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Re: "RFC 2461bis" issue: DNS configuration



Iljitsch, I agree.  This has been discussed a lot on the dnsop list... 
there is currently no consensus about DHCPv6(Lite) vs RA-based discovery.

It will be interesting to see what the Moonv6 work may have to say in this
area, as the issue I'm sure will have been encountered there.   There are
still very few people working in networks where IPv6 transport DNS lookup
is a requirement, hence this issue has seen slow progress.

I am in the RA camp, but I agree DHCPv6 will be used for other things 
(e.g. NTP server), so in cases where a DHCPv6 server is present it will be 
able to be used for resolver discovery.  But I believe we should have a RA 
based method also.

The general thrust of the DHCPv6 camp argument is that in any situation
where a router is configured to pass DNS info in a RA extension it could
equally be configured to do so using DHCPv6 (Lite), or could forward to
a DHCPv6 server using the DHCPv6 relay agent function.

The second argument used by the DHCPv6 camp is that having two methods may
lead to complexity, and problems in troubleshooting.

The third is a fear of creeping featurism - where is the line over which
you don't step for RA extensions?   DNS resolver?  Search path?  NTP?

But there are some clear advantages for the RA method, like the ability
to multicast the information in a one-way message, where DHCPv6 must always
rely on a client-server exchange.

Both methods have security considerations.

There seem to be a handful DHCPv6 implementations, but no stripped down
DHCPv6 Lite implementations yet (the Lite version not maintaining state
for IP leases etc).

Tim

On Thu, Oct 23, 2003 at 09:18:24AM +0200, Iljitsch van Beijnum wrote:
> On 23 okt 2003, at 8:46, Soliman Hesham wrote:
> 
> >>Why is there no mechanism to learn DNS addresses through router
> >>advertisements?
> 
> >=> A couple of years ago there was a DT that compared several
> >different ways of achieving this. The proposal you mentioned
> >was one of those addressed. The DT settled on assigning
> >3 different site-local addresses that can be reserved for
> >DNS servers. The solution was documented in a draft (I believe
> >Itojun, Alain and Dave Thaler co-authored it). But this idea
> >didn't get concensus in the WG and I think the draft is dead
> >now but I'm not sure. DHCPv6 allows for DNS configuration in
> >hosts among other things.
> 
> Ok, I only have one word for this: unacceptable.
> 
> I stronly suggest everyone who was against this to try running IPv6 for 
> a few minutes.
> 
> 
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