Configuring the WSM using Device Manager

Effects of using source IP address for session persistence

Until recently, the only way to achieve TCP/IP session persistence was to use the source IP address as the key identifier. Two concerns with basing session persistence on a packet's IP source address are:

• Many clients sharing the same source IP address (proxied clients)

Proxied clients appear to the WSM as a single source IP address and do not take advantage of SLB on the WSM. When many individual clients behind a firewall use the same proxied source IP address, requests are directed to the same server, without the benefit of load balancing the traffic across multiple servers. Persistence is supported without the capability of effectively distributing traffic load. Also, persistence is broken if you have multiple proxy servers behind the WSM performing SLB. The WSM changes the client's address to different proxy addresses as attempts are made to load balance client requests.

• Single client sharing a pool of source IP addresses

When individual clients share a pool of source IP addresses, persistence for any given request cannot be assured. Although each source IP address is directed to a specific server, the source IP address itself is randomly selected, thereby making it impossible to predict which server will receive the request. SLB is supported, but without persistence for any given client.

See also:

• About session persistence
• Using cookies for session persistence
• Using SSL session ID for session persistence
• Server load balancing basics
• Virtual server load balancing
• About cookie-based persistence
• Configuring cookie-based session persistence
• Examples of cookie values
• SSL session ID-based persistence
• Configuring SSL session ID-based persistence