[dhcwg] Renumbering DNS with stateless DHCPv6 - bug?

Tim Chown <tjc@ecs.soton.ac.uk> Thu, 13 November 2003 19:13 UTC

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Date: Thu, 13 Nov 2003 19:11:45 +0000
From: Tim Chown <tjc@ecs.soton.ac.uk>
To: dnsop@cafax.se, dhcwg@ietf.org
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Subject: [dhcwg] Renumbering DNS with stateless DHCPv6 - bug?
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Hi,

I was mulling over the renumbering scenario for hosts that use
stateless autoconf for address allocation and DHCPv6 Light (stateless
DHCPv6) for DNS options.

Let's assume either the site renumbers, or the DNS servers are
renumbered.   The latter case means that you can't just use a new
prefix on an RA as a hint to re-request DNS options via DHCPv6 Light.

With an RA method for DNS option configuration, you put the new DNS
option information in the RA.

With DHCPv6 Light for DNS option configuration, how is the client told
that DNS options have changed?  The reconfigure message seems to be
unicast to the clients, but if the DHCPv6 server is stateless, it won't
have a list of clients (with leased IPs) to send that Reconfigure
message to?

Is this a general problem for any options set by a host that only uses 
stateless DHCPv6 for options, and use RFC2462 for addresses.

One option for passing the new DNS options from the DHCPv6 Light server
to the client is a multicast Reconfigure message.    That would work 
if the DHCPv6 Light server is on link, but if relays are used and there
is no multicast routing on site, this seems to be a gap (and a case for the 
RA method - though of course with RA method you still need to reconfigure 
the router for the new RA...)

Thoughts?

Tim

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