Re: [v6ops] DHCPv6/SLAAC Make Hosts Confusing-//RE: new draft: draft-liu-bonica-v6ops-dhcpv6-slaac-problem

Lorenzo Colitti <> Wed, 30 October 2013 13:08 UTC

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From: Lorenzo Colitti <>
Date: Wed, 30 Oct 2013 22:07:52 +0900
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To: Nick Hilliard <>
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Subject: Re: [v6ops] DHCPv6/SLAAC Make Hosts Confusing-//RE: new draft: draft-liu-bonica-v6ops-dhcpv6-slaac-problem
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On Wed, Oct 30, 2013 at 6:50 AM, Nick Hilliard <> wrote:

> The premise that many people in the IETF seem to be working on is that the typical
> - or even a common - deployment case of ipv6 will involve multiple routers
> per lan segment.  I say this because every time the issue of DHCP providing
> a defgw comes up, one of the main arguments that's trotted out is that it
> will break the multiple-routers-per-lan-segment scenario.  The above 3
> paragraphs also strongly hint at this as being the target deployment.

Find me an medium or large enterprise deployment that doesn't have two
routers on every LAN segment. I'll bet almost all of them do, because they
know that if one crashes or they want to take it down for maintenance, they
have an outage, and nobody likes outages.

Now, the way - the *only* way - you do this in IPv4 is to run some failover
protocol like VRRP between the routers. In IPv6 you can do that, but you
don't have to, because all the RA protocol was designed to support multiple
sources of information and multiple routers.

There are situations in which that capability is useful, and I don't think
we should take it away.