Re: [homenet] biggest L2 domain

"Ray Hunter (v6ops)" <> Fri, 13 December 2019 17:45 UTC

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To: Gert Doering <>
Cc: Michael Richardson <>, homenet <>
References: <20241.1576248848@localhost> <20191213172646.GI72330@Space.Net>
From: "Ray Hunter (v6ops)" <>
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Date: Fri, 13 Dec 2019 18:45:29 +0100
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Subject: Re: [homenet] biggest L2 domain
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Gert Doering wrote on 13/12/2019 18:26:
> Hi,
> On Fri, Dec 13, 2019 at 09:54:08AM -0500, Michael Richardson wrote:
>> I thought that we wrote somewhere in RFC7368 that the Homenet router should
>> collect as many ports as possible together into a single L2 zone.
>> I can't find that text right now. Did it go away?
>> In testing, we have found a device that does not put it's 5-"LAN" ports into
>> a bridge.  That's probably a missing configuration, but in the meantime, we
>> have an interesting HNCP and naming setup!
> My understanding of "homenet" and "HNCP" devices has always been "every
> single hole in the box is a routed port".  Now that's my understanding and
> not necessarily written down somewhere.
> Magically grouping ports into a common L2 network and then un-grouping
> them in case one of them turns out to have another HNCP device connected
> sounds like an interesting challenge, to say the least :-)
> Gert Doering
>          -- NetMaster
> _______________________________________________
> homenet mailing list

I agree that learning L2 topology is not trivial and is not covered in 
the current Homenet daemon.

Learning at boot time or port status change would require stopping 
forwarding to avoid loops, which is undesirable in networks where 
devices are plugged and unplugged (think wired laptop moving around 
interrupting media streaming on another device)

I was thinking of something like bringing up all ports in L3 at boot 
time, on a dedicated VLAN, see what's there, and then "annealing" the 
network later.

So if two (or more) ports are detected as only having hosts, they could 
later be merged to be one L2 domain after some period of stable operations.

One name and prefix would be primary, whilst the others would be 
configured initially but gradually removed (as leases die), which would 
be the equivalent of a phased
renumbering event with a flag day.

But other alternative of treating all ports as L3 ports forever would 
seem to require hierarchy in the naming solutions (which doesn't exist