woods@ncar.UCAR.EDU (Greg Woods) (03/20/91)
>>Since the netmask is class B, different >>net numbers on the same interface just speak directly to each other >>without going through the router. The router is smart enough to know which >>subnets it needs to proxy arp for on each interface > [the router] gives its *own* address in the arp reply. The host > that sent the request then uses the cisco's hardware address > to get to the destination it enquired about. Sorry if what I said was unclear, but this is exactly what I meant. The hosts that are on the cable with multiple net numbers can run a class B netmask precisely *because* of this behavior of the router. With a class B netmask they would not normally send to the default route, but since the router does proxy arp for hosts on the other subnets, the packet ends up going to the router anyway which is what you want in that case. What I meant by "the router is smart enough" is that it won't proxy arp for hosts that ARE on this physical cable (assuming its interfaces are configured properly, of course). This means that hosts on this same physical cable can talk directly to each other WITHOUT going through the router, as the previous person said he was doing. --Greg