On Thu, 6 Aug 2015, Pascal Thubert (pthubert) wrote:
It is simply unfair from the IETF to use Wi-Fi as if it was Ethernet and
then complain to IEEE that in fact it is not.
This is an interesting viewpoint. IETF isn't "using wifi as if it was
Ethernet". The customers who buy Wifi products buy it and run IP over it,
expecting it should work (because that's what the advertising says). IP
has been designed for wired ethernet (and Wifi carries ethernet frames).
As far as I can tell, 802.11 never told the IETF that it wouldn't support
multicast (really).
I'd say IETF isn't saying "IP works great over Wifi" (it doesn't really
make any claims for any L1 or L2). However, I see producers of Wifi
equipment saying that their products are great for using to connect to the
Internet, which is saying "Wifi is great for IP".
IPv6 over Ethernet makes heavy use of multicast over Ethernet, which for
the lack of a highly scalable Multicast service always ends up
broadcasted over the whole fabric.
When Wi-Fi is confused with Ethernet and the whole multi link becomes a
single layer 2 fabric, we create a crisis that will not be solved by
imputing the responsibility on the other SDO.
Which is exactly why I said that both SDOs need to do something. However,
since IP was "first" I think that 802.11 should have come to IETF a long
time ago and said that it couldn't do multicast. Basically, what I
interpret you're saying is that Wifi in its current form isn't suited to
carry IP the way IP has been designed, for a long time. That would be news
for a lot of people.
My suggestion is to finally recognize that Wi-Fi is not Ethernet, in
particular from the perspective of multicast, and provide the
appropriate L3 mechanisms for IPv6 over Wi-Fi, for which the backbone
router discussed above is one candidate solution.
It's not only IPv6, but it's also IPv4 (since it uses broadcast, but less
of it).
But what I hear here is that your opinion is that 802.11 doesn't need to
change, but the IETF needs to change for IP to work over Wifi. I'd really
appreciate some kind of official agreement from each SDOs who should do
what. If the long-term technical solution is that the IETF should change
L3 to basically avoid broadcast and multicast, then that's fine, as long
as this is agreed upon by both parties.
However, I do think that 802.11 needs to point out to its members that if
they don't implement assured multicast replication, IP doesn't work
properly. Then they can decide what should be done in the short term,
because changing IP will take quite a while.
--
Mikael Abrahamsson email: [email protected]
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