RE: A proposal for draft-ietf-6man-rfc4291bis-07

"Manfredi, Albert E" <albert.e.manfredi@boeing.com> Fri, 03 March 2017 02:56 UTC

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From: "Manfredi, Albert E" <albert.e.manfredi@boeing.com>
To: David Farmer <farmer@umn.edu>
Subject: RE: A proposal for draft-ietf-6man-rfc4291bis-07
Thread-Topic: A proposal for draft-ietf-6man-rfc4291bis-07
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Date: Fri, 3 Mar 2017 02:55:52 +0000
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From: David Farmer [mailto:farmer@umn.edu] 

> Because, it doesn't say IIDs are themselves required.

I see this as being a semantic game. As long as an address consists of a prefix, and it has to in order for the packet to be forwarded "the usual way" across routers, the remaining bits will be an ID pointing to a specific interface. I don’t think we are suggesting here that any prefix greater than 64 bits MUST result in a flat network. Or at least, I'm not.

> In fact it says "at a minimum, a node may consider that unicast
> addresses (including its own) have no internal structure".

As a minimum, sure, that's always the case. A node might possibly assume this, as a minimum. "As a minimum" the rule can apply to any IPv6 node, even /64 nodes. A router, for instance, might be configured to only route ten 128-bit addresses, each one to a particular egress interface, and blindly send the rest over an 11th egress interface, for all other traffic. That works fine, as long as the number of 128-bit addresses doesn't grow too much.

> And I'd now suggest it should say, if you use an IID it must be
> 64 bits unless overridden my an IPv6-over-foo spec.

But this would make "as a minimum" phrase lose all its meaning? Now it says that this flat routing scheme must be the only one allowable, for prefixes > 64. So I don’t think that's right.

Bert