I have seen more L2 switches that have broken IGMP/MLD snooping than
working ones. I am not aware of real proliferation of PIM snooping.
Snooping in transit LANs with PIM is a bad idea anyhow, and i have
tried to steer any customer who asked me away from it.
Bidir-PIM makes snooping particularily difficult. For once
you have to track DF-winner election messages (difficult) and
secondly you have to then flood all multicast to all DF winners
because you don't know which group-range is served by which RP.
IMHO, there is never enough multicast to justify this snooping complexity.
The only thing to worry about is what packets to send out from a router
to ensure the snooping doesn't screw up the traffic flow.
I would be surprised to find equipemnt that does PIM snooping by default.
So, i'd recommend to a homenet router:
-> even if you don't do PIM, send out PIM Hellos. This should
effectively make all stupid "enterprise class" IGMP/MLD snooping
switches (that often have broken IGMP/MLD snooping) send
you all multicast traffic (inhibits snooping).
-> Still send MLD/IGMP memberships to get traffic through the
L2 home equipment that has likely never heard about PIM.
I'd guess that eg: powerline equipment falls into this
category.
Cheers
Toerless
On Fri, Feb 20, 2015 at 11:04:41AM +1100, Andrew Mcgregor wrote:
> Why? PIM and MLD snooping are pretty standard on very low-end enterprise
> switches, which will be next year's midrange consumer models. If the
> dumb-as-rocks stuff goes away, that would generally make people happier.
>
> On 20 February 2015 at 05:22, Mikael Abrahamsson <[email protected]> wrote:
>
> > On Thu, 19 Feb 2015, Ted Lemon wrote:
> >
> > On Feb 19, 2015, at 1:08 PM, Mikael Abrahamsson <[email protected]> wrote:
> >>
> >>> I would like my router-to-router links to not have a lot of hosts in
> >>> them if I can avoid it.
> >>>
> >>
> >> Why is that?
> >>
> >
> > If we're going to be routing multicast within the home, we're most likely
> > going to have to use some kind of variant of PIM. Asking the L2 switches
> > people connect to the router to support both PIM and MLD snooping seem like
> > it might be asking too much.
> >
> > I might be wrong though.
> >
> > --
> > Mikael Abrahamsson email: [email protected]
> >
> > _______________________________________________
> > homenet mailing list
> > [email protected]
> > https://www.ietf.org/mailman/listinfo/homenet
> >
>
>
>
> --
> Andrew McGregor | SRE | [email protected] | +61 4 1071 2221
> _______________________________________________
> homenet mailing list
> [email protected]
> https://www.ietf.org/mailman/listinfo/homenet
--
---
Toerless Eckert, [email protected]
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