Overview

SiteRM Frontend has built-in SNMP monitoring that collects topology information, interface stats, and MAC tables from your network switches. This is configured via the snmp_params section of your ansible-conf.yaml file (see Enable Switch Control).

A Custom SNMP Exporter is an additional optional component — the Prometheus SNMP Exporter — that exposes per-interface counters, optics, CPU/memory, and other OID-based metrics from your network devices in Prometheus format. These metrics can then be visualized in Grafana dashboards alongside other site monitoring data.

When do you need a Custom SNMP Exporter?

  • You want per-interface byte/packet counters from switches in Prometheus/Grafana
  • You want optical signal metrics (DWDM, SFP/QSFP power levels)
  • You want CPU and memory utilization from switches in Prometheus format
  • Your site monitoring infrastructure already uses Prometheus

Architecture

Network Switches (SNMPv1/v2c/v3)
         │
         │ SNMP queries (UDP 161)
         ▼
Prometheus SNMP Exporter  ← scrape config
  (HTTP :9116)
         │
         │ /metrics
         ▼
   Prometheus Server
         │
         ▼
     Grafana

This complements (not replaces) the built-in SiteRM SNMP monitoring. SiteRM uses SNMP for topology discovery; the exporter provides time-series metrics for dashboards and alerting.

Prerequisites

  • A Linux host with network access to all managed switches on UDP port 161
  • Docker or a native Go environment (for running the exporter)
  • SNMP credentials for your switches (community string for v1/v2c, or user credentials for v3)
  • A Prometheus server to scrape the exporter

Step 1 — Install the Prometheus SNMP Exporter

Option A — Docker (Recommended)

docker run -d \
  --name snmp-exporter \
  --restart always \
  -p 9116:9116 \
  -v /etc/snmp_exporter:/etc/snmp_exporter:ro \
  prom/snmp-exporter:latest

Option B — Native Binary

Download the latest release from https://github.com/prometheus/snmp_exporter/releases:

wget https://github.com/prometheus/snmp_exporter/releases/download/v0.26.0/snmp_exporter-0.26.0.linux-amd64.tar.gz
tar xzf snmp_exporter-0.26.0.linux-amd64.tar.gz
cp snmp_exporter-0.26.0.linux-amd64/snmp_exporter /usr/local/bin/

# Create systemd unit
cat > /etc/systemd/system/snmp-exporter.service <<'EOF'
[Unit]
Description=Prometheus SNMP Exporter
After=network.target

[Service]
User=snmp-exporter
ExecStart=/usr/local/bin/snmp_exporter --config.file=/etc/snmp_exporter/snmp.yml
Restart=always

[Install]
WantedBy=multi-user.target
EOF

systemctl enable --now snmp-exporter

Step 2 — Configure SNMP Module

The SNMP Exporter uses a snmp.yml configuration file that defines which OIDs to collect. You can generate it with the snmp_exporter generator or use the pre-built modules provided in the container.

Create /etc/snmp_exporter/snmp.yml with modules for your switch vendor. Below are examples for the most common vendors:

SNMPv2c Configuration (Dell OS9/OS10, Arista EOS, Cisco NX-OS)

# /etc/snmp_exporter/snmp.yml
modules:
  if_mib:                           # Module name (referenced in Prometheus scrape config)
    walk:
      - 1.3.6.1.2.1.2.2            # ifTable
      - 1.3.6.1.2.1.31.1.1         # ifXTable (64-bit counters)
      - 1.3.6.1.2.1.1              # sysDescr, sysName, etc.
    auth:
      community: public             # Replace with your SNMP community string
    version: 2
    timeout: 10s
    retries: 3

