How to configure a multi-homed Windows 2003 server to prefer a given connection for outbound access?
Posted on 2006-05-14
Good day everybody.
I rely on my Internet access, so I have two broadband connections: My main is DSL (1+Mbps over PPPoE from a DSL modem) and the backup is cable (128kbps over Ethernet from a DOCSIS cable modem). Each of the DSL and cable modems have a simple Netgear-series router that can provide access to the other machines on my network. I can get the whole network on one or the other by changing which is connected to the main switch. Since the machines on the network are all DHCP-configured, I just need them to release/renew after I manually change the router connected to the main switch, and they'll get a new address and gateway.
However, I have _one_ specific machine, a web server running Windows Server 2003, into which I added a second NIC and made it multi-homed. I configured it to accept HTTP from either external connection. That works great. However, when I use that machine to browse to the outside world (e.g. to download Windows Update patches), the traffic originating from the machine is being routed through the slower connection by default. I don't expect the server to know the difference, of course, since it sees both as 100Mbps up to each switch, and I didn't do anything special (yet) to tell it which one to prefer.
My question is: How can I configure the server so that it prefers to talk to the outside world on the connection that leads to the 3Mbps DSL modem's switch? I have a feeling I simply need to change the default gateway, but there doesn't appear to be any "make this the default gateway" option when I look at the TCP/IP properties for each connection. (I seem to remember there being precisely that kind of option - perhaps on an earlier version of Windows?)
"route print" confirms that the cable modem router (192.168.1.224) is the default gateway. How do I change that to be the DSL modem router (192.168.0.224) ? Here's the "route print" output from the server (which is itself 192.168.0.99 and 192.168.1.99):
Network Destination Netmask Gateway Interface Metric
0.0.0.0 0.0.0.0 192.168.0.224 192.168.0.99 20
0.0.0.0 0.0.0.0 192.168.1.224 192.168.1.99 20
127.0.0.0 255.0.0.0 127.0.0.1 127.0.0.1 1
192.168.0.0 255.255.255.0 192.168.0.99 192.168.0.99 20
192.168.0.99 255.255.255.255 127.0.0.1 127.0.0.1 20
192.168.0.255 255.255.255.255 192.168.0.99 192.168.0.99 20
192.168.1.0 255.255.255.0 192.168.1.99 192.168.1.99 20
192.168.1.99 255.255.255.255 127.0.0.1 127.0.0.1 20
192.168.1.255 255.255.255.255 192.168.1.99 192.168.1.99 20
220.127.116.11 240.0.0.0 192.168.0.99 192.168.0.99 20
18.104.22.168 240.0.0.0 192.168.1.99 192.168.1.99 20
255.255.255.255 255.255.255.255 192.168.0.99 192.168.0.99 1
255.255.255.255 255.255.255.255 192.168.1.99 192.168.1.99 1
Default Gateway: 192.168.1.224
I think I'm almost there but am missing the syntax, and would like some comfort with what I am doing before I try anything. How do I effect what I want? Thank you.