2008 Networking Issue

[wykd]

Below is the route table on a 2008 Server with one IP on the NIC, 192.168.1.50.

My issue is that I'm adding a secondary IP, 192.168.1.51, and all of the route information is switched over to that new IP. Even if I set *.51 as the primary IP on the NIC, and add *.50 as a secondary, it moves everything in the route table to *.51. This causes some problems because we have websites running on *.50. Is this normal behavior, and if not, what can I do to fix it?

Before:
Network Destination Netmask Gateway Interface Metric
0.0.0.0 0.0.0.0 192.168.1.1 192.168.1.50 266
192.168.1.0 255.255.255.0 On-link 192.168.1.50 266
192.168.1.50 255.255.255.255 On-link 192.168.1.50 266
192.168.1.255 255.255.255.255 On-link 192.168.1.50 266
127.0.0.0 255.0.0.0 On-link 127.0.0.1 306
127.0.0.1 255.255.255.255 On-link 127.0.0.1 306
127.255.255.255 255.255.255.255 On-link 127.0.0.1 306
224.0.0.0 240.0.0.0 On-link 127.0.0.1 306
224.0.0.0 240.0.0.0 On-link 192.168.1.50 266
255.255.255.255 255.255.255.255 On-link 127.0.0.1 306
255.255.255.255 255.255.255.255 On-link 192.168.1.50 266

After:
Network Destination Netmask Gateway Interface Metric
0.0.0.0 0.0.0.0 192.168.1.1 192.168.1.51 266
192.168.1.0 255.255.255.0 On-link 192.168.1.51 266
192.168.1.51 255.255.255.255 On-link 192.168.1.51 266
192.168.1.255 255.255.255.255 On-link 192.168.1.51 266
127.0.0.0 255.0.0.0 On-link 127.0.0.1 306
127.0.0.1 255.255.255.255 On-link 127.0.0.1 306
127.255.255.255 255.255.255.255 On-link 127.0.0.1 306
224.0.0.0 240.0.0.0 On-link 127.0.0.1 306
224.0.0.0 240.0.0.0 On-link 192.168.1.51 266
255.255.255.255 255.255.255.255 On-link 127.0.0.1 306
255.255.255.255 255.255.255.255 On-link 192.168.1.51 266

 

[necrophobic]

Try adding a persistent route?

 

[wykd]

I'm not sure that a persistent route would fix this issue. It changes all of the routes when the secondary IP is added. I wasn't able to duplicate this on another 2008 box so something is going on with this specific box.

 

[just2cool]

I'm not too familiar with Windows routing, but I'm assuming that, for equal cost routes, it chooses the highest IP. This is commonly done on Cisco routers when there's a tie.

If you set a secondary IP below .50, does it still have .50 in its routing table?

 

[wykd]

Anyone else have any ideas? I've seen various posts around google about how Windows 2008 got rid of the primary/secondary IP concept. I confirmed that giving the box a higher IP doesn't change the routes. Anyone have any understanding of how Windows 2008 builds the route table?