Request Demo
  • On this page
Switch Monitoring with Nagios
  • Updated 3 days ago

What is Switch Monitoring?

Switch monitoring is the practice of polling network switches on a schedule to track port status, interface throughput, errors, and device health, so a failing uplink or a saturated port surfaces as an alert instead of a help desk ticket. Switches sit between every device and every service on your network, which means a single failing port takes down far more than one machine. Nagios XI monitors them agentlessly over SNMP, with thresholds you define.

Why Switch Monitoring Matters

Switch problems are rarely announced. A port negotiates down to a slower speed and nobody notices until an application feels sluggish. An interface starts accumulating errors and discards weeks before it fails outright. An uplink saturates during a backup window and everything behind it slows to a crawl. None of these show up on a dashboard that only tracks whether the switch responds to ping. Watching per-interface state and throughput is what turns those into alerts you can act on ahead of an outage.

What the Network Switch and Router Wizard checks

The Network Switch and Router Wizard (Configure > Configuration Wizards) discovers a device’s interfaces over SNMP and sets up monitoring in a few steps:

  • Port and interface status. The check_snmp_interface_status plugin tracks whether each monitored interface is up or down, so a dropped link is a Critical alert rather than a mystery.
  • Interface throughput. The check_throughput plugin measures traffic in and out per interface, with Warning and Critical thresholds you set, so a saturated uplink pages someone before users feel it.
  • Device health. Poll CPU, memory, and other vendor-exposed OIDs over SNMP to confirm the switch itself is operating within normal capacity.
  • SNMP traps. Receive and act on traps the device sends on its own, for events that are announced rather than polled.

Cisco Meraki switches have their own dedicated Meraki Switch Wizard, and the SNMP Walk Wizard covers devices that expose metrics you want to monitor but that no wizard handles directly.

What Lives In Other Nagios Solutions

Switch monitoring in Nagios XI answers “is this interface up, and how much traffic is moving through it.”

Two related capabilities are genuinely useful alongside it, but they’re separate solutions with separate licenses:

  • Flow analysis. If you need to know what that traffic is, which conversations, which talkers, which applications are consuming the bandwidth, that’s Nagios Network Analyzer, which handles NetFlow, sFlow, J-Flow, and IPFIX. XI tells you an interface is at 94 percent. Network Analyzer tells you why.
  • Syslog collection and analysis. Centralizing switch syslog output for search and alerting is Nagios Log Server, not a feature of the switch wizards in XI.

Nagios XI monitors device and interface state; it doesn’t inspect traffic for threats. That capability, Suricata-based IDS/IPS alongside packet capture and Nmap scanning, is part of Network Analyzer.

How To Implement It

  1. Scope the devices. Identify which switches matter and, on each, which interfaces are actually worth alerting on. Monitoring every port on every switch generates noise that teaches people to ignore alerts. Uplinks, trunks, and ports serving critical Hosts are the place to start.
  2. Enable SNMP on the devices. Use SNMPv3 with authPriv where supported, and make sure the Nagios server can reach the device on 161/udp for polling and receive traps on 162/udp.
  3. Run the wizard. The Network Switch and Router Wizard discovers interfaces and lets you select which to monitor and at what thresholds.
  4. Set thresholds that reflect your network. Throughput Warning and Critical levels should be based on the actual capacity of each link, not a single global default.
  5. Use the history. Capacity Planning and Availability reports in Nagios XI turn months of interface data into evidence for when a link genuinely needs upgrading.
View Transcript

