Mysterious missing DHCPv6 feature, was Re: How does one obtain an IPv6 DNS server when VPNing to an ASA?

[Gert Doering]

Hi,

On Thu, May 27, 2010 at 08:27:39AM -0700, David Barak wrote:
> -- On Thu, 5/27/10, Gert Doering <gert at space.net> wrote:
> 
> > Maybe my creativity is a bit limited, but please tell me
> > what sort of
> > configuration change you have in mind that would affect a
> > different
> > number of devices for "RA+DHCP" vs. "DHCP-only".
> 
> If I want to change the default gateway of hosts on my LAN, I can
> make a DHCPv4 change to do this.  Migrations or maintenance make
> this a useful attribute.

The argument was "with DHCP-only, you have to touch much less places".

If you want to change the default gateway for a given LAN, it's either
"change the DHCP server" or "change the router config", which is both
"touch one device" for me.  Not "large N".

If you want to change the default gateway for "large N" LANs at the 
same time, it won't be done with a single click in the DHCP server 
config either (and the question be permitted, "how realistic would 
that scenario be").

But thanks for agreeing that it's hard to find a scenario that backs
the claim "with RA+DHCP, I need to touch many more places than with 
DHCP-only".


> RA existed in IPv4, and was not widely used: DHCP was used for
> the default gateway instead, because operators preferred it.  

Mostly because "Microsoft didn't implement RA for IPv4" - so the
critical mass was not there.  Microsoft implemented handling of RA,
while Apple doesn't implement DHCPv6.  So what?

> Let's put the shoe on the other foot: if I don't want to deploy RA, why
> should I be forced to do so?

Nobody is forcing you.  You can configure your machines statically all
the way you want, or spend time and money to get default gateway into
DHCPv6 - either as a vendor extention or via IETF processes.

I'm purely objecting to the FUD about "with RA+DHCP, there is so much
more work than with DHCP-only".  People will read that, believe it, and
make decisions based on bad data.

Gert Doering
        -- NetMaster
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