multicast arp entry

[Eugene Grosbein]

Ruslan Ermilov wrote:

> > > The long answer could be: you could join to a single multicast
> > > group on multiple interfaces, and you will be able to receive
> > > multicast on all of them, but if you don't have multicast
> > > forwarding enabled, only one interface will be used for sending.
> >
> > That's bad. How do I enable "multicast forwarding", or, in other words,
> > do you know why ripd doesn't do it for be?
> >
> I use mrouted(8).
> 
> > On the other hand, I've got another machine with very simple configuration:
> > one fxp0 interface, one rl0 and one gif0 and started quagga/ripd.
> > Two points: tcpdump shows that multicasts go out all three interfaces
> > with right source IP and there is no arp entries for 224.0.0.9 and 224.0.0.1.
> >
> > I couldn't find what is the vital difference between these two machines yet
> > (there are so many of them).
> >
> I don't know.  Perhaps, quagga/ripd send raw IP packets in this case.

No, it does not.

I've finally found that one need not MROUTING and mrouted just to send
RIPv2 multicasts out via several interfaces and FreeBSD does it right
by default. But if outgoint multicast packet is diverted to ipacctd
accounting daemon using 'ipfw divert' then it is sent to an interface
pointed by route to 224.0.0.9 instead of right one
(no such effect for P2P interfaces, though).

I wonder if it's a fault of ipacctd or of divert's way of life.

Eugene Grosbein