Serial port up/down repeatedly

[wannaciscobe]

Hi,
I'm new to troublshooting routing issues but I've got a problem and I hope someone here could help.

My problem is this: I have 2 2501's linked back to back serial-serial with DTE/DCE cables for a home lab.

All of the interfaces perform normally except on one serial interface...it comes up...then a couple of moments later....it goes down...up/down...over and over.

I've checked all the cables that seems to be the only port having problems...any ideas?

Also, something on the same router that is REALLY ANNOYING is that it keeps looking for a tftp server over and over? and getting an error about tftp server 255.255.255.255 not found.
Can anyone tell me how this got started and how to stop it?

Thanks in advance...
Robert

 

[Guest_imported]

no service config will kill the tftp thingy
do show controller serial 0 and make sure you have the clock rate on the DCE end.


oz

 

[wannaciscobe]

Oz,
Thanks for the tip about the tftp service...I scoured all the books i have and the internet and couldn't find that...

But unfortunately...no dice on the serial port; it's still going up and down and I set the clockrate on the DCE at the other end...what's next? Could it be hardware related?

Robert

 

[wybnormal]

Is this a back to back cable or a DTE and a DCE cable screwed together? Many times hardware can be the problem.. just a crappy connection.

If you run a debug on the serial interface you might get a better idea of what is happening.'

Are configured as a simple HDLC connection or are you trying to config a frame sim?

MikeS
Find me at

http://www.packetattack.com

"The trouble with giving up civil rights is that you never get them back"

 

[Greasemonkey]

This might sound ridiculous but worth a try. If you have a long serial cable try to hang the cable so it doesn't shag. It could be your cable or the connection of the serial on the router.

 

[wannaciscobe]

Oz and Greasemonkey,
This is a DTE/DCE cable one type on each end. I've changed just about everything I can think of. I've swapped cables, I've done the whole troubleshooting matrix of that type.
This is just the default HDLC nothing fancy...I just got the routers and was just trying to "get a connection"..

You said hardware could be it..could this be a "bad interface"?


Grease monkey: the cable is about 10 inches long....thanks....

Bob

 

[wannaciscobe]

Sorry WYbenormal, I've been calling you OZ........I thought you were someone else!

 

[denodave]

I have two 1602s back-to-back via serial RJ-48s 56k. I had a similar (not identical) problem at first few tries. In my case I had to make sure that on the one side the clocking was set to source internal (dte), and on the the other side the clock source was set for line. This may not apply to the 2500s, but it is possible. The second thing was making sure the no shutdown command was in place for both serial interfaces.

Good luck! You may email me! denodave@yahoo.com