Multiple IPs on 1 NIC-How do I forse them to use the same gateway?

Correct but only if the computer deems that the destination IP is not on its LAN. This would be defined by the subnet mask. Static routes are set on the router/gateway and from the machines perspective it has no knowledge of the routers routing table. If the static route has the subnet mask of 255.255.255.0 or wildcard of 0.0.0.255 then the packet will simply be returned to the LAN at which it came since destination IP address will appear to the router as the same subnet as the source IP address.

tripodkid said:

Unfortunately, as I mentioned earlier, I have no control over the network or the IT dept so making changes to routers etc is just not going to happen. That is why I am looking for a way to manually configure the routing of those IPs within W7 on the laptop. I did try using a class B 255.255.0.0 subnet mask but that did not work.

Thanks!

255.255.0.0 will not work if xxx.xxx is the same across all subnets. When I mean variable length subnet in your case I mean a subnet like the following: 255.255.255.145

THIS IS AN EXAMPLE

You need to have access to the router and other devices on the network in order to apply a new subnet mask. Have contacted your IT department as to what you wish to accomplish? If they knew then they would understand that the subnet mask of 255.255.255.0 will not work



Josh

tripodkid said:

Unfortunately, as I mentioned earlier, I have no control over the network or the IT dept so making changes to routers etc is just not going to happen. That is why I am looking for a way to manually configure the routing of those IPs within W7 on the laptop. I did try using a class B 255.255.0.0 subnet mask but that did not work.

Thanks!

If you change subnet to 255.255.0.0 ... it thinks ven more ip address are locally (reachable without a router).

If you keep subnet 255.255.0.0 it's fine. All local ip's are found. All other addresses go to defualt gateway.

What router can you reach, and what same router can reach the ip addrress you want?
It's all a routing problem!

xxx.xxx.200.y can access xxx.xxx.200.z directly (assuming subnet = 255.255.255.0 and all connected to same switch)
Other addresses got to default gateway, or through another router if some sort of static routing is defined.

The defualt gateway SHOULD know all other subnets, so should find all other ip adresses.

Normally only the default gateway should be defined. Also the ip address and subnet (to find local ip addresses). Normally done using dhcp.

This issue is the subnet mask applied. You could change the subnet mask on your NIC but unless the router has the same subnet mask the routing will fail. The only way I can see this being solved without access to the router would be to change the address of xxx.xxx.200.120 and xxx.xxx.200.121 to the following:

xxx.xxx.242.120 & xxx.xxx.242.121

Josh

You want to acceess xxx.xxx.200.a from xxx.xxx.242.y (subnet 255.255.255.0). Do you know one router that you can access and that can access xxx.xxx.200.a ?

Kaktussoft said:

The defualt gateway SHOULD know all other subnets, so should find all other ip adresses.

Only if defined by an Administrator. For example I have a route in my routing table with a subnet mask of 255.255.255.252 also known as /30. This was only known because I statically assigned the ip address and subnet mask to that interface. Even if the OP changed the subnet mask on their NIC the router would not know where to route it the packets to since the subnet mask set for that interface will not be the same as the one set on the NIC.





If you don't have access to the router then all I can suggest is to change the IP address of the two local .200 machines as listed in my previous post I wish there was another way but this is how TCP/IP works

Hope This Helps,
Josh :)

Both source and destination (xxx.xxx.200.y and xxx.xxx.242.z) (both subnet 255.255.255.0) are on another subnet. So it MUST be routed through a router!