This is a good read on how to configure Cookie Persistence on F5 LTM: Cookie Persistence – F5
Cookie Insert:
When you create a normal cookie persistence profile using GUI:
lbal4(Active)(tmos.ltm)# list persistence cookie PROF-COOKIE-INSERT
ltm persistence cookie PROF-COOKIE-INSERT {
defaults-from cookie
}
When you update the existing session cookie via GUI:
ltm persistence cookie PROF-COOKIE-INSERT {
cookie-name BIGIP-F5
defaults-from cookie
expiration 10:0
method insert
timeout 180
}
In the above example, expiration timer is set to 10 minutes. The expiration timer will refresh as long as new requests are sent to the F5 within the 10 minute interval.
The “timeout 180” is just an addition that is seen but doesn’t hold any meaning for cookie persistence (Insert, Passive & Rewrite) as outlined in this document: SOL13069
Expiration:
Specifies the cookie expiration date in the format d:h:m:s, h:m:s, m:s or seconds. Hours 0-23, minutes 0-59, seconds 0-59. The
time period must be less than 24856 days. You can use “session-cookie” (0 seconds) to indicate that the cookie expires when the
browser closes.