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To: "Michael C. Newell" <mnewell@lupine.nsi.nasa.gov>
cc: hackers@freebsd.org
Subject: Re: Multicast on PPP devices 
In-reply-to: Your message of "Mon, 21 Aug 95 10:26:29 PDT."
             <Pine.SUN.3.91.950821131558.10013K-100000@lupine.nsi.nasa.gov> 
Date: Mon, 21 Aug 1995 10:43:47 PDT
From: Bill Fenner <fenner@parc.xerox.com>
Message-Id: <95Aug21.104401pdt.177475@crevenia.parc.xerox.com>
Sender: hackers-owner@freebsd.org
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In message <Pine.SUN.3.91.950821131558.10013K-100000@lupine.nsi.nasa.gov> you w
rite:
>The ppp devices on 2.0.5 have the multicast bit set.  When I run mrouted 
>it dies with the errors:
>
>  Aug 21 13:14:40 sisyphus mrouted[8195]: warning - can't join group 
>    224.0.0.4 on interface 198.116.75.49: Can't assign requested address
>  Aug 21 13:14:40 sisyphus mrouted[8195]: warning - can't join group 
>    224.0.0.4 on interface 198.116.75.49: Can't assign requested address
>  Aug 21 13:14:40 sisyphus mrouted[8195]: setsockopt IP_MULTICAST_IF 
>    198.116.75.49: Can't assign requested address
>  Aug 21 13:14:40 sisyphus mrouted[8195]: setsockopt IP_MULTICAST_IF 
>    198.116.75.49: Can't assign requested address

Well, you appear to have numbered your PPP interfaces the same as your
ethernet interface.  The BSD multicast routing code requires each
interface to be in a different subnet.  (There's some chance that the
restriction can be relaxed to "have a different IP address", meaning
that you could use several addresses out of the same subnet, but each
interface definitely needs its own source address.)

Barring that, someone seems to have changed the INADDR_TO_IFP macro in
netinet/in_var.h to only search destination addresses, rather than local
addresses, on point-to-point interfaces.  This will cause mrouted no end
of grief.

I will check out the problem with disabling the phyint when it's down;
I would have thought that should work.  Unfortunately, unless you want
to renumber your ppp interfaces and change netinet/in_var.h, you won't
be able to use native multicast over your point-to-point interfaces.

  Bill