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From: sklower@oboe.CS.Berkeley.EDU (Keith Sklower)
Newsgroups: comp.unix.bsd.freebsd.misc
Subject: Re: TCP/IP & Routing & netmasks. :-)
Date: 26 Jan 1996 00:49:38 GMT
Organization: University of California, Berkeley
Lines: 66
Message-ID: <4e98f2$o7j@agate.berkeley.edu>
References: <4e83av$sn@turtle.apana.org.au>
NNTP-Posting-Host: oboe.cs.berkeley.edu
In article <4e83av$sn@turtle.apana.org.au>,
Robert Nagy <nagy@turtle.apana.org.au> wrote:
}
}Here is what I need to do..
}
}
} hosts on this net hosts on this net
} | | | | | | | | |
} ---------------- -------------------
} 203.9.159.1 203.9.159.128
} ---------------- -------------------
} \ /
} \ /
} ---------------------
} our new isp
} let's say
} the router is
} 130.131.9.1
} ---------------------
Uh, is the "hosts on this net" above 203.9.159.1 supposed
to be indicating point-to-point links or are they coming out
of an ethernet? I'll attempt to answer this based on the code
in 4.4Lite; I haven't heard that FreeBSD substantially changes it.
}Is the netmask on both .1 and .128 supposed to be 255.255.255.128 ?
Yes, but you probably want to make 203.9.159.128 to be 203.9.159.129
instead, otherwise you have a host with the same address as the subnet
which is probably going to cause problems . . .
}does this mean that I simply point the routes by
}route add -net 203.9.159.127 130.131.9.1 on the .1 system and
}route add -net 203.9.159.0 130.131.9.1 on the .128 system?
Actually, you can just say
route add default 130.131.9.1
on either system, if you tell your new isp to statically configure things
so things in the lower half go to to .1 and things in the upper half go
to .129.
If you wanted to add a (redundant) route explicitly mentioning the other
net the syntax would be
route add -net 209.9.159.128 -netmask 255.255.255.128 120.131.9.1
on the .1 system and
route add -net 209.9.159.0 -netmask 255.255.255.128 120.131.9.1
on the .129 system.
It wouldn't be hard to change the route command to grok things like
route add -net 209.9.159.128/25 130.131.9.1
but that's not how the way 4.4Lite version does it.
If the "hosts on this net" are going out a single ethernet
you must say
ifconfig we0 203.9.159.1 netmask 255.255.255.128
and if they are ppp links, you better set the netmask as tight as
possible.