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Date:      Thu, 19 Aug 1999 13:01:26 -0700
From:      George Chung <gchung@microsoft.com>
To:        George Chung <gchung@microsoft.com>, "'freebsd-net@freebsd.org'" <freebsd-net@freebsd.org>
Subject:   RE: PLEASE HELP: mcast weirdness on private network
Message-ID:  <C35556591D34D111BB5600805F1961B910ECC11E@RED-MSG-47>

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issue resolved. the bsd boxes incorrectly specified a gateway.

-----Original Message-----
From: George Chung [mailto:gchung@microsoft.com]
Sent: Thursday, August 19, 1999 11:49 AM
To: George Chung; 'freebsd-net@freebsd.org'
Subject: RE: PLEASE HELP: mcast weirdness on private network


BTW, there is no problem when using the all-hosts address 224.0.0.1.

>  -----Original Message-----
> From: 	George Chung  
> Sent:	Thursday, August 19, 1999 10:25 AM
> To:	'freebsd-net@freebsd.org'
> Subject:	PLEASE HELP: mcast weirdness on private network
> 
> Hi Gurus:
> On a "normal" network (routers, connected to the inet), an app on NT4 and
> FreeBSD 3.2 can join an mcast group (225.0.0.1) and send/receive messages
> to each other on that address.
> 
> However, when I move the binaries to a private network (no router) with
> NT4 and FreeBSD:
> An NT box is able to communicate bidrectionally with another NT box.
> The FreeBSD boxes are able to communicate bidrectionally with each other.
> The FreeBSD boxes are able to receive mcast packets from the NT boxes.
> BUT, the NT boxes aren't able to pick up mcast packets from FreeBSD!!
> 
> Here's the network:
> m1 10.100.100.100 FreeBSD dual-homed (the 2nd interface is unconfigured).
> m2 10.100.100.102 FreeBSD dual-homed (the 2nd interface is unconfigured).
> m3 10.100.100.200 NT4
> m4 10.100.100.202 W2K
> 
> I had to tweak the FreeBSD boxes to get them to even work by adding a
> route for 225.0.0.1 (otherwise, I got a EHOSTUNREACH error when pinging
> 225.0.0.1). I am not sure I did this correctly. Here's my command:
> 
> route add -net 225.0.0.1 -netmask 0xf0000000 -interface 10.100.100.100
> 
> The mcast code on FreeBSD does the following above and beyond the default
> (because they are multihomed):
> in the call to join the group, I specify the specific interface to receive
> on.
> I also call setsockopt to set the outgoing interface on mcast sends.
> 
> I am scratching my head. The only thing I can think of is that Windows NT
> is filtering out IP packets whose source IP address it doesn't "know". But
> the only way I know how to do that for UDP sockets is to explicitly
> connect it to an endpoint. Any help would be greatly appreciated.
> 
> Thanks,
> George
> 


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