I have an issue which I wonder if a VLAN group, which I don't yet understand fully from the available documentation, would help.
There is a BIG-IP active/standby pair monitored via SNMP. The SNMP client connects to a floating address (not a virtual server) in the internal VLAN of the F5 device, querying its SNMP server. It does so so that it would always get the state of the active device.
From time to time, the connection from the SNMP client to the F5 active device will timeout, causing the SNMP query to fail and generate a false alarm through an alert to application service owners.
A packet capture on the F5 shows that when the issue occurs, the BIG-IP uses "127.0.0.1" as the source address in its response packet, making the SNMP response invalid. Also, the same capture file shows that there are occasions when the SNMP query comes from the external SNMP client address directly destined for "127.0.0.1".
The SNMP client machine resides in a VLAN that is also present on the F5 pair, which has a floating IP address as well as a local IP address on each of the F5 devices in that VLAN.
Any help is appreciated.