CSS keepalive vs F5 monitor

Hi,

 

I am struggling to figure out closest match for Cisco CSS keepalive (=F5 monitor) settings. Based on CSS commandline manual (v 8.20) keepalive parameters are as following:

 

frequency - To specify the frequency to send keepalive messages to the IP address, def 5s - should equal Up Interval. That's because of following description:

 

retryperiod - When a service has failed to respond to a given keepalive message (the service has transitioned to the dying state), the retry period specifies how frequently the CSS tests the service to see if it is functional, def 5s

 

Assuming that frequency is changed to 10s and retryperiod left at def it's necessary to use both Interval (=retryperiod) and Up Interval (=frequency)

 

This is simple, but in frequency description there is note:

 

The timeout for a keepalive is related to the configured keepalive frequency. In WebNS 5.1 and earlier versions, the timeout is equivalent to the keepalive frequency. In version 5.2, the timeout is one second less than the keepalive frequency. There seems to be no separate setting for timeout (and Cisco timeout is not equal to F5 timeout).

 

Seems that in never version if there is frequency set to 10s, timeout is 9s.

 

There are is as well parameter maxfailure (def 3) that has not direct counterpart on F5 (this is calculated based on Interval/Up Interval and Timeout)

 

My wild guess for Cisco setting: frequency - 10s maxfailure - 3 (def value) retryperiod - 5s (def value) timeout (fixed) - 9s (frequency-1)

 

in F5 will be: Interval - 5s Up Interval - 9s Timeout - 28s

 

I expect that it should work like that:

 

• When service is up check will be performed every 9s - so a bit more frequent than on Cisco - but can't figure out how to keep 10s and fulfill other requirements
• After 3 failed checks (27s) service will be marked down
• Then service will be checked every 5s until it's up - after first reply to check. I wonder what is timeout here - 5s? What if there is first check issued, 5s passes, then service responds to this check after 8s?
• When service is back up it will be checked every 9s again.

Piotr