Those 22 bytes would probably be the keepalive for HDLC if that's what
you're running. Interface would only go up/up if layer 1 & 2 is good,
in the case of HDLC it will need to see keepalive from the other end.
"debug serial interface" on both end would be a good one to check
this.
Personally, I haven't seen one end is up/up and the other is up/down.
I can only see this happen if the telco has misroute one end to
another site which happens to have the same setting. If anyone know
any other cases, please share with us.
Clue.
On 28 Sep 2000 20:34:02 -0400, [EMAIL PROTECTED] ("Scott Meyer")
wrote:
>Odd problem that has been solved to discuss.
>
>I had a customer with 2 routers connected by a full T1. Adtran TSU CSU/DSU
>was splitting off 5 channels for voice and sending the rest to the router
>for data. Routers had no connection to the voice. Data was down but voice
>was working fine.
>
>This was a working setup, not a new install.
>
>Router A had a Up/up on the interface, was getting 22 byte packets in. No
>input errors. Not seeing any IGRP packets. I could not ping the serial
>interface on router B.
>Router B had up/down on the interface, sending (22 byte packets) and I didnt
>check if it was recieving packets, but getting lots of CRC input errors. If
>I did a local loopback on the Nx56/64 port on the Adtran, I would come up/up
>and ping myself with no CRC errors. If I pulled the T1 outta the smartjack
>and put in a hardloop, I'd be up/down and getting CRC. Replaced the Nx56/64
>module and all was well.
>
>The question is, what is the 22 byte packets coming in? What conditions need
>to be met for the protocol to go up? I've never seen it up/up and not have a
>connection.
>
>Scott Meyer
>CCNA, CCDA, MCSE, etc
>[EMAIL PROTECTED]
>
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