FastEthernet doesn't want to work (PLEASE HELP!)

[Mikestudent]

Hi all,
I have a problem with interconnection of two Cisco routers (2600 and 1750) using FastEthernet interfaces. When I am configuring them with "speed 10" all works fine with both half and full duplex. I can ping a router through this connection.
But if I make "speed 100" all goes down, arp cash is empty, I even do not see cdp neighbor.
I change only "speed" on FASTETHERNET interface. What's going on? Why it doesn't work and what I can do to force it to work? It makes me crazy.

Thanks in advance,
Mike

 

[astin]

try not to go crazy....

have you checked the duplex settings ? you may want to change them.
are there any collisions on the ethernet interfaces shen you do show interface ?

 

[tcvander]

After you change the speed does the line protocol come up? What happens if you just remove the speed command?
Todd VanDerwerken, CCNA, CCDA
Technical Consultant

http://www.ciscolinks.net