Re: Add ARP to INET or require ND6

[Mouse <mouse%Rodents-Montreal.ORG@localhost>]

> While adding the IN_IFF_TENTATIVE functionality and friends it was
> pointed out that ARP is optional with INET.
> The argument at the time being why pay for ARP if there are no real
> interfaces?

Seems to me it's more "why pay for ARP if there are no ARP-using
interfaces?", but perhaps that's what "real" actually means there.
(There are plenty of ways to transport IP packets that don't need ARP,
starting with PPP.)

> However, NS/NA (the ARP equivalent of IPv6) is not optional with
> INET6, it's forced.

> So the burning question is this:
> Should we turn NS/NA into an option or remove the ARP option?

I'd argue in favour of the former.

> I'm in favour of the latter as I would find it hard to test patches
> for the former given my restricted hardware set.

I don't think "I can't test option 1" is a good driver for technical
decisions.  I'd prefer to make it an option, comment in the config
files that INET6 without NS/NA is untested beyond making sure it
builds, with the comment to be removed if/when it gets tested.

Of course, I'm not the one doing the work.

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