SNMPv3 Configuration (Juniper Junos)

modules:
  junos_if:
    walk:
      - 1.3.6.1.2.1.2.2            # ifTable
      - 1.3.6.1.2.1.31.1.1         # ifXTable
      - 1.3.6.1.4.1.2636.3.1       # Juniper enterprise MIB
    auth:
      security_level: authPriv
      username: snmpv3user           # Replace with your SNMPv3 username
      password: authpassword         # Replace with auth password
      auth_protocol: SHA             # SHA or MD5
      priv_protocol: AES             # AES or DES
      priv_password: privpassword    # Replace with privacy password
    version: 3
    timeout: 15s
    retries: 3

Supported auth_protocol values: SHA, MD5 Supported priv_protocol values: AES, DES

Step 3 — Configure Prometheus Scrape

In your Prometheus configuration (prometheus.yml), add a scrape job for each switch:

scrape_configs:
  - job_name: 'snmp_switches'
    static_configs:
      - targets:
          - 192.168.1.10    # Dell switch 1
          - 192.168.1.11    # Dell switch 2
          - 192.168.1.20    # Arista switch
    metrics_path: /snmp
    params:
      module: [if_mib]      # Must match the module name in snmp.yml
    relabel_configs:
      - source_labels: [__address__]
        target_label: __param_target
      - source_labels: [__param_target]
        target_label: instance
      - target_label: __address__
        replacement: snmp-exporter-host:9116   # IP/hostname of the SNMP exporter

  - job_name: 'snmp_juniper'
    static_configs:
      - targets:
          - 192.168.1.30    # Juniper switch
    metrics_path: /snmp
    params:
      module: [junos_if]
    relabel_configs:
      - source_labels: [__address__]
        target_label: __param_target
      - source_labels: [__param_target]
        target_label: instance
      - target_label: __address__
        replacement: snmp-exporter-host:9116

Step 4 — Verify the Exporter

Test manually that the exporter can reach your switches:

# Query the exporter for a specific switch
curl "http://localhost:9116/snmp?target=192.168.1.10&module=if_mib"

# You should see Prometheus-format metrics like:
# ifInOctets{ifAlias="uplink",ifDescr="GigabitEthernet1/0/1",...} 1234567890
# ifOutOctets{...} 9876543210

Check that the exporter is running:

curl http://localhost:9116/metrics

SNMP Configuration Reference

The SNMP exporter parameters map directly to the easysnmp session parameters used internally by SiteRM. The table below maps between the two:

SNMP Version SiteRM ansible-conf.yaml (session_vars) SNMP Exporter snmp.yml (auth)
v1 version: 1, community: public version: 1, community: public
v2c version: 2, community: public version: 2, community: public
v3 version: 3, security_level: authNoPriv version: 3, security_level: authNoPriv
v3 version: 3, security_level: authPriv version: 3, security_level: authPriv

For a full list of SNMPv3 session parameters supported by SiteRM’s built-in SNMP client, see easysnmp session documentation.

Useful OID References by Vendor

Vendor Key MIBs OID Prefix
All (IF-MIB) ifTable, ifXTable (interface counters) 1.3.6.1.2.1.2.2, 1.3.6.1.2.1.31
Dell OS9/OS10 Dell EMC OS MIBs 1.3.6.1.4.1.674
Arista EOS Arista enterprise MIBs 1.3.6.1.4.1.30065
Juniper Junos Junos enterprise MIBs 1.3.6.1.4.1.2636
Cisco NX-OS Cisco enterprise MIBs 1.3.6.1.4.1.9
Azure SONiC Standard IF-MIB + enterprise 1.3.6.1.2.1.2.2

Troubleshooting

Symptom Likely Cause Resolution
Error scraping target in Prometheus SNMP community wrong or UDP 161 blocked Verify community string; check firewall rules
Exporter returns empty metrics No matching OIDs walked Use a more general module or add the correct OID walk entries
SNMPv3 authentication errors Wrong auth/priv protocol or password Double-check auth_protocol, priv_protocol, and passwords
Timeout errors Switch unreachable or overloaded Increase timeout in snmp.yml; verify network path
Missing interface labels ifAlias not configured on switch Configure interface descriptions on the switch

Additional Resources