Cisco Systems 10008

Troubleshooting Ethernet Connections

If an Ethernet connection to your Cisco 10008 router fails to work properly, and the corresponding LINK LED is not on, check

for the following problems:

•Visually check that an Ethernet cable is connected to the correct Ethernet port on the PRE, and that the other end of the

cable is connected to an Ethernet hub that is powered on and functioning properly.

•Check to see if you are using the correct type of cable. The cable must meet the specifications given in the “Connecting to

a 10BASE-T Ethernet Network” section on page 31.

•Check if the cable might be bad or broken. Replace the cable with a known, reliable straight-through Ethernet cable,

checking to be sure the LINK LED comes on (green).

If the LINK LED is still off, it is possible that the Ethernet port might be functioning properly, but the LED is not working.

Check the Ethernet port (by trying to ping over it, for example) to determine if the problem is due to a bad LED or if the

Ethernet link is bad.

•Make sure the PRE has booted up properly:

–

The STATUS LED should be on (green).

–

If the FAIL LED is on (yellow), see the Cisco 10000 Series Internet Router Troubleshooting Guide for troubleshooting

information.

•Check the hub:

–

Look to see if the cable is connected into the correct hub port (for example, the HUB LED is on, but the LINK LED on

the PRE is not on).

–

Be sure that the cable is not connected to an uplink port.

•If the LINK LED is on (green), but the Ethernet port does not seem to be working properly, make sure that the port in

question is configured properly and is not administratively shut down. If you have a working console connection, perform

the following steps:

–

At the router prompt, enter show interface fast0/0/0. If the port is administratively down, enter these commands to

enable it:

Switch> configure terminal

Enter configuration commands, one per line. End with CNTL/Z.

Router(config-if)# interface fast0/0/0

Router(config-if)# no shut

Router(config-if)# exit

Router(config)# exit

–

Check that the Ethernet port in question has a valid IP address assigned to it.

For more information about configuring Ethernet ports, see the Cisco 10000 Series Router Line Card Configuration Guide.

If the cables, connections, power, and configuration are all acceptable, and you still cannot connect to the Ethernet port on the

PRE, you probably need to replace the PRE. Contact Cisco Technical Support for further assistance.