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MB_F5_beginner_'s avatar
MB_F5_beginner_
Icon for Nimbostratus rankNimbostratus
Jan 04, 2017

UDP Health Monitor SEND/RECEIVE STRING SYNTAX

Hi Expert,   I am in the process of configuring a LB application for SNMP agent server pool for a network monitoring tool. I wanted create a custom UDP health monitor. I was reading the following:...
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Leonardo_Souza's avatar
Leonardo_Souza
Icon for Cirrocumulus rankCirrocumulus
Jan 04, 2017

Interestingly, both UDP and TCP monitors have send and receive string. However, I never saw these monitors implemented with send and receive string.

 

I guess this would be useful if you know the application, so what text to send and what it would reply. Same idea as with HTTP/HTTPS monitor.

 

The idea for the second monitor (ICMP) is simple. If the host is there, and the port is down, it will reply and F5 will mark it down. If not there, it will not respond, and continue up. This is why you need ICMP to make sure the server is marked down when is not alive.

 

If you use a send and receive string, if the string is not receive, it is marked down after the timeout. In this case, you don't need the ICMP to cover the situation when the server is down.