(usagi-users 01885) Re: switch problems with multicast ethernet packets?

[Hadmut Danisch <hadmut@xxxxxxxxxx>]

On Tue, Oct 08, 2002 at 08:49:21AM +0300, Pekka Savola wrote:
> > 
> > Has anyone else experienced such problems?
> 
> Yes.
> 

This problem could have severe implications on the use of
ipv6. 

I can remember to already have had problems with ethernet
multicast in a different context. 1-2 years ago I was 
performing some experiments to configure Nokia firewalls
and a Linux machine for high availability with VRRP, which
also makes use of ethernet multicast. 

Beside the fact, that the experiments were given up because
of software bugs in the available software releases, 
ethernet multicast turned out to be problematic, because
some (many?) cheap ethernet adapters don't handle these
addresses properly and must be set into promiscuous mode
to receive those packets. Promiscuous mode is something
you don't want to have in a production network.


Therefore I'd suggest to have a switch in 

  /proc/sys/net/ipv6/conf/*/

which allows to make the ipv6 code use simple
broadcasts ff:ff:ff:ff:ff:ff instead of multicasts.
It's not ipv6 conforming, but it's a workaround.


regards
Hadmut