ServerIron ADX Global Server Load Balancing Guide 65
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Site persistence in GSLB using stickiness 1
•Client IP address/prefix
•Domain name the client requested
•Selected IP address for the request
This information is saved in a session table when the Sticky GSLB feature is enabled, and the GSLB
controller creates a sticky session for each client within the session table. Each session has a
special user type and source port or destination port number to distinguish from other sessions.
When a new request enters the system, the GSLB controller searches for the client IP and domain
name pair. If a match is found, the previously selected IP address will be returned.
To ensure the selected IP is still valid for the request, the GSLB controller checks for the following
conditions to be true before it returns the reply:
•Selected IP still belongs to the requested domain
•Selected IP is still active
Sticky GSLB is implemented as a GSLB policy, and it can be applied globally or on per host basis.
Algorithm
The following flow diagram illustrates how the Sticky GSLB algorithm works.
FIGURE 4 Flow diagram