# Routing Between Two Subnets



## adz 2326 (Jan 12, 2006)

I hate to ask a question that may have been posed before, but my problem is not why something is not working, rather the why of how to overcome it.

At this point, i have a W2k3 Server connected to my LAN by a NIC on a class B network; the server connects to my Belkin router over a wireless network that is on a different subnet (Class C). Routing and Remote Access allows my clients on the Class C subnet to connect to the router on the other network to access the internet, but i cannot communicate to the B network from clients connected to the Belkin. 

I am assuming that as the belkin is used for the default gateway that because it does not have a route defined for the Class B network that the traffic is getting dropped? I cannot use the server as a router. How would i allow resources to be shared between the two networks? Would i have to install a router before the belkin or should i place the nics on the same subnet (I would rather avoid this)? Thanks for any help and i hope this is clear.


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## zx10guy (Mar 30, 2008)

Listing your IP address scheme for each subnet and interface would be helpful.


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## adz 2326 (Jan 12, 2006)

Hi and thanks for your reply,

This is the output from my server:

Ethernet adapter Local - 172.16.2.0 subnet:

Connection-specific DNS Suffix . :
DHCP Enabled. . . . . . . . . . . : No
IP Address. . . . . . . . . . . . : 172.16.2.250
Subnet Mask . . . . . . . . . . . : 255.255.255.0
Default Gateway . . . . . . . . . :

Ethernet adapter Wireless Network Connection:

Connection-specific DNS Suffix . :
DHCP Enabled. . . . . . . . . . . : No
IP Address. . . . . . . . . . . . : 192.168.5.15
Subnet Mask . . . . . . . . . . . : 255.255.255.0
Default Gateway . . . . . . . . . : 192.168.5.1
DNS Servers . . . . . . . . . . . : 192.168.5.1

So my addressing scheme is:

Class B Subnet:
Address: 172.16.2.0 -- Subnet: /24 (255.255.255.0)

Class C Subnet:
Address: 192.168.5.0 -- Subnet: /24 (255.255.255.0)
Belkin Router: 192.168.5.150

Hope this helps.


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## avisitor (Jul 13, 2008)

Assuming RRAS is correctly configured, all you would need to do is to place a static route on the gateways of both sides.

Since your gateway is a hardware router, pull out the manual and find out how to add the following route.

172.16.2.0 mask 255.255.255.0 192.168.5.15
192.168.5.0 mask 255.255.255.0 172.16.2.250


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## adz 2326 (Jan 12, 2006)

Im using the Belkin "Wireless G+ MIMO Modem Router" (http://catalog.belkin.com/IWCatProductPage.process?Product_Id=203415), i don't think its possible to set a static route on this. If i buy a new router that has this capability, that should work now then? Presumably RRAS should allow this setup?

Thanks.


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## zx10guy (Mar 30, 2008)

Is your Belkin router 192.168.5.150 or 192.168.5.1?

But the IP of the Belkin router is irrelevant to this problem. You can't get what you propose to work without turning your server into a router. The Belkin router which would be the default gateway for all the 192.168.5.0/24 clients does not have a router interface on the 172.16.2.0 network. The only device which has a physical path to it is your server. If you were to allow your server to be a router by enabling IP forwarding/routing, you would add a static route to your Belkin which states 172.16.2.0 255.255.255.0 192.168.5.15. You would then have to add a route to each client on the 172.16.2.0 network to have this route 192.168.5.0 255.255.255.0 172.16.2.250 or make the default gateway for every client to be 172.16.2.250. On the server, you don't need to add any static routes since both subnets are locally connected.


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## avisitor (Jul 13, 2008)

The OP has said that the server has RRAS enabled and properly configured.


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## zx10guy (Mar 30, 2008)

avisitor said:


> The OP has said that the server has RRAS enabled and properly configured.


Well, I'm confused on how this network is laid out. Because the OP stated this also in his post, "I cannot use the server as a router." If he has RRAS running, then the server is already acting as a router.


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## avisitor (Jul 13, 2008)

But the OP also says:



adz 2326 said:


> Routing and Remote Access allows my clients on the Class C subnet to connect to the router on the other network to access the internet


I think the best thing is just to wait for the OP to come back with clarification.


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## adz 2326 (Jan 12, 2006)

zx10guy - I can ping to the hosts on the belkin in the class C network and my hosts can connect to the internet connection through the server which is connected wirelessly to my belkin DFG. My problem is that i cannot connect the belkin hosts to my server, which i assume is because the belkin has no route to the network, and i cannot add one! 

My mistake i could've explained things a little better. Yes, the server is already effectively acting as a router running RRAS. What i was suggesting is that i connect the server to the belkin to act as a router, but i cannot move the server to where the belkin is, and i would have to leave it on permanently to allow internet access for others? 

Just to update - I have bought a new router that you can add static routes to, so i am hoping that it should work now. I would like to use XP Pro instead of windows server, but i am not sure whether it could route between the two nics when running ICS as well as RRAS might, should i leave the Server OS on? 

Thanks Again,
Adz 2326


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## adz 2326 (Jan 12, 2006)

Just to update,

I think it will be clearer if i show the layout of my network:

Internet
|
Belkin Router
192.168.5.1
|
PC's:
192.168.5.x dg 192.168.5.1
|
192.168.5.15 dg 192.168.5.1
RRAS router
172.16.2.250 dg blank
|
PC's:
172.16.2.x dg 172.16.2.250

My problem now is that despite having bought a new router and adding a route for the 172.16.2.250 network, i do not have connectivity between both of the networks. I think this is a problem with the RRAS configuration; when i make the wireless connection a public interface with NAT, i can ping from the 172.16.2.0 network to the 192.168.5.0 network, but not in return. With NAT disabled, i am able to ping the 172.16.2.250 interface from a client connected to the belkin. I have tried adding a static route to the server but that doesn't seem to have any effect, any help would be appreciated a lot.


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