I have an internet connection with DSL modem,and speed 128mbps.Iam using RedHat EL 4 system.Iam unable to get the internet.when i ping the default gateway the host is unreachable.when i run the netconfig command and reassign the ipaddress etc.,and restart the network service the ethernet cards are getting up but the network connections are failing to detect.The message looks something like this:
bringing up interface eth0:
failed to detect cable link

Only on very few occasions it is getting connected.The connection is working perfectly on Windows operating system.
Please help me solve the problem.

DSL is normally a PPoE connection.

The question is: Is your DSL modem really a router that connects PPoE by itself ( The ppoe username and password are programmed into the router via a web interface ), or is it really a modem and expects the connecting computer to handle the PPoE? It sounds rather like you need to configure PPoE on your RedHat box.