Ever have an issue with the interface active monitor being added back to devices after being removed? This is in fact, working as intended for WhatsUp Gold. Let me explain why! During the discovery process WhatsUp Gold uses device roles in order to determine which monitors should be applied to certain device types. The interface active monitor is within the device role for switches, routers, and firewalls. This means during the discovery it is going to add the interface active monitor to the device, which means it will actually have an active monitor for every interface on the device. Any port that has a connection during the discovery with have it’s interface active monitor ‘Enabled’, whereas any port that has nothing connected during the discovery will still get an active monitor but it is left ‘Disabled’.
So, let’s say I don’t care about interface X and certainly don’t want to be alerted by it. Well, let me just remove the monitor from the device. WRONG! We should ‘DISABLE’ the monitor instead. By removing the monitor, during your next discovery WhatsUp Gold’s discovery will say “hey there is a switch here…let me add the interface active monitor!” and will add the monitor back. However if the monitor was DISABLED as opposed to being REMOVED then WhatsUp Gold will not RE-ENABLE the monitor. Makes sense right? There is also another large reason to not remove interface active monitors and that is because the link lines displayed in Layer-2 maps within WhatsUp Gold depend on those monitors. If you remove the monitor, you’ve also removed it from all of your map views containing. Whereas if it were disabled, the link line would still show on the map.