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8 Best Tools for Monitoring WAN Circuits (Review)

Monitoring WAN circuits is an important task of any network administrators. WAN circuits typically have a much lower available bandwidth than local area networks and as such, they can easily become congested, possibly rendering them unusable. For that reason, administrators must use the proper tools to keep an eye on them. Adequate WAN monitoring will also allow administrators and their managers to observe the evolution of WAN circuits utilization as well as its distribution in time.

Many tools are available to measure the actual usage of WAN circuits. We’ve gathered this list of some of the best of them and we’re about to give you a brief review of the best tools.

Before we begin, we’ll briefly sidetrack to explore what WAN monitoring is and how it’s done. It’s actually not much different from monitoring local area networks and, thanks to the Simple Network Management Protocol, or SNMP, there is a standard, almost universal way of doing it. We’ll also discuss the SNMP protocol not with the goal of making you an expert but enough so that you’ll be in a better position to fully appreciate the rest of this article. Next, we’ll describe the benefits of using WAN monitoring tools. And finally, we’ll review eight of the best WAN monitoring tools we could find.

Monitoring WAN Circuits – What It Is And How It’s Done

There are several ways than WAN circuits can be monitored but before we dig into that, let’s see what we mean when we’re talking about WAN monitoring. The idea of monitoring WANs—at least in the context of this article—has to do with measuring the utilization of the available bandwidth. While other systems and tools will let you analyze traffic patterns as well as have a detailed overview of a WAN circuit’s utilization, this is not what this article is about.

So, what exactly is bandwidth monitoring? If you think of a WAN circuit as a highway, the bandwidth utilization would be the number of cars that pass on the highway by unit of time. It is the exact same things for WAN circuits and bandwidth utilization refers to the number of bits that are transmitted or received on the circuit every second.

And if you’re wondering how we can manage to monitor bandwidth utilization, the answer is simple, we count bits. Really! Well, we don’t actually count them, the networking equipment—typically the WAN router—does. Then the monitoring tool reads the devices counters, does some math, and displays the results. What makes it possible is something called the Simple Network Management Protocol, or SNMP.

SNMP 101

Although the “S” in SNMP stands for simple, SNMP is actually quite complex. But just as you don’t have to be an auto engineer to drive a car, you don’t have to know all about SNMP to use it. However, it’s good to have at least an idea of how it works.

SNMP is basically a communication protocol that defines how an SNMP management system car read and write operational parameters in remote devices. The parameters are referred to as OIDs, an acronym for Object IDentifiers. In the context of monitoring bandwidth consumption, two OIDs are of particular interest, the bytes out and the bytes in counters. These are the counter the networking equipment uses to count traffic.

Before we go any further, let’s talk about the security, or lack thereof, in SNMP. The protocol dates back from when IT security was not an issue. As such, it only has minimal security. An SNMP manager connecting to an SNMP-enabled device will transmit a community string with its request. If the string matches that configured in the equipment, the request will be carried out. Devices typically have two community strings, one for read-only OIDs and one for modifiable ones.

Let’s see how a monitoring system uses SNMP to monitor WAN bandwidth. The system will periodically read the bytes in and out counters of the networking device’s WAN-facing interface at know intervals of typically five minutes. It will then store the read values in some sort of database. The rest is pretty much just mathematics. The monitoring system subtracts the previous counter value from the current one to get the number of bytes transmitted or received in five minutes. It can then multiply that number by eight to get the number of bits and divide it by 300–the number of second in five minutes–to get the number of bits per second. This information is usually plotted on a graph showing its evolution in time and stored in a database.

You should be aware that what you get out of this process is average utilization in bits per second over a five-minute time span. Imagine a 100 Mbps interface. In the five minutes between samples, the actual traffic level could have been at 100 Mbps for 150 seconds and at 0 for 150 seconds and it would display an average traffic of 50 Mbps although the interface was maxed out for half of the five minutes. This is a shortcoming of every SNMP monitoring system. It won’t give you instantaneous, live utilization figures.

The Benefits Of Using Wan Monitoring Tools

There are several reasons why network management software is useful. First and foremost, it will help you pinpoint areas of contention. In a WAN circuit becomes overutilized, its performance will degrade, something you want to avoid. By keeping an eye on WAN bandwidth utilization you have a chance to detect high utilization—and fix it—before it starts affecting users.

Capacity planning is another big advantage of WAN monitoring. WAN circuits are relatively expensive and often have a limited bandwidth that was deemed sufficient when they were installed. But just like disk storage, bandwidth needs keep increasing. By monitoring the evolution of WAN circuits bandwidth, you’ll be able to see which ones need to be upgraded and when.

WAN bandwidth monitoring can also come in handy when troubleshooting poor application performance. When a user complains that some remote application has slowed down, looking at the WAN utilization could give you a pretty good idea whether or not the problem is caused by WAN congestion. If you see low WAN utilization, you can likely concentrate your troubleshooting efforts elsewhere.

