Subject: I-D ACTION:draft-huitema-ipngwg-dialondemand-00.txt

From: [email-masked]
Date: Mon, 19 Nov 2001 08:30:33 -0500

A New Internet-Draft is available from the on-line Internet-Drafts directories.

	Title		: IPv6 Dial-up on Demand
	Author(s)	: C. Huitema
	Filename	: draft-huitema-ipngwg-dialondemand-00.txt
	Pages		: 12
	Date		: 16-Nov-01
	
In an IPv6 home network, there is a possibility that the residential
gateway, learns a different IPv6 prefix after each dial-up; attempts
to communicate using old address would thus fail. This implies that
we should not attempt to trigger dial-up by simply sending the first
packet of a connection.

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From: Pekka Savola <[email-masked]>
Date: Tue, 20 Nov 2001 11:14:23 +0200 (EET)

> we should not attempt to trigger dial-up by simply sending the first

Just read this quickly..

I may have missed something, but why exactly is this necessary?  It seems 
way too complex to me.  Also, it is unclear why there would be a need for 
new ICMP types; why Echos wouldn't be enough?  All in all, dialups 
(especially for whole subnets) might be getting rarer in the years to 
come.

Wouldn't it just be sufficient that when a dial-up link goes down, the 
router advertises default router lifetime=0.  Hosts have no longer a 
default route, and all packets they send will be assumed to be on-link.

Router can see these on-link messages (or rather, neighbour discovery
attempts for foreign addresses like the DNS server), and decide to open
the dial-up link based on some heuristics.  Then router would advertise
the default route and new addresses, which would immediately be used for
re-trying DNS queries and the real communications.  If link is brought up
and down quickly so that the prefix changes, ingress filtering could
prevent old addresses from being used.

(there are probably some bugs in my above thinking, but it was just a 
rough idea..)

-- 
Pekka Savola                 "Tell me of difficulties surmounted,
Netcore Oy                   not those you stumble over and fall"
Systems. Networks. Security.  -- Robert Jordan: A Crown of Swords

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From: Nathan Lutchansky <[email-masked]>
Date: Sun, 25 Nov 2001 11:11:14 -0500

> 	Title		: IPv6 Dial-up on Demand

I don't think it's a good idea to rely on ICMP replies from a remote host,
considering how many sites filter even ICMP echos right now.  A feature
such as this should not require support from hosts outside the site.

Why not require the border router to reply to these messages, with either
a "connectivity OK" reply or a "wait for dialup" reply?  The "wait for 
dialup" reply could contain useful information like "expect a connection 
in 30 seconds" or "dialup disallowed".

This draft is worthwhile since dial-on-demand functionality would benefit
from coordination between hosts within a site and the dialup router, but
it would be unnecessary for hosts outside the site to take part.  -Nathan

-- 
+-------------------+---------------------+------------------------+
| Nathan Lutchansky | [email-masked] |  Lithium Technologies  |
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