MsExchange Blog Spot Telnet25

October 3, 2012

CAS Array HLB or NLB

Filed under: General — telnet25 @ 2:43 pm

If you are planning or implementing  CAS Array and wondering what are the options for load balance your CAS servers here is quick reference to remember.


  • HLB ( hardware load balance ) solution, This is what is being recommended.
  • SLB ( Software load balance) solution, This is also recommended.
  • Windows NLB ( network load balancing) This is no longer recommended

If you have not see Rose Smith video presentation do not miss it , How Outlook connects to Exchange 2010 Client Access Server

The main reason why HLB & SLB  are recommended , these solutions provides ā€œ Application awarenessā€ and also managing CAS servers behind these type of deployment is very easy and efficient.

MAPI Request comes to HLB , HLB has CAS servers published within , Administrator easily can stop MAPI request going specific CAS server etc. These deployments are also far more stable and easy to configure IMO. I think we will see more official statement soon and expecting to see ending support recommendations to HLB with CAS in the near future.

Oz Casey, Dedeal ( MVP north America)
MCSE 2003, M+, S+, MCDST
Security+, Project +, Server + (Blog) (Blog)


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