Network restarts

I'm running a linuxbox firewall/router at home that is always on.
However when I power up a client computer on the LAN connected
to the router-box the network is dead, no traffic, no ping and
so on. I found the workaround for this is to do a:
ifdown eth0 ; ifup eth0 (eth0 beeing the nic for the LAN)
on the router-box. This "wakes up" the connection and everything
is fine. I tested both linux and winXP and in both cases I get
a "dead" network on powerup or reboot. Its slightly annoying to
go through this procedure everytime so any help on the matter would
be nice.


Fry