HP Multi-Site Traffic Director sa9200 - Manual (Page 11)

Theory of
Operations
NOTE: HP Traffic
Director refers to either
an HP Traffic Director
Server Appliance, Model
SA7200 and SA7220; or
HP e-Commerce Director
Server Appliance, Models
SA8200 and SA8220. Typical load balancers work by balancing traffic over a Local Area
Network (LAN) to a Web farm. The HP Multi-Site Traffic Director
Server Appliance SA9200 extends this balancing to multiple sites
over a Wide Area Network (WAN). By balancing referrals to each
site, the SA9200 enables enterprises and Web hosting services to
integrate geographically distributed content and services.
The advantages of such integration are many, including:
• There is increased fault tolerance and availability owing to
redundant sites. Multiple active sites permit uninterrupted service
in the event of a localized outage in the data network.
• Customer response times are improved by directing users to
uncongested sites or data centers.
• Easy scaling of server farms can be accomplished.
Multi-site load balancing works best in concert with HP Traffic
Directors. The SA9200 also supports multi-site load balancing with
sites that do not have HP Traffic Directors. In this case, the sites are
balanced on the basis of availability, and not based on proprietary
metric information.