I have two physical servers running Win2008 Enterprise, with 4 virtual machines each running on Hyper-V. I created a cluster using one of the virtual machines in each server, using Network Load Balancing under Windows 2003, using the multicast option.

The cluster nodes are converging correctly, I can ping the virtual IP from any of my machines in the datacenter (they share a single rack and a switch) but can't ping it from machines outside this switch, making the cluster invisible to the public internet.

All server use public IPs from the same VLAN, gateway and subnet mask. Is there anything else I need to configure on the machines, on the switch, or even in the datacenter router?

  • I agree that this is most likely either a router or firewall issue. You might want to consider adding the "Networking" and "Firewall" tags to your question. – KevinH Jun 2 '09 at 18:15

The only thing I can think of is that you have a zealous firewall configured on the router which is locking down incoming traffic to the specific IPs of the servers you already have. If so you would need to add the VIP into the router firewall rules.

You state that the VIP is on the same VLAN as your servers (at least, I think that is what you are saying) so... you appear to have configured everything appropriately if the cluster works internally to the VLAN.


Off the hip I'd guess the cluster IP is configured such that the route and netmask preclude it working through a router.


Perhaps your firewall (datacenter router) does not permit IP spoofing? If memory serves, Cisco ASA firewalls are amongst those who don't allow this.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.