Network cards changed after kernel upgrade in Etch

[Eriberto <eriberto@eriberto.pro.br>]

Hi!

I am having problems when I upgrade the Etch in my servers. The NICs
designations are changing. For example, in a machine the NIC was eth0
with 2.6.18-4-686 kernel. After the first upgrade, the NIC was renamed
to eth1. The same fact occurs with 2.6.21-2 kernel (Etch-backports).
What is the cause of this problem?

Thanks in advanced.

Eriberto - Brazil