On Mon, 9 Mar 2015, David Lang wrote:
On Mon, 9 Mar 2015, Mikael Abrahamsson wrote:
They need to make sure multicast works much better than it does today. IPv6
relies on it.
why does IPv6 rely on multicast?
Because that's how it was designed back in the 90ties, as an evolution to
how IPv4 was designed in the 70-ties and 80-ties. On a wired LAN, this is
extremely efficient.
multicast is never going to work that well on a busy wireless network,
especially one that's encrypted with a different key to each station.
That depends on how you do the multicast. Some enterprise solutions will
treat multicast as unicast and send the multicast packets as wifi-unicast
to each station subscribed to that group. That's one way of working around
the problem.
If this is a fundamental requirement of IPv6, I see it more likely that
it will mean the avoidance of IPv6 on wireless networks rather than an
avoidance of wireless networks in order to use IPv6
IPv4 relies on broadcast and that has the same problem. However, IPv6 has
more multicast than IPv4 has broadcast which makes the problem worse.
IEEE/wifi alliance are trying to replace wired networks, that means they
need to make sure things work as well in Wifi as it does in wired
networks. They're not doing a great job with this.
https://tools.ietf.org/html/draft-vyncke-6man-mcast-not-efficient-01
https://tools.ietf.org/html/draft-desmouceaux-ipv6-mcast-wifi-power-usage-00
https://tools.ietf.org/html/draft-yourtchenko-colitti-nd-reduce-multicast-00
People are working in the IETF to try to see what can be done. What does
IEEE do?
--
Mikael Abrahamsson email: [email protected]
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