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

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

On Fri, Jul 26, 2024 at 07:12:22PM +0200, Toerless Eckert wrote:
[...]
> To the extend of router-alert i think we would want to say "MUST
> support receiving messages with router-alert, SHOULD NOT send messages
> with router alert".

This is the wrong way around.  For any kind of non-catastrophic interop
scenario, it needs to say "MUST send messages with router alert, SHOULD
process received packets with or without router alert."

This is also the only thing I would consider for the MLD bis draft -
weakening this text (multiple places):

  "[...] and if the Router Alert option is present in the Hop-By-Hop
  Options header of the IPv6 packet. If any of these checks fails, the
  packet is dropped."

i.e. adjusting this text in order to allow processing received MLD
packets without router alert option.

BUT this can create "desync" scenarios, e.g. snooping switch requires RA
option, ignores membership report, router doesn't require it, processes
it.

I think I'll switch my position from "no opinion" to "change nothing" at
this point.  Again: I have only raised this issue because it came up in
6man.  Better to have discussed and dismissed this than to regret it
later.


-equi
(David)