Re: [homenet] Despair

[Mikael Abrahamsson <[e-mail]>]

On Thu, 6 Aug 2015, Glenn Parsons wrote:

> As I indicated in another thread, the right place to start a discussion on this would be in the IETF-IEEE 802 coordination that Dan leads.
>
> While this issue may be solved be current work underway (and included in the coordination), perhaps a clearer problem statement would help us to ensure that is the case.

There are documents that talk about multicast from a power efficiency 
standpoint:

https://tools.ietf.org/html/draft-desmouceaux-ipv6-mcast-wifi-power-usage-01
https://tools.ietf.org/html/draft-yourtchenko-colitti-nd-reduce-multicast-00
https://tools.ietf.org/html/draft-ietf-6man-rs-refresh-00

Slide 2 of 
http://www.ipv6council.be/IMG/pdf/20141212-08_vyncke_-_ipv6_multicast_issues-pptx.pdf 
pretty much sums it up, most of IETF protocols are designed around 
multicast being as reliable as unicast. IPv6 relies on this. On 802.11 
this isn't the case. Slide 5 describes how this works in 802.11.

The fact that multicast and broadcast is unreliable (not ACKed) on 802.11 
is from what I can see the major cause of the unreliability problem that 
the mesh wifi networking protocols are trying to solve by basically only 
using multicast for discovery.

The whole question is whether this should be fixed by 802.11 or if the 
IETF needs to (basically) abandon multicast/unicast, or if the IETF should 
develop a multicast->unicast replication mechanism for wifi (there is work 
in this area going on).

Personally, I think 802.11 needs to fix multicast/unicast so it's 
reliable, or get back the IETF and say it can't be fixed and then the IETF 
can continue the work on multicast reduction (or workaround) even harder.

I find the current approach of (basically) individuals within the IETF 
working on multicast reduction without (as far as I can see) any dialogue 
with 802.11 to be a non-optimal way of solving the problems we're seeing.

-- 
Mikael Abrahamsson    email: [e-mail]