Forum Discussion
Pool member with sporadically listening service
- Jul 05, 2019
I recommend looking at how fast your monitor is configured to be (un)available. I recommend tcp_half_open (it's faster).
A very agressive monitor could be configured:
Interval: 1
Up interval: Disabled (it'll be online as soon as a succesful reply is received)
Time Until Up: 0
Time out: (however long you want the service to be available even when there's no successful response)
Manual resume: No
Additionally; you could add an alias service port. If the pool member is 10.10.10.10:4401 but the health monitor is to check 4402, you could specifiy 4402 in your monitor.
if an active pool member starts to listen on a port - how fast is F5 expected to connect to it
However fast your monitor interval + monitor up time + pool slow ramp combination is
Slow Ramp shouldn't prevent traffic as the intention described shouldn't generate too much of it... but you never know.
Possible troubleshooting:
Verify that you haven't configured a connection limit
There's a nice little tool called tcping (for windows). In cmd/powershell try running it before starting the service. Then you can see how quickly the vIP is online.
.\tcping.exe -t 10.10.10.10 4402
The mcpd process reports in your ltm log when it sees them member back online.
I recommend looking at how fast your monitor is configured to be (un)available. I recommend tcp_half_open (it's faster).
A very agressive monitor could be configured:
Interval: 1
Up interval: Disabled (it'll be online as soon as a succesful reply is received)
Time Until Up: 0
Time out: (however long you want the service to be available even when there's no successful response)
Manual resume: No
Additionally; you could add an alias service port. If the pool member is 10.10.10.10:4401 but the health monitor is to check 4402, you could specifiy 4402 in your monitor.
if an active pool member starts to listen on a port - how fast is F5 expected to connect to it
However fast your monitor interval + monitor up time + pool slow ramp combination is
Slow Ramp shouldn't prevent traffic as the intention described shouldn't generate too much of it... but you never know.
Possible troubleshooting:
Verify that you haven't configured a connection limit
There's a nice little tool called tcping (for windows). In cmd/powershell try running it before starting the service. Then you can see how quickly the vIP is online.
.\tcping.exe -t 10.10.10.10 4402
The mcpd process reports in your ltm log when it sees them member back online.
Hi Heino - thanks a lot for the quick reply. Your tips helped me figure out what was needed to get it working. First - after using tcping - I realized that the acmetool was only listening on localhost when started (my stupid oversight). But after fixing that I still needed to play with the monitoring interval and a delay I had added as an iRule to get it working.
It works now e.g. with a 2 second tcp monitor interval and a 3 second delay in the iRule. Longer tcp intervals and shorter delays make it fail sometimes.
I'll play around a bit more with the parameters and might give the alias service port a try (which might avoid the monitor interval dependency).
It looks a lot more promising now - thanks again!
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