Subject: I-D ACTION:draft-ietf-ipv6-router-selection-02.txt

From: [email-masked]
Date: Tue, 11 Jun 2002 07:05:50 -0400

A New Internet-Draft is available from the on-line Internet-Drafts directories.
This draft is a work item of the IP Version 6 Working Group Working Group of the IETF.

	Title		: Default Router Preferences, More-Specific Routes and 
                          Load Sharing
	Author(s)	: R. Draves, B. Hinden
	Filename	: draft-ietf-ipv6-router-selection-02.txt
	Pages		: 13
	Date		: 10-Jun-02
	
This document describes two changes to Neighbor Discovery. The first 
change is an optional extension to Router Advertisement messages for 
communicating default router preferences and more-specific routes 
from routers to hosts. This improves the ability of hosts to pick an 
appropriate router, especially when the host is multi-homed and the 
routers are on different links. The preference values and specific 
routes advertised to hosts require administrative configuration; 
they are not automatically derived from routing tables. The second 
change is a mandatory modification of the conceptual sending 
algorithm to support load-sharing among equivalent routers.

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From: "Richard Draves" <[email-masked]>
Date: Wed, 12 Jun 2002 21:26:12 -0700

> 3.4. Router Reachability Probing
> 
>    When a host avoids using a non-reachable router X and instead uses
>    another router Y, and the host would have used router X if router X
>    were reachable, then the host SHOULD probe router X's reachability
>    by sending a Neighbor Solicitation. A host MUST NOT probe 
> a router's 
>    reachability in the absence of useful traffic that the host would 
>    have sent to the router if it were reachable. [...]
> 
> ==> I think 'MUST NOT' there is very strict wording.  Is it really 
> necessary to be so?  Would SHOULD NOT be sufficient?

Perhaps. I added this in response to the feedback at Minneapolis, where
it was clear the earlier wording was misunderstood to mean that probing
would happen in the absence of useful traffic; perhaps I over-reacted.
Any other opinions on MUST NOT vs SHOULD NOT here?

>   When a host chooses from multiple equivalent routers, it 
> MUST choose 
>   randomly. 
> 
> ==> Did we settle this SHOULD/MUST debate?  I'm not sure if 
> MUST is best, 
> but I can deal with that.

I would be OK with SHOULD here, but I believe my newly added co-author
prefers MUST.

> 
>   Routers SHOULD NOT include in a Router Advertisement two Route 
>    Information Options with the same Prefix and Prefix Length
> 
> ==>
> s/in a Router Advertisement two Route Information Options/
>   two Route Information Options in a Router Advertisement/ ?

Then "with the same Prefix and Prefix Length" would be misplaced
modifier, no?

Thanks,
Rich

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