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Re: Home network topology



Rémi - Configuring a single-level multi-link/multi-prefix SOHO network is easy; we have implementations.

The subscriber gateway device can use a /56 or /48 (or anything shorter than a /64) prefix, and assign separate /64s from that prefix to each of the links in the subscriber network to which it is attached.

There are a couple of details; perhaps most important is to devise a way for consistent numbering of the links if interfaces are added or taken away from the subscriber gateway. The subscriber gateway has to derive RA configuration, etc., from the prefix numbering.

As you point out, more complex network topologies in the subscriber network might require a DHCPv6-PD server in the subscriber gateway.

- Ralph

On Mar 12, 2008, at Mar 12, 2008,8:57 AM, Rémi Denis-Courmont wrote:

Le Wednesday 12 March 2008 05:11:24 Brian E Carpenter, vous avez écrit :
On 2008-03-12 08:48, Rémi Denis-Courmont wrote:
...

For instance, 6to4rd is now proposing that only a /64 be assigned to a given customer. If we expect the home to be fully bridged, that's fine.
Otherwise, there's going to be an interesting problem.

Why do you think we originally recommended /48 for all SOHO customers,
with some recent pressure to accept /56 as well?

Well, for subnetting, obviously, but I don't remember seeing a document that
said how to do that subnetting in an unmanaged network.

Clearly prefix delegation has to be automated, though.

Precisely. And there will also be interesting problems when people try to do link-local multicast discovery. There has to be a reason why 802.11 is pretty
much designed to be bridged with 802.3.

If CPEs needs to be not only PD "clients" but also PD "servers", and if they need some basic form of in-site multicast routing/bridging, this may need to
be specified. Even if we mandate /56, without standard way to use more
than /64, people will resort to bridging and... address translation.

Bridging is bound to fail, if we see non-802 networks in the home.

Right. Then I'm afraid 64rd is a non-starter in its /64 form.

--
Rémi Denis-Courmont