Re: [mif] Comments on draft-mouton-mif-dhcpv6-drlo-00

Alexandru Petrescu <> Tue, 13 September 2011 22:18 UTC

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Date: Wed, 14 Sep 2011 00:20:16 +0200
From: Alexandru Petrescu <>
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To: Ted Lemon <>
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Subject: Re: [mif] Comments on draft-mouton-mif-dhcpv6-drlo-00
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Le 13/09/2011 23:27, Ted Lemon a écrit :
> On Sep 13, 2011, at 4:51 PM, Alexandru Petrescu wrote:
>> The existing implementation of draft-mouton-mif-dhcpv6-drlo-00 does
>> not handle renewal. We're facing too many options about it: should
>> it RENEW? Should it send an RS as well? This is up to debate. But
>> it is related only to the default route, not the other routes.
> That doesn't even make sense. Why does a default route need a
> lifetime, but the other routes don't?

Because, most if not all IPv6 implementations come with a mandatory ND
implementation.  That has the notion of "default router".  That default
router has a mandatory lifetime field.  There can be several routers on
a link acting as a "default router" and their lifetime.

RFC4861 syas "The Router Lifetime applies only to the router's
usefulness as a default router; it does not apply to information
contained in other message fields or options.  Options that need [...]"
  in sync with lifetimes communicated by ospf.

> Why do we need a default route option at all?

Because it is more important than the specific routes.  It must work
when everything else fails.

Must be distinguishable when several present; must be reliably renewed
even though no global address assigned with DHCP; must be in sync
with what RA does. Must tell the number of hops between Client the gw
address.  Etc.

If some of these aspects fail the Client without a default route may be
unreachable by arbitrary nodes trying to ICMP diagnose it.

On another hand, a specific route incompletely specified may not do that
much harm to Client.

> It doesn't look like the use case you've proposed justifies this
> option.


I am not sure whether you're saying that these aspects (interface name
resolution, number of hops, sync with ND/rt protocols) are necessary for
all other specific routes as well.  Or you're saying simply that the
currrrent draft-mif is ok as it is with its way of being extended.