Solaris

your initial sample showed you have /dev/ce0 --- edit /kernel/drv/bge0.conf and set everything to 0 except for *1000fdx_cap ... if you cannot reboot your server, reset all the other capabilities off with ndd -set as listed below ... if that still does not work, have your network folks set to 1000/full the actual port speed and duplex on the switch port the affected server's cable connects to ... changing the cable will not do anything unless somebody actually dropped something on it when they changed the switches ...

Code:

ndd -set /dev/bge0 adv_1000fdx_cap 1
ndd -set /dev/bge0 adv_1000hdx_cap 0
ndd -set /dev/bge0 adv_autoneg_cap 0
ndd -set /dev/bge0 autoneg_cap 0
ndd -set /dev/bge0 1000fdx_cap 1

Yes, that was what I meant. I meant bge0 instead of ce0.
My question still stands as to why the interface fails to auto negotiate to the allocated speeds.
The second interface beg1 is connected to the same switch and is running at full duplex 1000 speed.
But in the beg0 when I force switch to 1000 speeds full duplex the link goes down. Now I am believed to think that it is because of the switch.
I read some where that there is some problem with the Cisco switches and bge interfaces, that is causing the port to act this way.
Now I am thinking of switching the port to a different port in the same switch.
I don't know anything about switches nor do I know what to look for in a switch.
I guess changing to a different switch port is my best bet.

Identify if it is a switch port issue or server issue first. If you have one server (A) running at the correct 1gb, and the other server(B) now running at 100mb, at the switch, swap server (A) cable to the switch port of server (B), and plug server(B) into the switch port server (A) was using. If it is a switch port miss-config, the problem will now move to the other server. If the same server still has the same issue, then you have at least eliminated it is a switch port issue.

The issue has been resolved now. Apparently it was because of the configurations of the switch. I am not familiar with the switches and had been asking someone who was familiar with the switches to have a look. He did and changed the configurations on the switch. Speeds back up to 1000 Full Duplex now. Thank you guys for the continuous inputs.