I am running the Microsoft Network Load Balancer on a webfarm with 4 servers. The nodes are configured using multicast and I verified they can be accessed both inside and outside the firewall (Cisco PIX 515 running 6.3(3)). The issue I am having is that when I test the failover by shutting down one of the servers I notice that inside the firewall I am still able to access the webfarm but outside I get a "page cannot be displayed". I narrowed it down to notice that server #2 is the only one the firewall sees. If that server is down, I am unable to ping the virtual IP of the webfarm, but inside the firewall I am still able to access the webpage when server #2 is down. The only only ports I am forwarding through the firewall are ports 80 and 443, are they any additional ports that need to be opened for the multicasting to work correctly?
Any suggestions are appreicated.