Host A and B are on the same subnet. A sends ARP request(s) asking for B's MAC. For whatever reason, B doesn't respond. Will A either:
- Give up -- it can't reach B
- Send the packet to the default gateway, router R, and let it try to route it to B?
Of course, if B was on a different subnet, A would go straight to #2 above. My question is, in a case where they're on the same subnet, but ARP fails, will hosts also try #2.
When does this come up? Two cases:
A is really on a different subnet than B, but the subnet masks are misconfigured.
A and B are on the same subnet, but both in protected ports (a private VLAN), and so can't directly communicate to each other, without the router.
PS I could imagine the behavior is implementation dependent. So I'd appreciate not just a theoretical argument, but citing how a particular OS behaves, or at least citing a RFC or standard.