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

Your department has to configure the correct router settings on their router.

tripodkid said:

Hi there!

I would really appreciate some help using Windows 7 to route some IPs.

I need to use and move a wireless device, that is a part of a larger system, from one area of a large establishment to another and back again using two different networks. The device has a static IP of xxx.xxx.200.119. This address can't change or be dynamically assigned.

In the main area of a large building the device has to communicate with IPs xxx.xxx.200.100 to xxx.xxx.100.118. This is the only wireless device and it connects to the other IPs through an access point, that's not a router, with a wired IP of xxx.xxx.200.113 and the SSID is Room1. The subnet mask is 255.255.255.0 and the gateway is xxx.xxx.200.1.

The device can and will be re-registered, using a docking station, to operate in a completely different area of the building. In the second area it has to communicate with IPs xxx.xxx.200.119, .120 and .121. Here the access point has a wired IP of xxx.xxx.200.120 and SSID of Room2, again it is not a router. When the device is re-registered only the SSID of the access point, to which it needs to connect, is changed.

xxx.xxx.200.119 is a laptop which is connected to the second AP with IP of .120 . All of the above functionality is configured and works fine but here is my problem...

In the second area of the building the IP address that the IT dept has given me is xxx.xxx.242.211. Subnet mask is still 255.255.255.0 and the gateway is, you guessed it, xxx.xxx.242.1. So I figured no problem I'll just assign both the xxx.xxx.200.119 and xxx.xxx.242.211 to the NIC in the laptop. But this does not work because the laptop then thinks that the IP's xxx.xxx.200.100 to .118 are local and therefore does not use a gateway so I loose communication with them. Therefore, what I think I need to do is find a way to route those IP's through the .242.1 gateway.

Sorry for the long winded description!!! Many thanks in advance for any help given!!!

It would seem that you need variable subnet masks in order to complete this action. Are you able to produce a network topology to better understand your configuration? What subnet masks are you currently using?

Josh

Unless you can change it you can't set the device (xxx.xxx.200.119) to communicate with xxx.xxx.200.100 to xxx.xxx.200.118 unless you set a custom subnet mask.

255.255.255.0 means the computer will check the IP address it wants to communicate to with the 255 octet. If it is a match then it will move to the next. If that is a match then it will move to the next octet. If all 3 octets are the same then the devices IP address will send out a broadcast since it thinks the device is on its LAN. 0 = Host

A variable length subnet mask will tell the machine that xxx.xxx.200.100 to 118 is not on its LAN therfore it will contact it's default gateway to route the packets to its appropriate destination.

Are you using public or private IP addresses for these devices? In other words is the first octet one of the following?

192.168.xxx.xxx
10.xxx.xxx.xxx
172.16.xxx.xxx - 172.31.xxx.xxx
169.254.xxx.xxx

Josh

In addition if you do change the subnet mask then you will need to change it on all routers and devices which need access to xxx.xxx.200.100 to xxx.xxx.200.118

tripodkid said:

Unfortunately I have no control over the network or the IT dept. All subnet masks are 255.255.255.0

How will you find the other subnet? Answer: through a router. Tell me what router knows where to find it (or kknows the route to find it)

Kaktussoft said:

tripodkid said:

Unfortunately I have no control over the network or the IT dept. All subnet masks are 255.255.255.0

How will you find the other subnet? Answer: through a router. Tell me what router knows where to find it (or kknows the route to find it)

I think the issue is that the computer itself isn't contacting the router to find it since the subnet mask tells the computer that it is on it's LAN therefore it sends out a broadcast to try and find it which of course is failing.

Your computer has an ip address and defaultgateway... either by dhcp or static. All ip addresses in subnet are found directly. Other addresses are transfered to default gateway. Unless you define static routes