SNMP: setup, interfaces, OIDs, and alerts

Before enabling SNMP

Enable SNMP on the device, restrict it to the Edge Agent or monitoring bridge, and verify firewall and routing. v1/v2c use a community; v3 uses the authentication and privacy settings supported by the device. Prefer v3 and never expose UDP 161 broadly to the Internet.

ISP Dude device setup

Enable SNMP, choose the actual version, and enter credentials. With Edge Agent, credentials are delivered only to the authenticated tenant Agent. Save the correct host and Environment first. A timeout may be caused by ACL, community, version, routing, or power state and does not identify the cause by itself.

Retrieve and select interfaces

Retrieve Interfaces returns each interface index and name without automatically selecting new ports. Choose only operationally meaningful interfaces, up to 20 per device. Previously saved interfaces remain selected when discovery is refreshed.

Saving creates the required state, negotiated-speed, and counter OIDs separately from operator-defined custom OIDs. If firmware, modules, or interface layout change, retrieve the list again and verify the ifIndex values before trusting previous associations.

Traffic and value formatting

The first successful counter sample establishes a baseline. Later samples are converted into rates and formatted from bits per second through Kbps, Mbps, or Gbps. A single reading cannot provide a traffic rate because no elapsed interval exists yet.

SNMPv2c and v3 prefer 64-bit high-capacity counters; SNMPv1 must account for 32-bit rollover on busy interfaces. Compatible radio interfaces may also expose signal, noise, SNR, and CCQ. Treat missing radio values as unsupported or unavailable until the device and OIDs have been checked.

Interface alerts

Link-state change, negotiation degradation, and abnormal saturation are available. Set saturation percentage and minimum duration from observed normal traffic. Alerts respect the device notification switch and produce open and recovery events.

Discovery and custom OIDs

Smart analysis tests a targeted catalog for systems, servers, radios, UPS devices, and standard capabilities. Select or clear supported OIDs directly, then use the normal device save action. Selected supported OIDs remain available in the device detail popup; the Show on node option, off by default, also adds the result directly to the device on the Network Map. Reopening the device shows the configuration actually stored. Custom OIDs require a numeric path, clear description, and a successful Test OID request. Interface-generated checks remain under Automatically managed OIDs.

On MikroTik, interface and radio OIDs depend on the RouterOS ifIndex of each device, so fixed indexes must not be reused across routers. Radius diagnostics automatically display only reliable scalar values and convert sysUpTime from TimeTicks; speed and counters require interface discovery first.

SNMP in ISP Radius 2.0

Radius 2.0 selects one general SNMP method—Edge Agent or a configured classic MikroTik bridge—for manual and automatic polling. It does not choose a separate Agent per account and does not silently fall back when the selected Agent is unavailable.

Checklist

• Restrict SNMP sources
• Prefer v3 where supported
• Verify version and credentials
• Select useful interfaces only
• Refresh ifIndex after device changes
• Wait for two samples before evaluating speed
• Tune threshold and duration
• Test custom OIDs
• Diagnose timeouts rather than guessing