Subject: Port-wise routing and NAT

From: Masataka Ohta <[email-masked]>
Date: Sat, 25 Jul 2009 00:28:32 +0900

Dear All;

After finishing to design end to end NAT (draft-ohta-e2e-nat-00.txt),
I have noticed several people working on similar idea differently
using portwise routing (draft-boucadair-port-range-*,
draft-ymbk-aplusp-*).

So, here is my comments.

1) Having IPv4 network, where port numbers also affect routing,
is equivalent to end to end NAT, though port-wise routing is
more obviously end to end. Thus, most arguments in
draft-ohta-e2e-nat-00.txt should be applicable to port-wise
routing. End to end NAT, on the other hand, can naturally
be upward compatible to legacy NAT.

2) Though port-wise routing is not NAT, proposals seems to assume
CPE or some box near CPE is legacy NAT, only to loss end to end transparency. CPE should better be end to end NAT.

3) Though proposals suggest tunneling, address translation of
end to end NAT is enough for redirection without affecting MTU.

						Masataka Ohta