Date: Thu, 22 Aug 1996 19:22:42 -0500 (CDT) From: Joe Greco <jgreco@brasil.moneng.mei.com> To: vovik@cmr.kiev.ua (Vladimir Jakovenko) Cc: freebsd-hackers@freebsd.org Subject: Re: IP over IP Message-ID: <199608230022.TAA25515@brasil.moneng.mei.com> In-Reply-To: <199608220442.EAA13472@cmr.kiev.ua> from "Vladimir Jakovenko" at Aug 22, 96 07:42:41 am
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> Hi, all!
>
> Sorry for long posting, but it seems we really have a problem here.
>
> Some time ago our University was given access to Internet. We have
> only 8+16 IP adress from ISP. Our network is happened to look like
> it is shown on (simplified) figure below.
Why not configure a second interface (say, a tun0 device or something) as a
dummy interface?
> Internet
> ^ 2 Mb/s
> 10 Mb/s |
> ---o------------------o------ |
> +-----+------+ +-------+-------+ |
> | oberon | | r2d2 | |
> | FBSD-2.1.5 | | CISCO 2511 +------+
> | | | |
> [I] +-+----------+ +---------------+ InterNet
> |
> -------|-----------------------------------------------------------
> [II] | IntraNet
> |
> |
> | +---------------+
> +------+-----+ | cad |
> | inferno + ----... | FBSD-2.1.5 |
> | Novel 3.12 | | |
> | +-----... +-------+-------+
> +------+-----+ |
> 10.0.0.9| |
> | +---------------+ +-------+-------+
> | | space | | ee |
> | | FBSD-2.1.5 | | FBSD-2.1.5 |
> | | | | |
> | +-------+-------+ +-------+-------+
> +---------------o------------------------o-----
> 10.0.0.10 10.0.0.11
It is not clear if oberon has a direct connection to "space" and "ee", or if
"inferno" sits between them. Let me redraw this for you.
Okay, so you have 8 addresses on the 10mbps. I'm assuming you do not want
to burn them.
10.0.0.? network
|-----------------------------------------------------|
| .1 | .2 | .3 | .4
-------- -------- -------- --------
|oberon| |space | |ee | |infern|
-------- -------- -------- --------
.3 | | .1 | |
<---------- | 10.0.1.?
to r2d2 |----------|
network W.X.Y.? | .2
--------
|mybox |
--------
You have a "backbone" that is 10.0.0.X, and various subnets on your
routers.. I have shown ONE for simplicity, 10.0.1.X. You have a node,
10.0.1.2, which is connected on that network, and you want it on the
Internet.
So youu want "mybox" to be on the Internet as A.B.C.D, but it has an
address of 10.0.1.2.
First, r2d2 has to route all 16 addresses to oberon's address, W.X.Y.3
route add -net A.B.C.0 -netmask 0xfffffff0 W.X.Y.3
Now, oberon can control assignments by routing individual IP's to various
routers. Route "A.B.C.D" to "space".
route add -host A.B.C.D 10.0.0.2
Now "space" needs to route it to "mybox".
route add -host A.B.C.D 10.0.1.2
Now "mybox" gets packets destined for A.B.C.D. Configure "mybox" to accept
them. You may be able to do it with an alias Ethernet address (dunno).
ifconfig ed0 alias A.B.C.D netmask 0xffffffff
maybe, or create a dummy tun device or something.. I don't know what the
"best" way to do it is, there are several ways though and I use a number
of them.
Remember that you can do this multiple times for multiple nodes. It is
SIMPLY a routing problem. Easy beans. And best of all - unlike Ethernet
you do not waste the first and last addresses on your A.B.C.? block of 16
addresses.
... JG
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