[afnog] GegaEthernet and FastEthernet probleme!

[Mohamed Lemine Ould Mohamed Vadel]

Hello,
That's my problem:
I have Cisco 3845 with two interfaces GigaEthernet and Cisco 3550 with 
FastEthernet interfaces. I confiqure my interfaces on the router and the 
switsh with the following parametres:
Speed 100 and duplex Full.
But of my router 3845 I  cannot send a ping on these neighbours.
what it could mean?
Thank you for your help.

Lemine