On Tue, Jun 6, 2023 at 3:03 PM Jim Jackson <jj@???> wrote:
>
>
>
> On Tue, 6 Jun 2023, Dan Purgert wrote:
>
> > On Jun 06, 2023, Jim Jackson wrote:
> > > On Tue, 6 Jun 2023, Didier Kryn wrote:
> > > > Le 06/06/2023 à 04:02, Dan Purgert via Dng a écrit :
> > > > > [... a bunch of stuff describing general breakouts for 1k hosts
> > > > > as an aside discussion to the OP's question ...]
> > > > Didn't you forget that all these sensors don't speak to each other,
> > > > but they instead only speak with one single host. Given that, I'm not
> > > > sure breaking down the traffic into many local loops would bring much
> > > > improvement.
> > >
> > > From the OP's description of his proposed setup, I agree.
> > >
> > > Interestingly IPv6 over ethernet was designed to make it easier for
> > > one lan to have most hosts - it uses multicast instead of broadcast so
> > > it does depend on switches being able handle multicast reasonably
> > > inelligently. In this case I suppose it could be possible to run the
> > > setup using IPv6 link local addresses :-)
> >
> >
> > You still end up getting inundated with ARP and other types of cruft. I
> > haven't read anything that really indicates that v6 is any better at
> > handling >1k hosts in a single broadcast domain than v4 is; but then
> > again I also haven't kept as closely up-to-date with it as I did up til
> > about 2018 or so.
> >
> > (references / new reading material would be appreciated ^_^ )
>
> As far as I remember, IPv6 was designed to be more efficient on LANs. It
> was designed when many LANs were still esentially collision domains!!!
> For most of us "collision domains" are a thing of the past, though I still
> have a couple of bits of gear that use thin ethernet and a thin ethernet to
> Twisted pair repeater. But they haven't been powered up recently.
>
> IPv6 doesn't use broadcast, it uses Multicast. ARP in IPv4 is replaced by
> Neighbour Discovery in IPv6.
>
> https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/ipv6_basic/configuration/xe-3se/3850/ip6-neighb-disc-xe.html
>
> The closest you get to a broadcast is sending data to the All Nodes
> multicast group.
>
> So the question is - how good are cheap switches at implementing multicast
> at link level efficiently. So you need switches that support MLD snooping -
> MLD being the IPv6 version of IPv4's IGMP. I understand that there is an
> equivalence between IGMP and MLD.
>
> It probably eventually means instead of number of MAC addresses a switch
> can store for switching purposes, there may be some limit on space to store
> where all the members of the multicast addresses are, on a large network.
> Each new host creates at least one new multicast group.
>
> I came across this ...
>
> https://gist.github.com/njh/5c74614a92eb6c088ae9334db70df76a
>
> but didn't see a date. It appears a lot of managed switches support
> snooping but not sure about unmanaged cheap switches.
>
> This discusses some of the issues ...
>
> https://blogs.infoblox.com/ipv6-coe/how-many-ipv6-nodes-can-you-have-on-a-lan/_______________________________________________
Thank you very much!!!!!
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Re: [DNG] Request for information -…
