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Archive for the ‘NetworkLoadBalancing’ Category

Configure Windows Network Load Balance (NLB)

Posted by Brajesh Panda on December 31, 2009

People used to keep me asking about “how to configure NLB for web servers?”. I will be releasing my step by step guide for the same. But for time being you can refer to a very good article over here. (

Here are some merits & demerits of Windows network load balancer & hardware load balancer!

Point 1:

WNLB:  broadcast the request to all the servers in the cluster and one of the servers says I receive it.

So Server must be connected to a network switch which allows Broadcast (at least in the same subnet) like Layer 2 Switches.

So if your switch is a layer 3 switch your cluster will never work. To make this work issue you need to create a Layer 2 VLAN in your Layer 3 switch.

HLB: No worries like this in

 Point 2:

WNLB: is not application aware. Means even if application is already dead but server is live, it will still send packets to the server.

HLB: You can configure application verification (by teleneting to 80/443 port etc) to see if application is live or not. If application dead it will assume server is dead.

Point 3:

WNLB:  Network Card GUID issue. If you deploy virtual machine or ghost copies some time you may end up with same network card guid in registry & it create conflict in windows load balancing technique.

HLB:  No issues because virtual is bonded to network IP

Point 4:

WNLB: No Web Acceleration

HLB: Web Acceleration by Caching

Point 5:

WNLB: No SSL or other encryption offloading

HLB:  SSL Offloading  & other firewall/security level configuration can possible

Another Good Link:


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