Date: Mon, 6 Oct 1997 17:23:45 -0700 From: "alex huppenthal" <alex@comsys.com> To: "Don Lewis" <Don.Lewis@tsc.tdk.com>, "Daniel O'Callaghan" <danny@panda.hilink.com.au>, "chrw" <shredder@hack.babel.dk> Cc: <freebsd-isp@FreeBSD.ORG> Subject: Re: routing between networks Message-ID: <01bcd2b7$4601c320$3a31cacc@neisse.comsys.com>
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An approach we've used with success is to add another Class C address, by
way of
an alias to your router.
We have non-contiguous IP numbers routed from our site in Aspen to the
Internet.
I setup our Cisco to reponse to both Class C's on its only ethernet port.
If your router is a FreeBSD system, you might consider adding your second
IP Class C (194.19.2) by way of alias. It works.
Alternatively, add another NIC to your router, set its IP to your new Class
C addr, and
BSD should route between these networks with no further configuration.
Hope this helps.
-----Original Message-----
From: Don Lewis <Don.Lewis@tsc.tdk.com>
To: Daniel O'Callaghan <danny@panda.hilink.com.au>; chrw
<shredder@hack.babel.dk>
Cc: freebsd-isp@FreeBSD.ORG <freebsd-isp@FreeBSD.ORG>
Date: Monday, October 06, 1997 4:28 PM
Subject: Re: routing between networks
>On Oct 6, 10:41pm, "Daniel O'Callaghan" wrote:
>} Subject: Re: routing between networks
>}
>} On Mon, 6 Oct 1997, chrw wrote:
>}
>} > Hello, I have a small question to ask. I do not fully understand how
>} > routing between 2 logical networks works. Lets say I got net 194.19.1,
with
>} > default gateway and router to the internet at 194.19.1.1. Now, I want
to
>} > add another C net, 194.19.2 with the same gateway as net .1. This new
net
>} > cannot see the other net, so I need to setup a box to route between
these
>} > 2 nets.. right?
>}
>} Yes.
>
>Not necessarily. If you have two (or some power of two) adjacent network
>numbers that start on a power of two boundary, and if all the boxes on
>the network understand classless routing ({Free,Open,Net}BSD should all
>qualify, as does Solaris 2.6, and I imagine that Linux probably does
>as well), then the best solution is to just change the network mask to
>do supernetting. In this case, you would just need to do:
> ifconfig interface 194.19.{1,2}.xxx netmask 255.255.254.0
>
>The next best solution is to use the route command. On your 194.19.1.*
>hosts, you would need to do:
> route add net 194.19.2.0 address-of-this-host-on-194.19.2 metric 0
>and on your 194.19.2.* hosts, you would need to do:
> route add net 194.19.1.0 address-of-this-host-on-194.19.1 metric 0
>I've never attempted this, but I think most TCP stacks support this. In
>this scheme I don't know if your 194.19.2.* hosts can use a 194.19.1.1 as
>a default gateway, so you may need to create an interface alias on the
>194.19.2.* network for it and point the default route to that address.
>
>The advantage of either of these schemes is that each host on the
>network can communicate directly with any other host on the network.
>If you route between the networks, any packets sent from one logical
>network number to another will traverse the physical network twice.
>
>} > Do I need to setup a box with 2 NICS, one for each net? The
>}
>} Yes.
>
>No.
>
>} > way I prefer it, is to route between the nets, but stay with a single
NIC.
>}
>} You may *think* you prefer it, but if you do it that way you'll find that
>} 1 NIC per network is best.
>
>Any particular reason that you think 2 NICs are better than 1? I can
>think of several reasons why 1 is better:
>
> Less hardware to purchase (NICs, hub ports or transceivers, cables)
>
> Fewer cables to hook up
>
> Fewer slots used
>
> Better performance (with two NICs, if both decide to transmit at
> the same time, you'll get a collision and both will back off
> for some random amount of time, but with one NIC the packets will
> be sent out back to back)
>
> --- Truck
>
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