OCS 2007 R2 requires Hardware Load Balancers for different scenarios:
- Enterprise pools with more than one Front End server.
- Edge server arrays.
- Director arrays.
- Multiple CWA servers for redundancy.
Microsoft has tested and approved a few different vendor products to meet the HLB requirements for OCS 2007 R2.
The list includes:
You can get more information about the approved HLBs at this link: http://technet.microsoft.com/en-us/office/ocs/cc843611.aspx
The above HLBs are not the only ones that are supported by Microsoft, though. If an HLB meets the requirements here, then they are also fully supported: http://technet.microsoft.com/en-us/library/dd572362(office.13).aspx