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In my company, We have two differnet networks, from two different ISP'S and we have two NIC on one windows server 2003, but we are unable to connect both the network together and ping both networks simultaneously. I would like to know, what should we the subnet mask and default gateway on both the network card and ipaddress.

Please help me out.

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marked as duplicate by Jacob, Ward, mdpc, Falcon Momot, rnxrx Jun 17 '13 at 6:34

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3 Answers 3

In general, for each ISP you will (or should) have a separate router. These routers will each provide a DHCP service where they assign IP-addresses to computers connected to them.

Each router should be configured to have a separate pool of addresses in it's DHCP pool. For example one router might have a pool of 192.168.1.2 through 192.168.1.254 with a subnet mask of 255.255.255.0. In that case ensure the other router is using a separate range and a separate subnet such as 192.168.2.2 through 192.168.2.254 with a subnet mask of 255.255.255.0.

If this is done, the computer should pick up the correct addresses and have no local routing conflict. I am unsure what algorithm Windows Server 2003 applies to routing to other networks when the gateway routers have the same routing cost (e.g. hop-count). You will probably find that one ISP is favoured but if that ISP is down I would expect that the operating system will eventually mark the route down and redirect traffic to the other ISP. This is speculation on my part.

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This is possible to do in Windows, however you don't give a lot of detail about your setup, that said, I highly recommend a firewall between your server and the ISP. Many mid level firewalls support multiple ISP links and provide automatic failover or load balancing.

You need to configure each NIC for the network provided on the attached router. The subnet mask should be the same as provided by the ISP. You can setup multiple default gateways in the TCP/IP settings and set the metrics so that one takes precedence over the other. My assumption is that you want some sort of failover setup where the server will use one network primarily and fail over to the other if the first one fails.

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You may want to look at a load-balancing router. Both of your Internet services will connect to this device. As far as the internal network is concerned, there is only one path to the Internet - the router will take care of picking the best route.

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