[TriLUG] Is this block diagram fairly accurate?

[Michael Hrivnak]

On Fri, Apr 5, 2013 at 10:57 AM, Steve Litt <slitt at troubleshooters.com>wrote:

> On Fri, 5 Apr 2013 10:09:40 -0400
> Aaron Joyner <aaron at joyner.ws> wrote:
> > in particular that
> > computer 1&2 both have the gateway, and the gateway has both, but
> > that 1&2 don't have each other,
>
> Am I correct in assuming that the preceding sentence fragment is about
> routing -- that .1 and .2 route to .15, and .15 routes to each of them,
> but .1 and .2 don't route to each other because they are on the same
> subnet?


I think Aaron is suggesting that you show the arp cache tables here.
Pointing out that "Computer 1" and "Computer 2" don't have arp cache
entries for each other illustrates the on-demand discovery nature of arp;
those hosts (probably) aren't sending traffic to each other, so they
haven't done arp discovery on each other. In a simple scenario, they each
have one entry in the arp cache table, and that entry is the gateway.

Michael