Debugging Health Monitor - Node being randomly marked down and then up.

How is the health monitor configured?


Hi Thanks for responding to me. I have inserted two images showing the configuration of the monitor and its usage.

Thanks for your help. The access logs file don't show any problems with the monitored web-asset, there is always 200 OK response.

Hi Kevin,

Your views on the config (screenshots) which I sent through would be very much appreciated.

James

Hi,

Please can anyone help me with this issue. Screenshot showing monitor config in the message trail.

thanks

So is this unencrypted traffic on the server side of the BIG-IP? If it is, your best first step is to do a wire capture to look at the request and response traffic:

tcpdump -lnni [server side vlan name] -Xs0 port [web server port] and host [web server IP]

Without any application traffic going to the VIP, you should see the monitor traffic coming from the BIG-IP self-IP. You're then looking for what the request looks like and what the response looks like. You also stated that you always receive a 200 response. How are you testing when you see this response?

Thanks Kevin,

I am tailing the access log files for the server, I could see request from the monitor returning a 200 response. But every so often, there was a http 0 status.

I also noted that the monitor requests are using HTTP/0.9. I will update it to HTTP/1.1 after seeing the document below.

https://support.f5.com/kb/en-us/solutions/public/3000/200/sol3224.htmlhttp : suggests that When an HTTP 0.9 request is sent to an HTTP 1.1 server, the server may not respond as expected.

Hopefully that will help.