One Web Server Two NIC with Two Different Wan Network

networkingnicwide-area-network

I got one Web Server (IIS), MS windows server 2012 with two nic and want to connect this two nic to different ISP with different public ips address. I got totally seperate set of infrastructure of this two different wan network.

For eg.

Nic 1 is with 192.168.168.110 Subnet 255.255.255.0 and default Gateway 192.168.168.168 with public ip address 113.xx.xx.xxx and web site name us.example.com

Nic 2 is with 192.168.0.160 Subnet 255.255.255.0 and default Gateway 192.168.0.1 with public ip address 203.xx.xx.xxx and web site name uk.example.com

The purpose of using two different wan as redudancy and also latency issue for different region.

Is their any issue or anything i should take note for this setup? How the server know which NIC they should use when they browsing. As i research i need to remove one of the NIC's Default gateway to let the another one to be the main for browsing.

Will removing one of the NIC's default gateway will have any effect to its capability of accesssing from outside?

Best Answer

Windows, and most OSes only "use" one default gateway at a time. It doesn't distinguish on a per NIC basis. If you have two default gateways in your routing table on the server (the default gateway in the NIC screen becomes a default route (0.0.0.0) in the routing table) then the one with the lowest metric will be used. You can use 'route print' to see that the two 0.0.0.0 entries have different metrics.

So, if you remove the default gateway from one of the NICs that has incoming traffic, then that traffic will be sent back out of the default gateway in the routing table (the default gateway on the other NIC) and dropped on the other side ( as unsolicited traffic ). This happens because there are no routes to the destination of the incoming traffic! You could set up local routing to send specific traffic to required interface, but you'd need to know the specific network ranges you wanted to deal with.

If you need redundancy for two ISPs, then you should have that redundancy set up on an actual router, or a switch that can handle it.

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