turning on comcast v6

Victor Kuarsingh victor at jvknet.com
Mon Dec 30 22:37:48 UTC 2013

On Mon, Dec 30, 2013 at 3:49 PM, Lee Howard <Lee at asgard.org> wrote:

> I'm not really an advocate for or against DHCP or RAs.  I really just want
> to understand what feature is missing.
> From:  Blake Dunlap <ikiris at gmail.com>
> Date:  Monday, December 30, 2013 3:19 PM
> To:  Ryan Harden <hardenrm at uchicago.edu>
> Cc:  Lee Howard <Lee at asgard.org>, Jamie Bowden <jamie at photon.com>,
> "nanog at nanog.org" <nanog at nanog.org>
> Subject:  Re: turning on comcast v6
> > The better question is are you using RIP or ICMP to set gateways in your
> > network now?
> I disagree that that's a better question.
> I'm not using RIP because my hosts don't support it (at least, not without
> additional configuration), and it would be a very unusual configuration,
> adding weight and complexity for no benefit.  RAs are the opposite.
> Not even sure how you would use ICMP to set a default gateway.  Maybe
> there's a field I'm unaware of.

[VK] The RIP comparison is somewhat confusing to me.  I don't see how RIP
is comparable in this context (I guess technically you can pass a default
route in RIP, but as Lee mentions, the protocol is designed for a different
purpose and requires configuration).

I guess the ICMP reference fair as Neighbor Discovery is built on ICMP
(which is a good thing in my opinion).  Perhaps the reference here was to
people not using RFC1256 in their networks?

> >
> >
> > If you don't use those now, why is RA a better solution in ipv6?
> It's built into the fundamentals of IPv6, using the Neighbor Discovery
> Protocol.  It's supported in every stack.  It's the default mode of
> operation.  To turn it off, you have to disable part, but not all, of NDP.
> (Do you also turn off RSs on all hosts?)
[VK] Although I think there may be a valid case presented for an Option, I
agree with Lee with the point that Neighbor Discovery is already built-in
so it has operational benefits in that respect.  There are many IPv6
deployments out there today in both ISPs and Enterprises, where ND/RAs are
being used - this may or may not make RAs "better" then a potential DHCPv6
router option, but we know it (RA method) works in real networks using IPv6.

As for a DHCPv6 router option case being made, if there a good reason and
technical merit, that should be made to the DHC WG, or perhaps even made at
a v6ops ops meeting and the advocate should make note of points made in
 Changes/updates to DHCPv6 have been made (as with RFC7083) when the
problem can be stated with technical merit and people are willing to work
on it.


Victor K

More information about the NANOG mailing list