I am having the exact same problem to the issue described here:
Basically, we have set up MS NLB for two Windows 2003 webservers on a 192.168.8.x range. The server addresses are 8.2 and 8.3, and the NLB address is 8.4. We are using multicast, as the servers must be able to communicate with one another. I have a Cisco Catalyst 3550 L3 switch, which routes traffic using a single VLAN set up with a primary .8.x address and secondary addresses for .10.x and .12.x. I can ping both servers from any of the above subnets (because their gateway is the L3 switch), but I can only ping the NLB address from the 8.x subnet. I need this to communicate across all of the subnets on the above VLAN. The solution given in the above thread was to put the NLB in a separate VLAN. Could someone explain what he meant specifically, or how I can solve this issue with the equipment I have? Do create another VLAN on the L3 switch with a different subnet (say, 192.168.20.1) and set the NLB address to 20.x? Any help would be much appreciated, and specific commands or instructions would be a bonus.
Thanks in advance.