Date: Thu, 27 Feb 1997 09:30:10 -0700 (MST) From: Softweyr LLC <softweyr@xmission.com> To: dg@root.com Cc: questions@freebsd.org Subject: Re: forwarding broadcast packets between interfaces Message-ID: <199702271630.JAA17649@xmission.xmission.com> In-Reply-To: <199702271404.GAA04752@root.com> from "David Greenman" at Feb 27, 97 06:04:34 am
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David Greenman recently enlightened us thusly:
> Broadcasts have nothing to do with UDP packets other than a UDP packet,
> like any other IP packet, may or may not be sent to a broadcast address.
> It is true that packets sent to the broadcast address are not routed through
> the gateway, and aside from creative mis-configuration, there isn't any way
> you can get the gateway to pass them through, either.
Exactly right; the same is true of multicasts. There are situations in
which you want to route multicasts, or even broadcasts, between two
networks, but they are few and far between. About the only router
maker that really understands this is Cisco. You could probably fake
it to some extent with a FreeBSD router with some creative route table
manipulations, but chances are pretty good you'll just screw up routing
to the point where it doesn't work at all.
In general, if you want to share broadcasts or multicasts between two
networks, you need bridges rather than routers. The idea of a
broadcast packet being literally sent to every computer attached to the
internet gives me the creeping willies. What an abuse!
--
"Where am I, and what am I doing in this handbasket?"
Wes Peters Softweyr LLC
http://www.xmission.com/~softweyr softweyr@xmission.com
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