[RTG-DIR]Re: [pim] Re: [Last-Call] Re: Rtgdir last call review of draft-ietf-pim-3810bis-10

[David 'equinox' Lamparter <[e-mail]>]

On Tue, Jul 23, 2024 at 10:35:25PM -0700, Stig Venaas wrote:
> The MLDv2 bis document is not defining a new protocol, we are just
> progressing MLDv2 to Internet Standard. We should and cannot make any
> changes that would render existing implementations non-compliant,

Even though I threw in the mail about this, I don't have a strong
preference to making any change here.  The room discussion in 6man on
the RA draft brought up the MLDv2 bis doc and it wasn't clear what's
going on -- and if there is something to be done, it'd be rather poor
timing.

> and also, we want to only have protocol definitions that have multiple
> implementations and known to work well. Removing RA would be a pretty
> big change.

I don't think removing RA is on the table.  If anything, I think it
would be weakening the requirements to check that RA is present, i.e.
allowing receive processing without RA.  It would need to remain a MUST
to include it on send though, as the sender has no idea if the receiver
(be it router or snooping switch) allows this.

> I'm not sure why MLDv2 is defined with RA, might it make a difference
> to snooping switches?

I don't believe it does, AFAIK the same mechanisms filter out e.g.
ICMPv6 RA guard, which doesn't have router alert on it.

Cheers,


equi
(David)


P.S.: our (relatively recent, 2yo) MLD implementation requires RA;  if
anything I'd like to know if I can and/or should remove that check.
https://github.com/FRRouting/frr/blame/bd86964db816ba1ac628f1b1f5099fd35f157ea5/pimd/pim6_mld.c#L1712