I was discussing some F5 LTM Healthcheck Monitor capabilities with a colleague of mine at work the other day, when he brought up a great question.
What does an F5 LTM use for a source IP address when connecting to pool members for the healthcheck monitor service? Especially on a Multi-Network setup.
To answer this question we have to consider the typical LTM cluster set up . Usually set up in pairs of two(2), one acting as an Active unit and the other as Standby unit. Each unit has it’s own Self IP for each “network leg” it is attached to. The Active and Standby unit also share a “Floating IP address”, which is used for the backend traffic to pool members. But back to the question, let’s use the following example: