ARP requests on my net?

[Les Mikesell]

On Tue, 2006-04-04 at 23:20, Mike McCarty wrote:

> But my machine is not configured to be a router, bridge, or gateway.
> Doesn't mean that it isn't prepared to be one, I know.
> But why would it need the MAC for the router?

Any packet sent over ethernet needs a destination MAC address.

> Umm, maybe a little more concreteness would help...
> 
> [PSTN]<-ADSL-LINE->[DSL MODEM]<-E-NET->[ROUTER]<-E-NET->[COMPUTER]

It doesn't matter if there are only two devices on the
ethernet - the delivery mechanism is the same.

> There is not and cannot be a "next hop". The computer is a terminal.
> The only connection my computer has is to the router. I realize
> that the setup does not necessarily take this into account.

The router is the next hop for anything the computer sends.  The
computer must know its MAC address to send there.

> > traceroute www.google.com
> > 
> > will give you an idea of how many times that could happen.
> 
> I'm familiar with traceroute.

Traceroute is an IP concept that doesn't have anything to
do with ethernet or arp except that those might be used
in the transport along some of the hops.  Traceroute works
by sending packets with time-to-live values that will
expire at successively more distant routers, triggering an
ICMP response that can be used to track the route.

-- 
  Les Mikesell
   lesmikesell at gmail.com