On Mon, Dec 30, 2013 at 3:49 PM, Lee Howard <Lee@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@gmail.com> Date: Monday, December 30, 2013 3:19 PM To: Ryan Harden <hardenrm@uchicago.edu> Cc: Lee Howard <Lee@asgard.org>, Jamie Bowden <jamie@photon.com>, "nanog@nanog.org" <nanog@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 draft-ietf-dhc-option-guidelines<http://datatracker.ietf.org/doc/draft-ietf-dhc-option-guidelines/>. 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. regards, Victor K