i am using 3 different network connection for my system
among that two card are of same type and one card is different type
the built in card in the motherboard is eth0
and extra two cards are eth1 and eth2

suddenly my eth1 is not detected then i have checkout the
it shows
alias eth0 e100
alias eth2 8139too

another card eth1 is not assigned, so i have modified the "modules.conf" file
alias eth0 e100
alias eth2 8139too
alias eth1 8139too

after this my network card seems to be detected and working fine

whether this is needed to make the card to be activated?