F5 BIG-IP appliances sit in front of critical applications, so monitoring them well means watching more than just whether the box itself is up — the traffic it's distributing matters just as much.
What to monitor on an F5
- Device health — CPU, memory, and overall system status of the BIG-IP appliance itself, the same baseline as any other network device
- Virtual server status — whether each virtual server (the address clients actually connect to) is up, down, or in a degraded state
- Pool member health — the individual backend nodes behind a virtual server; a pool with members silently marked down is one of the most common causes of a "the app is slow" complaint that isn't visible from the application side alone
- Throughput — connections and bandwidth through the device, useful for capacity planning
Why this matters more than it looks
An F5 in a degraded state (say, half its pool members failing health checks) can keep serving traffic while performance quietly degrades, since the remaining healthy members simply absorb more load. Watching pool member status directly, rather than just the application's own uptime, is what catches this before end users notice.
Setup
F5 devices are monitored over SNMP using F5's own MIBs for virtual server and pool status, alongside the standard interface and system checks covered in Monitoring Network Devices. As with any SNMP-based device, confirm the community string or SNMPv3 credentials and any SNMP access restrictions on the device before adding it, and add it as its own host so its dashboards and alerts stay scoped to the load balancer rather than mixed in with the servers behind it.