HP Traffic Director sa7220 - Manual (Page 28)

C H A P T E R 2 HP Traffic Director Server Appliances User Guide
16
Sticky Persistence
For source-ip based sticky, the relationship between the client IP
address and the fulfillment server remains in effect for the entire time
the SA8220 is online or until the sticky timeout value expires. In the
event of failover, the sticky relationship is lost. Cookie sticky remains
in effect while the browser is running or until the sticky timeout value
expires. Since the browser maintains the cookie, cookie sticky is
maintained in the event of failover. The system clocks on both
SA8220s must be synchronized for failover handling to work. You do
this by enabling NTP (Network Time Protocol) using the Boot
Monitor. The administrator can control the length of time a server is
forced to handle serial requests from a single client using the sticky
timeout value.
NOTE: SA7200 sticky
support allows for source
IP ONLY. All cookie
sticky RICH services will
be stuck to the same
server for the duration of
the sticky timeout value. Sticky-timeout
The current software version for the SA8220 treats the timeout
differently for cookie versus source-ip sticky. With source-ip sticky,
the timeout is reset with every connection from the client (so that the
timeout is effectively an "idle time"). With cookie sticky, the timeout
starts with the first connection from the client to the server, and never
gets reset. When the cookie expires, even if actively being used, the
next connection will be load balanced to a new server.
We recommend that you set the cookie sticky timeout value to at least
1.5 times the maximum amount of time a user will expect to be stuck
to a server. If you are uncertain of the exact setting, we recommend
using 43200 seconds (12 hours).
Server-timeout (SA8200/SA8220 only)
A server timeout, which causes a change in servers, can appear as a
cookie sticky state change. The recommended value for server
timeout is at least 1.5 times the maximum server response time.
We recommend that you set the value to 120 seconds.