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Building NLB Exchange 2010 RTM CAS / HT Servers (Hyper-V) – Part 1

UPDATE: 07/12/2011

Since this has been a topic of debate, I’ve added an additional network diagram (not one generated in my lab) so that it may become a little clearer as to how NLB works. The understanding for this network configuration comes directly from Michael Platts’ blog post: Balancing Act: Dual-NIC Configuration with Windows Server 2008 NLB Clusters. 

I know I’ve been pretty offline regarding this blog but I fully intend to jump start it soon.

This post was created using Joe Hoegler’s post as a guide. All Exchange 2010 client access to mailboxes and other resources go through the CAS server. Clients no longer connect to the Exchange server directly for anything. With this said, it makes sense to build CAS servers in an HA configuration. This article was created to detail the steps required to create a load balanced CAS / HT server using Windows Network Load Balancing.

Before deploying the NLB configuration, the following should be carefully considered:

“You achieve load balancing for Hub Transport servers when you install more than one Hub Transport server in the same Active Directory site. By default, connections to Hub Transport servers are automatically load balanced if more than one Hub Transport server is deployed in an Active Directory site. If one Hub Transport server is unavailable, the operational Hub Transport servers continue to accept connections. If all Hub Transport servers in an Active Directory site are unavailable, messages are queued until a Hub Transport server becomes available or the messages expire.

Load balancing of outbound connections to remote domains is achieved by specifying more than one Hub Transport server in the same Active Directory site as a source server for the corresponding Send connector. Load balancing doesn’t occur when the source servers for a Send connector are located in different Active Directory sites.

Note:
If the Hub Transport server is installed on the same hardware as the Mailbox server role, load balancing may not occur. When the Hub Transport server role is on the same hardware as the Mailbox server role, the local server is preferred for all messages that are sent by users who have mailboxes on that server. Therefore, in this scenario, true load balancing does not occur.” Taken from: http://technet.microsoft.com/en-us/library/bb125239.aspx

Requirements

Two or more servers running Windows 2008 R2 (earlier version do have NLB built in but for this blog entry, I will be using Windows 2008 R2). Ideally each server will be configured with two NICs. One for client access and one for the cluster heartbeat. NLB requires all IPs to be on the same network.

Notes on Hyper-V

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March 19, 2010 Posted by ivorb | Exchange 2010 RTM, NLB | NLB Windows 2008 R2 | 10 Comments