Hi, On Sun, Sep 21, 2014 at 08:01:49PM +0100, Tom Hill wrote: > On 17/09/14 11:07, Ignatios Souvatzis wrote: > > In IPv6, the data forwarding rules are more straight forward because > > MLD is mandated for addresses with scope 2 (link-scope) or greater. > > The only exception is the address FF02::1 which is the all hosts > > link-scope address for which MLD messages are never sent. Packets > > with the all hosts link-scope address should be forwarded on all > > ports." > > Forgive me if I'm missing some crucial element here, but wouldn't it be > possible to: > > (1) assign new multicast address for v6 WoL (and not use ff02::1) > (2) require that traffic for this address is forwarded /like/ ff02::1
Ah - but this would not work on existing switches that do MLD. That's the same reason IPv4 WoL is typically addressed to 255.255.255.255 or subnet broadcast, to result in ff:ff:ff:ff:ff:ff. Given that waking up machines isn't a frequent event (compared to other multicast traffic, where used - neighbour discovery, routing protocols, video streams, etc.), I don't feel ignoring others WoL packets on the interupt stack is a huge burden for the non-addressed machines. Do we have typical numbers? If I'd measure on my networks, I'd have about none on our work LANs, and one every couple of weeks at home. But I imagine people might want to wake every host once a night and run some backup or software update remotely; so unconcerned machines would see, say, one or two packets times the number of sleeping machines per night. How many hosts do you have per broadcast domain? more than 2**8? There's another consideration: if you do have the need, due to huge broadcast domains, nobody prevents you to make your machines subscribe to a locally assigned multicast address and send your WoL packets there. All the magic is in the data portion. So why change how switches work? -is