Yes, I have installed a few. It is called a 'one-arm router' or 'router
on a stick'. Cisco has some doc's on it, but I would doubt that the hub
is a hub. One-arm routers make use of vlans assigned to sub-interfaces.
Although I am sure by just assigning the sub-intf the proper segment and
the route statement, you could use a hub. Haven't tried that one yet,
but I will.  It is not a widely know configuration anymore. It was a
cheap way to install a router when interface were very expensive.

~Michael

-----Original Message-----
From: Frank H [mailto:[EMAIL PROTECTED]]
Sent: Wednesday, July 24, 2002 11:26 AM
To: [EMAIL PROTECTED]
Subject: Proper network design? [7:49536]


Proper network design?

I have a few questions for the group that maybe someone can answer. From
my
studies when I got CCNA certified, I understood that different networks
were
ALWAYS separated by a router. At my company we have this equipment that
was
purchased several months ago that acts as a digital cellular network. It
was
set up and was able to operate, but only in a limited way. Basically,
this
is the setup - the digital cellular network was on the 192.168.2.0
subnet
(subnet mask 255.255.255.0). The company development LAN was on the
192.168.0.0 subnet (subnet mask 255.255.255.0). The two small networks
(less
than 10 hosts in each subnet) were all tied together at a 24 port hub.
The
gateway to the Internet was through a Linux box. The digital cellular
network was basically a box (with IP address 192.168.0.100) that passed
packets to network 192.168.2.0 through a low power transmitter to the
cellular hosts in the 192.168.2.0 subnet. With this setup, only one
desktop
host on the 192.168.0.0 network could communicate to the 192.168.2.0
cellular network (desktop host 192.168.0.20). The problem of only one
desktop host in the 192.168.0.0 network being able to communicate with
the
192.168.2.0 network was solved by replacing the Linux box with a Cisco
2514
router (with two ethernet interfaces). The configuration for the router
was
exactly the same as the Linux box except for one small addition. The
following line was added as a static route:

ip route 192.168.2.0 255.255.255.0 192.168.0.100

Now let me ask you, have you ever seen a router that gets a packet on
one
interface pass it right back out the SAME interface back to another host
on
that same network? Our setup basically ties two DIFFERENT class C
subnets
together through a hub and the Cisco router makes it all work perfectly.
This doesn't sound like standard network design as I've seen it
described in
any text so far. I'll describe it a little more for clarity. If i'm on a
desktop PC (IP address 192.168.0.20) and ping IP address 192.168.2.2,
windows will send that packet to the default gateway (configured as
192.168.0.1 in windows network applet - which is the Cisco router) since
it
lies in a different network (since the subnet mask is 255.255.255.0).
The
Cisco router receives this packet destined for the 192.168.2.0 network
and
since it matches it with the above static route, sends it back out the
same
interface it came in on, back to another host (192.168.0.100 - the
cellular
transmitter box) out to the cellular host (192.168.2.2). This is the way
the
cellular network equipment manufacturer intended it to work. The setup
works, but it sounds really weird and nonstandard. Has anyone else
encountered such a setup or something similar before? Is this a kind of
network design that is done often? Doesn't a router normally always
route
packets from one interface to another?

Thanks in advance for your responses.

Frank




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