Subject: Re: [dhcwg] Muti-homing support.

From: HYUN WOOK CHA <[email-masked]>
Date: Thu, 07 Aug 2008 00:08:11 +0000 (GMT)

David,

<snipped>
I don't think a client can infer from multiple prefixes that there are
therefore multiple administrative domains.

I think it's possible one admin. would erect two servers, for fault
tolerance, expecting the clients to bind to only one of them (maybe
even setting the preference to prefer one prefix).

It occurs to me today - we (or I at least) keep talking about
disparate administrative domains.  Why don't we just make an option
that advertises the administrative domain explicitly?

Similarly to the choice a user expects in their desktop drop-down box
to select a WiFi network by name, a system could offer the choice of
multiple administrative sources of configuration by name (and perhaps
by URL), and default to 'all'.
</snipped>

The reason why I suggest to utilize on-link prefix-list for the decision of choosing multiple servers is that I think that multi-homing is solely relevent to the network topologies instead of administrative domains. Even though different administrative domains means different network attachements which equals multi-homing, I do not see any reason that multi-homing should not be allowed under single domain when clients can see different on-link prefixes advertised by multiple routers. IMO, this is the case for clients which are multi-homed with SLAAC. 

Joseph

-- 
Ash bugud-gul durbatuluk agh burzum-ishi krimpatul.
Why settle for the lesser evil?	 https://secure.isc.org/store/t-shirt/
-- 
David W. Hankins	"If you don't do it right the first time,
Software Engineer		     you'll just have to do it again."
Internet Systems Consortium, Inc.		-- Jack T. Hankins

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From: "David W. Hankins" <[email-masked]>
Date: Thu, 7 Aug 2008 15:48:55 -0700

> The reason why I suggest to utilize on-link prefix-list for the decision of choosing multiple servers is that I think that multi-homing is solely relevent to the network topologies instead of admin…

A single administrative domain only needs one DHCPv6 server, or
consistently (or intentionally inconsistently) configured multiple
DHCPv6 servers.

So today you can multihome in one administrative domain, and this
would not change.

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From: "Teco Boot" <[email-masked]>
Date: Fri, 8 Aug 2008 09:48:52 +0200

Address selection in a multihomed MANET is a topic to be addressed in
Autoconf WG also. The problems are not explained in detail in the problem
statement (draft-ietf-autoconf-statement-04.txt), but it is in scope (see
R12).

I published a solution for address generation for MANET Routers (Autoconf is
only chartered for this), based on a Border Router Discovery Protocol
(BRDP), see draft-boot-autoconf-brdp-00.txt. A next version will add better
support for DHCPv6, for prefix delegation for the Mobile Network (on this
link, normal hosts are attached). The MANET Router will act as DHCP Client
and collocated Relay. The BRDP information is to be used for selecting the
best Border Router (e.g. the best link to the Internet).

Recently, I had discussions on using the BRDP proposal in multihomed
enterprise networks, with PA addresses. The BRDP provided info is to be used
for source address selection / DNS updates, also for hosts (updated for
using BRDP, of course). This approach pushes functionality to the edge of
the network, in line with one of the  Internet principles.

I am working on a proposal for BRDP based routing. Using a routing header,
it is assured that the source address corresponding Border Router is used
and thus no ingress filtering problems occur.

Comments are welcome.

Regards, Teco