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What is the best way to have Microsoft load balancing servers on a 5505?

Because the nature of MS load balancing is to use the sampel virtual MAC address for all the servers in the load balance cluster, the switch floods packets to the virtual MAC address to ALL ports of the switch. We have a 5505 with several dozen unix hosts on it along with 5 MS servers that are in load balancing mode. Since the traffice destined to the MS servers is flooded to all the ports, it is affecting some of the unix hosts.

Has anyone run into this scenario? Is the only way to make this more stable is to move the 5 MS load balanced servers off onto a new switch with a new subnet? (I don't want to have multiple vlans on the same 5505).

New Member

Re: What is the best way to have Microsoft load balancing server

You describe the default configuration for Network Load Balancing. There is an alternative, where the Windows registry value masksourceMAC is changed such that the NICs use normal MAC addresses. To make NLB work in this scenario you must use a hub (repeater) to ensure that all NLB ports 'hear' the traffic. This is the configuration we use, the switch flooding gets a bit much ...

See the Microsoft article KB193602 available at;en-us;193602


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