Uneachable network, after update kernel to 2.6

[walking]

My previous kenel is 2.4. Because it had a problem with X server.
Today I download 2.6 and update it to 2.6 version.

I used the older configuration file. I mean, when I ran "make menuconfig", I selected to load an alternative file. Thus, I just
kept the old configuration file, and then compiled and installed it.

Finally when I restart the computer, I found network is unreachable.
I typed "route -n" and found the routing table is empty.

Yes, I didnt set up network. However, I set up it in 2.4 an kept the
same configuration file.

Why would it happen? Appreciate any help!

[burnit]

Do you use kernel modules for networking?

If it's so, you have to install module-init-tools, wich will upgrade tool for loading and manage kernel modules... you haven't installed yet, you are unable to load any kernel module... This package is a requirement for kernels 2.6.x...