[e2e] Transparent subnets with Proxy Arp

[J. Noel Chiappa]

    > From: "Jerry Zeitgeisty" <eric23 at softhome.net>

    > What was so bad about using proxy ARP to implement transparent subnets a
    > la RFC 1027?

I don't recall the specific issues any more, but they all stem from the fact
that an ARP-subnetted host *thinks* it is on the same wire as many
destinations (those which are ARP-subnetted), but in fact it's not. So there's
this router there which is invisible to the host.

It's trivial to think up things that can start to break in a situation like
that - e.g. the host thinks it knows the network MTU it shares with the
destination, but the other host might actually be on a network with a smaller
MTU. Etc, etc, etc.

    > (aside from being a violation of the e2e principle)

How is it a violation of the e2e principle?

	Noel