0:00 hey everyone this is Hueche from nagios
0:03 and today I’ll be showing you how to
0:04 monitor a switch so you can be quickly
0:06 alerted when a switch is down
0:10 [Music]
0:13 a switch is a critical component of any
0:15 network it’s responsible for routing
0:17 traffic between devices if a switch
0:19 fails it can cause an outage impacting
0:21 your network with nagios XI you’ll be
0:24 able to monitor your switch for a
0:26 variety of metrics such as Port status
0:28 bandwidth utilization and Errors By
0:31 monitoring these metrics you can detect
0:33 problems with your switch before they
0:35 impact your network
0:36 and high heels XI can also send you
0:38 alerts when it detects those problems
0:40 this allows you to act quickly to
0:42 resolve them before they cause an issue
0:45 now before you get started with
0:46 monitoring your switch make sure your
0:48 switch supports SNMP SNMP is enabled and
0:52 that you know the SNMP Community string
0:55 with all that said let’s check out how
0:57 easy it is to monitor a switch first go
1:01 to the configure Tab and click on
1:02 configuration Wizards
1:04 on the top icon tray we will select the
1:07 network icon
1:08 from there we will find a switch
1:10 configuration wizard labeled network
1:12 switch slash router and in just a few
1:15 steps we will have this configured and
1:17 ready to monitor
1:19 and the first step at a wizard you can
1:21 choose which switch to monitor how you
1:23 want it to communicate with the XI via
1:25 SNMP how you want to see the ports they
1:28 are discovered and the thresholds for
1:30 the metrics the wizard will set up
1:33 so first we’ll enter the IP address of
1:36 the switch
1:37 you can also change the port number if
1:39 needed
1:41 then we’ll enter the SNMP Community
1:43 string
1:46 and the monitoring options you can
1:48 choose how you want the ports to be
1:49 displayed the default is by number but
1:52 you can have them displayed by Port name
1:54 description or by an alias
1:58 we are going to skip the bulk
2:00 configuration at this time since we are
2:02 configuring only one switch but if you
2:04 would like to configure multiple
2:05 switches here’s where you would paste in
2:08 a list of IP addresses which would save
2:10 a lot of time
2:12 moving to the bottom we see default
2:14 values for input rate and output rate
2:16 which are our warning and critical
2:18 thresholds for alerting you will
2:20 probably want to change the default
2:21 input output values of the 50 to
2:24 something higher unless you want to get
2:26 a warning anytime the switch traffic
2:27 hits 50.
2:30 below you will also see default Port
2:33 speed if you are monitoring a gigabit
2:35 switch you are going to want changes to
2:37 1000
2:39 hit next at the bottom to move to the
2:41 next page
2:43 under switch details you can give the
2:46 device a name or keep the default of the
2:49 IP address
2:50 for example we are going to call this
2:52 Cisco switch
2:55 we will leave the bandwidth and Port
2:57 status values alone at this time
3:01 scroll down to the bottom and hit next
3:02 to move to the final page
3:07 here we can set the interval that the
3:10 switch is checked the default is 5
3:12 minutes we will leave it at that
3:14 next we have the settings for when a
3:16 problem is detected
3:19 once the problem is detected nagios XI
3:21 will recheck the device every minute or
3:24 whatever the time period you choose up
3:26 to five times before it sends you a
3:27 notification
3:29 now we will click finish
3:31 from here you can click the status
3:33 details link under the other options
3:36 this will bring you to the whole status
3:38 page where you can view that the switch
3:40 is up and being monitored by nagios XI
3:44 thanks for watching I hope you found
3:46 this video helpful and if you have any
3:48 questions visit us at support.nog
3:50 hills.com be sure to subscribe and stay
3:53 tuned for more videos coming soon
3:55 [Music]
4:09 [Applause]

Why Nagios XI for Switch Monitoring

Nagios XI monitors switches agentlessly over SNMP, so there’s nothing to install on the network gear itself, which is the only practical approach for hardware that can’t run an agent. Switch Hosts and Services sit in the same status views, notification chains, and escalation policies as your servers and applications, rather than in a separate network-only console.

Thresholds are yours to define, so you always know why an alert fired. And when a single monitoring server can no longer keep up with the check volume, the Network Switch and Router Wizard was built to distribute its checks through Nagios Mod-Gearman (NMG).

Ready to Monitor with Nagios XI?

Get comprehensive infrastructure monitoring with our enterprise solution.

Request Demo Learn More
  • On this page