ethernet link

[volleyman]

all,

I have an 1841 router, I am plugging my laptop into fe0/1. using auto/auto i get link and everything is working fine.

when I plug in a different device, I get no link. I have tried all of the speed/duplex settings. it will go up/up status for a second or 2 but then it goes right back into up/down status.

I have plugged this particular device into both fe0/0 and fe0/1 with no luck. I have used different cables.

weirdly, I can plug my laptop directly into the device in question and get link right away, its just device to router that isn't working.

any ideas?

Zane D.
Systems Admin

 

[volleyman]

i found the answer...a crossover cable...weird.

the device in question is an ATM machine. it basically has a small, old PC inside. no idea why it requires a crossover, but it worked.

Zane D.
Systems Admin

 

[QuinceOcha]

It requires a cross-over cable because the atm machine is supose to go through a switch instead of going straight to the router. Anytime you are connecting two like devices without going through a switch it needs to be crossed so the send and recieve pairs match up correctly.

 

[Quadratic]

I should add, you'd usually need a crossover cable to connect a router's FastE port to a laptop NIC (not many cases where you'd do that, though). It's likely that autodetect is supported there, hence it working with a straight-through in your test.

CCNP, CCDP