computer networkers, please rise

> Hi Eric,
> HOST_C and the NIC facing it on HOST_B should be on one subnet, such as
> 10.0.0.3/8 for HOST_C and 10.0.0.1/8 for HOST_B. HOST_A and the NIC
> facing it on HOST_B should be on a different subnet. You're setting up
> HOST_B as a router and so each side of the router will need to be a
> different subnet so it can make decisions about where to forward packets.


...

With Linux, is there a for-sure way to know whether my top pcmcia slot is
eth0 or eth1? I feel like linux is playing switch-a-roo on me and messing
me up. Is that possible/likely/common? I had this whole long nice reply to
some of the nice comments I received. While doing so, I accidentally
plugged the cables into what "should" have been the wrong physical
interfaces on HOST_B, but it turns out everything worked!

That is, I plugged HOST_C/10.0.x.x into what "should have been"
HOST_B/eth1/192.168.x.x while also "mistakenly" plugging in HOST_B eht0
10.0.x.x into HOST_A 192.168.x.x. But this all worked, but it "shouldn't"
have because of my (mis)understanding as to which physical interface was
assinged the logical interfaces eth1 or eth0. Does that make sense? How
can I tell which is really assigned to which?