A straightforward transition plan (was: Re: V6 still not supported)

Masataka Ohta mohta at necom830.hpcl.titech.ac.jp
Fri Jan 13 05:35:46 UTC 2023

Pascal Thubert (pthubert) wrote:


> For that issue at least there was some effort. Though ATM and FR
> appear to be long gone, the problem got even worse with pseudo wires
> / overlays and wireless.
> It was tackled in the IoT community 10+ years ago and we ended up
> with RFC 8505 and 8928. This is implemented in LoWPAN devices and
> deployed by millions. Allowing IPv6 subnets of thousands on
> constrained radios.

When I mentioned a problem for the first time in IPng or IPv6
(I can't find any archive, are there any?) list, Christian
Huitema mentioned it could be solved by ND over NBMA but
the problem is not NB but broadcast of Wifi is unreliable.

As such, the solutions should be based on a fact that
repeated unreliable broadcast is reliable.

> I spent a bit of time explaining the architecture issue (in mild
> terms) and solutions in
> https://datatracker.ietf.org/doc/html/draft-thubert-6man-ipv6-over-wireless-12.

Though you wrote in the draft:

	Reducing the speed at the physical (PHY) layer for
	broadcast transmissions can increase the reliability

longer packets mean more collision (with hidden terminals)
probability and less reliability.

A link broadcast domain must be same for all the members
of the link and should be defined as set of terminals which
can receive broadcast from a central station (or, stations)
with certain probability, which is why Wifi broadcast is
relayed by a central station.

>  So far we failed to get those RFCs implemented on the major stacks
> for WiFi or Ethernet.

Ethernet? Even though its broadcast is reliable?

Though Wifi bridged by Ethernet may have its own problems,
they are Wifi-specific problems.

> There’s a new thread at IETF 6MAN just now on adopting just the draft
> above - not even the solution. It is facing the same old opposition
> from the same few and a lot of silence.

You can't expect people still insisting on IPv6 as is much.

> My suggestion is still to fix IPv6 as opposed to drop it, because I
> don’t see that we have another bullet to fire after that one. For
> that particular issue of fixing ND, new comments and support at the
> 6MAN on the draft above may help.

It may be more constructive to work for proxy ARP suitable
for Wifi, which may be enforced by Wifi alliance. An RFC
may be published if Wifi industry request IETF to do so.

						Masataka Ohta

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