Simply Joining 2 subnets.

  • Thread starter Thread starter fiddley
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fiddley

Hello routing gurus. I have (i think) a relatively simple problem.

Here's my situation: I run a small network behind an adsl line at
home. Got about 7 devices + a couple of laptops come and go on the
wireless.

My adsl provider has kindly offered to furnish me with a small block
of static IP addresses, but has asked that I minimise how many I ask
for.

So I am going to have some devices on routable IP addresses, and some
on a private IP range.

To test, I have started to move devices from the 192.168 Private IP
range, to the 10.0.0.0 private range. This is where it all goes tits
up. The 10... devices all see each other ok, and the 192.168.. devices
see each other. I configured the server's nic with addresses from both
ranges, and it can see both.

I would like all of the devices to be able to access the internet, and
each other.

I have figured that I need to configure RRAS to 'pass over' the
packets from the 10.0.0.0 to the 192.168 side, and this is where I'm
struggling to get it all straight in my head.

I have never used RRAS before, and the documentation is quite
confusing. Has anyone got any advice or tips?

Cheers,

Mark
 
assuming you have two NICs, this may help. quoted from
http://www.ChicagoTech.net
How to Configure Windows server to Be a Router
To setup Windows 2000/2003 as a router for a LAN, you need to two network
adapters. To enable LAN routing. go to Administrative Tools>Routing and
Remote Access>Action>Configure and Enable Routing and Remote Access, and
then complete the wizard. Right-click the server for which you want to
enable routing, and then click Properties>General>Router, check Local area
network (LAN) routing only, and then click OK.

--
For more and other information, go to http://www.ChicagoTech.net

Don't send e-mail or reply to me except you need consulting services.
Posting on MS newsgroup will benefit all readers and you may get more help.

Robert Lin, MS-MVP, MCSE & CNE
Networking, Internet, Routing, VPN, Anti-Virus, Tips & Troubleshooting on
http://www.ChicagoTech.net
This posting is provided "AS IS" with no warranties.
 
Routing between subnets is simple if there is only one router. eg

192.168.0.x dg 192.168.0.1
|
192.168.0.1 dg blank
router
10.0.0.1 dg blank
|
10.0.0.x dg 10.0.0.1

If there is another router (gateway) in one subnet which the clients use
as their default gateway, this method fails because the traffic never gets
to the internal router. So you have to add extra routing. eg

Internet
|
router
192.168.0.1
|
192.168.0.x dg 192.168.0.1
|
192.168.0.253 dg 192.168.0.1
router
10.0.0.1 dg blank
|
10.0.0.x dg 10.0.0.1

So that 10.0.0.x machines can get to the Internet and "see" the machines
on the 192.168.0 subnet, the Internet router needs to know how to reach the
10.0.0.0 subnet. It will work if you add a static route to the Internet
router to do this. eg

10.0.0.0 255.0.0.0 192.168.0.253
 
Bear in mind that this won't work if one subnet is using "real" public
IP addresses. Private IPs cannot be routed through the Internet without
proxy software or NAT. You would need to set up some sort of DMZ, with a
firewall between the public and private subnets.

Do you have a real reason to use registered public IP addresses? What
can't you do using your current setup?

If your router supports address mapping, you might be better off
allocating your public IPs to a pool on the router, then mapping addresses
to the private IPs of selected LAN machines (to make them visible from the
Internet).
 
Is there any documentation, Microsoft or otherwise, that discusses "how to
set up RRAS to be a simple LAN router between two subnets"? I'm trying to
set up a home network for MCSE training.
 
Probably not, except to tell you what the wizard does. As far as the
router goes, all you need to do is enable IP routing. In NT (without RRAS)
it was just a check box. In W2k without RRAS it is a registry setting. In
RRAS you enable IP routing.

Whether anything is routed or not depends on the default gateway
settings of the clients. To join two subnets (with no other gateway
involved) you simply set all clients to use the RRAS router as the default
gateway. eg

192.168.0.x dg 192.168.0.1
|
192.168.0.1 dg blank
RRAS
192.168.1.1 dg blank
|
192.168.1.x dg 192.168.1.1

Traffic for a machine in the same subnet is delivered directly (ie
using hardware addressing "on the wire"). Traffic for a machine in the other
subnet is sent to the router. The router then delivers it in the other
subnet (because it has an interface in that subnet and can deliver it
directly). The router simply forwards traffic from one subnet to the other.
 
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