away, and

repeat same steps.

9- you can also do this from remote router, if you

manage it.

somewhere along these loopback tests, you'll see

input errors, and you should be to isolate where the

failure is at.

You shouldn't have to invert the clocking.

regards, Philippe

New Member

Re: Serial lines has alot of Input about errors

Hi, Thanks alot for your input. I'm not too sure about item 5 as you mentioned earlier. Can you plase elaborate more. Is it after the local loop and there is no input errors, i'll need to proceed to take off the loop and perform the remote loop ? can I use step 6 & 7 in local loop ? please advise. Thanks alot.

New Member

Re: Serial lines has alot of Input about errors


On each of these loopback tests, continue to do loops farther away from the router

, as long as you see no input errors. If you see any input errors(clear int s x before doing

ping tests), then stop there-this is where you are having a failure.

Step 5- on some dsu/csu, you can do a loop at the DTE port(closest to router)-also try

to put a loop at the other end of the dsu/csu(closest to ckt)-this will test the entire dsu/csu unit.

step 6&7- don't believe you have to do the extended pings with data patterns-those are more

useful to test the integrity of the ckt. You should be able to just send a ping on an ip address

that is on the same subnet as the serial ip-send 50-100 pings- the return of the ping will let

you know if there are any problems, in the form of input errors.

Hope that helps-Philippe

New Member

Re: Serial lines has alot of Input about errors

Thanks for your reply. I manage to solve the problem finally and the problem was actually related to the clocking (not stable-the wave form sometime show spite) from the telco site. Still wonder why the problem was solved after changing the interfaces from Aync/Sync module (NM-8AS) to Sync module (WIC-2T). Is it any different ? I've tried to change form different Async/sync to another Async/sync module but the problem still exist.

New Member

Re: Serial lines has alot of Input about errors

Are you sure that your modems are setup for 128K ??

If faster than you're making a mistake. The 8A/S module will go up to 128k Sunc without errors, and the Wic-1T is up to 2M. So if your modems are setup for lats say 512K and you are trying this on 8A/S module it just wont work. Hope this helps


New Member

Re: Serial lines has alot of Input about errors

The modem is supplier by our carrier provider (telco). It is suppose configured to 128Kbps by telco site and it should be correct because we only paid for 128Kbps. Anyway, thank for your info and hope you have additional ideas on it.

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