Re: [homenet] biggest L2 domain

[Juliusz Chroboczek]

> 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.

Section 3.3.2?

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Re: [homenet] biggest L2 domain

[Michael Richardson]

Ted Lemon  wrote:
> If it turns out that there is some performance benefit to making a
> port-to-port, point-to-point link for the router pair, then we can do that
> adaptively. That’s an optimization: it need not be where we start, and 
indeed
> back when we were initially working on this, I don’t think there was any
> assumption that we would try to constrain links to being either
> point-to-point or multi-station.

I'm not arguing for doing this.
I'm asking what happened to the text that said that we weren't.

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Re: [homenet] biggest L2 domain

[Michael Richardson]

Gert Doering  wrote:
> 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.

It wasn't intended to be automatic, but rather based upon provisioned
knowledge that a device had.

The intent was to avoid routing-at-layer-two (i.e. spanning tree, etc.), but
not to replace switches.

--
]   Never tell me the odds! | ipv6 mesh networks [
]   Michael Richardson, Sandelman Software Works|IoT architect   [
] m...@sandelman.ca  http://www.sandelman.ca/|   ruby on rails[

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Re: [homenet] biggest L2 domain

[Ted Lemon]

On Dec 13, 2019, at 12:26 PM, Gert Doering  wrote:
>> On Fri, Dec 13, 2019 at 09:54:08AM -0500, Michael Richardson wrote:
>> 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 :-)

Homenet in general is an interesting challenge—that was kind of a given when we 
started.   It’s definitely true that at least some substantial part of the 
Homenet effort, specifically the CeroWRT work, assumed one link per port.

Unfortunately, what we’ve seen is that multi-router vendors are _all_ assuming 
a flat link layer: bridging rather than routing.   This isn’t ideal in some 
ways, but it does give much better UX than having e.g. every WiFi AP on a 
different link, because the latter case results in routine connection dropping.

If we want to do better than the current state of the art in the market, we 
need to not adopt solutions that provide worse UX.   So one-link-per-port and 
one-link-per-AP is probably not a good direction to go.   If we want to 
accomplish whatever that accomplishes, we should figure out how to do it in a 
way that doesn’t reduce usability.

As for the HNCP case, there’s actually no reason why we need to assume that 
because two routers are plugged into the same link, it’s a point-to-point link. 
  If there’s more than three stations plugged into the “link” and two of them 
are routers, then the two routers can use the link for transit, and the other 
stations can use it for connectivity.

If it turns out that there is some performance benefit to making a 
port-to-port, point-to-point link for the router pair, then we can do that 
adaptively..   That’s an optimization: it need not be where we start, and 
indeed back when we were initially working on this, I don’t think there was any 
assumption that we would try to constrain links to being either point-to-point 
or multi-station.

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Re: [homenet] biggest L2 domain

[Ray Hunter (v6ops)]

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


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Hi,

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 
today).


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regards,
RayH

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Re: [homenet] biggest L2 domain

[Gert Doering]

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
-- 
have you enabled IPv6 on something today...?

SpaceNet AG  Vorstand: Sebastian v. Bomhard, Michael Emmer
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[homenet] biggest L2 domain

[Michael Richardson]

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!

--
]   Never tell me the odds! | ipv6 mesh networks [
]   Michael Richardson, Sandelman Software Works|IoT architect   [
] m...@sandelman.ca  http://www.sandelman.ca/|   ruby on rails[




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