[lug] Linux boxes drop off the net? Router problem?

[rm at mamma.varadinet.de]

On Tue, Feb 06, 2001 at 02:12:18PM -0700, D. Stimits wrote:
> Sebastian Sobolewski wrote:
> > 
> > An Explanation of ARP:
[ snipped away, btw. nice explanation ]
> 
> Based on this, is it possible the broadcast address is incorrect and
> causing this (not necessarily at the linux machine, but possibly)?

Not really since this is a broadcast on the lower layers of the 
protocol stack. The destination address of the ARP broadcast
is ff:ff:ff:ff (or 255.255.255.255) - this is not the broadcast
address of the subnet your boxes  are in (this needs to be that
way since many subnets can share an ethernet bus and a host might 
need to detect the hardware address of a gateway even if it's not
on the same subnet. Imagine a network (192.168.1.0 where the gate-
way doesn't have an IP address on that net but is on the same cable.
You could route traffic to the gateway by setting a host route like
this: route add -host xxx.xxx.xxx.xxx eth0 and the setting up a gate-
way route. Since this is a host route there is no network broadcast
address to send the ARP request to).

Ralf