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Lightspeed_VT_5's avatar
Lightspeed_VT_5
Icon for Nimbostratus rankNimbostratus
May 22, 2008

Monitor flapping

While reviewing today's "ltm" logfile on our LTM 1500, I see random monitor flapping for reasons I can't determine. When the flaps happen, all application users lose their session.     I'm...
management
monitoring
Deb_Allen_18's avatar
Deb_Allen_18
Historic F5 Account
Jul 28, 2008
The HTTP monitor is the best choice for webserver monitoring.

You should add a Receive string, but I don't think that's the issue here: Not specifying a receive string simply means you would get false positives (UP when it isn't really), rather than false negatives, since ANY response will mark the pool member UP.

Have you lowered the interval / timeout values from the default? If so, I'd look for slow responses.

You might also try using a more specific request string that includes the HTTP version, host header, & connection: close options, as in AskF5 Solution 3224: Click here 

GET /myfile.cfm HTTP/1.1\nHost: \nConnection: Close\n

hth

/deb