Solved: Connecting "fast ethernet" to "ethernet" is not working!

Abdullah Net · ‎03-05-2014

Hey there,

I connected "FE 0/1" (cisco 1841) to "Ethernet 1/0" ( NM-4E module in 2651 router). Both interfaces' status are up but their line protocol is down.

I sat both their speed to 10Mbps and their duplux to full but no luck.

Is this because i am using a straight-throught cable? According to my understanding all cisco routers uses "Auto-Mdix" feature which eleminates the need for cross-over cables.

Thanks,

Abdul,

cadet alain · ‎03-05-2014

Hi,

Auto mdix needs autonegotiation and not all devices or modules support this feature.

Regards

Alain

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View solution in original post

Jon Marshall · ‎03-05-2014

Abdul

According to my understanding all cisco routers uses "Auto-Mdix" feature which eleminates the need for cross-over cables.

Most switches support that feature but not necessarily routers. If you were using a switch module in the router then it would probably support it but i'm not sure the onboard ports do.

Jon

cadet alain · ‎03-05-2014

Hi,

Auto mdix needs autonegotiation and not all devices or modules support this feature.

Regards

Alain

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Umesh Shetty · ‎03-05-2014

HI Alain,

Another good peice of information, I was not really aware of this. I was under the impression that auto mdix works and is independent of speed/duplex settings. There definitely must be a reason behind auto mdix needing auto nego ON. If you could put some light on that too please

Regards

Umesh

cadet alain · ‎03-05-2014

Hi,

although it is a very laconic explanation, it is explained here:

http://www.cisco.com/c/en/us/td/docs/routers/access/3200/hardware/guide/C3200ISR_HWRG/MR20fesm.pdf

Regards

Alain

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Abdullah Net · ‎03-05-2014

Alain,

You are right. As it turns out, the "NM-4E" module is very very old and it lacks autonegotiation feature thus no auto-mdix.

I used cross-over cables and everything works fine now.

Abdul,

Dragan Ilic · ‎03-05-2014

Do you see something in log?

As I understand you have L2 issue - have you tried with static "half-duplex" on both sides?

HTH,
Dragan

Richard Burts · ‎03-05-2014

Alain reminds us that auto mdix needs autonegotiation and Abdul tells us that he is hard coding the speed and duplex. I think that the simple thing is to try a crossover cable and see if the connection works with that.

HTH

Rick

HTH

Rick