The Best Tools For Monitoring WAN Circuits

Let’s have a look at the best WAN monitoring tools available. Our list contains a combination of paid and free tools. All of our picks are excellent products and choosing one over the other will largely be a matter of personal preference. Most paid products offer a free trial, giving you a chance to see first-hand if they meet your needs.

1. SolarWinds Network Performance Monitor (FREE TRIAL)

SolarWinds rarely requires introduction amongst network administrators. If you don’t know it, the company is famous for its excellent network administration tools, including an excellent help desk management software or one of the best switch port monitoring software. SolarWinds is also famous for its free tools that address specific needs. They have, for instance, an excellent subnet calculator and a very good TFTP server.

SolarWinds NPM - Network Summary

SolarWinds’ flagship product is called Network Performance Monitor, or NPM. It is a full-featured network monitoring solution with great functionality. The SolarWinds NPM polls WAN routers using the SNMP protocol to reads their interface counters. It stores the results in an SQL database and uses the polled data to build graphs showing each WAN circuit’s usage.

The SolarWinds Network Performance Monitor boasts a user-friendly GUI and adding a device is as simple as specifying its IP address or hostname and SNMP community string. It then queries the device, lists all the SNMP parameters that are available, and allows you to pick those you want to monitor and display on your graphs. For WAN monitoring, you’ll be specifically interested in the WAN interface traffic counters but you could also include error counters as well as CPU and memory utilization counters.

Prices for the SolarWinds Network Performance Monitor start at just under $2 995 and vary according to the number of devices to monitor. A detailed quote can be obtained by contacting the SolarWinds sales team. And if you’d want to try the product before you buy, a free 30-day trial is available, as it is for most paid SolarWinds products.


The Paessler Router Traffic Grapher, which is usually just called PRTG, is another excellent monitoring system. It is an enterprise-grade product with claims to be the fastest to set up. According to Paessler, PRTG can be set up in a couple of minutes. Our experience shows that while it can take a bit more than two minutes, it’s still very easy and quick to set up. Its auto-discovery process is one of the main reasons for the speed of installation. However, auto-discovery is more useful in LAN environments and most WAN setups will require that you add devices manually, which is quite easy too.

PRTG Device Overview

PRTG is a feature-rich product. For example, it comes with several different user interfaces. There’s a Windows enterprise console, an Ajax-based web interface, and mobile apps for Android and iOS. In the background, PRTG uses SNMP to poll devices and display interface utilization on chronological graphs.

PRTG is offered in two versions. There’s a free version which is full-featured but will limit your monitoring ability to 100 sensors. Each monitored parameter counts as one sensor. For example, if you monitor two interfaces on a router, it will count as two sensors. For more sensors, you need to purchase a license which starts at $1 600 for 500 sensors. A free, sensor-unlimited and full-featured 30-day trial version is available.

3. ManageEngine OpManager

ManageEngine is another well-known and respected name in the field. And the ManageEngine OpManager is a top-of-the-line product. It can run on either Windows or Linux and it is loaded with great features, It’s got, for example, an auto-discovery function that can map your network and display it on its dashboard.

ManageEngine OpManager Dashboard

As for the product’s dashboard, it is super easy to use and navigate and it has drill-down functionality. If you prefer them, there are also apps for tablets and smartphones that will let you access the system from anywhere. Overall the ManageEngine OpManager is a very polished and professional product.

A free version of the ManageEngine OpManager is available. However, it is limited and will let you monitor no more than ten devices. There are also paid versions available under either the Essential or the Enterprise plans. The first will let you monitor up to a thousand nodes while the other is good for up to ten thousand.

4. Cacti

Cacti is a free and open-source complete network monitoring tool. Its main components are a fast poller, advanced graph templates, and multiple data acquisition methods. Cacti also features user access control built right into the product. The product boasts an easy to use albeit antique-looking web-based user interface. Cacti scales very well from the smallest single device installations up to complex networks with many different WAN sites.

Cacti Screenshot

Cacti uses SNMP to fetch data and stores it in a SQL database. It is primarily written in PHP and can be modified to suit your needs. One of the product’s strongest features is its use of templates. There are built-in templates, for example, for Cisco routers that already includes most of the elements you might want to monitor on such a device. But there are not only device templates; there are also graph templates. Together, templates make configuring the software much easier. You can also build your own customized templates if suitable ones don’t already exist. Also, many device-specific templates can be downloaded from device vendor’s websites and many community-driven Cacti forums offer them for download.

5. Observium

Observium is a low-maintenance monitoring platform with auto-discovery. It supports a wide range of device types, platforms and operating systems including, among others, Cisco, Windows, Linux, HP, Juniper, Dell, FreeBSD, Brocade, Netscaler, NetApp. I doubt that you can find a WAN router that’s not supported. Observium’s primary focus is providing a beautiful, intuitive, and simple yet powerful user interface showing the health and status of your network.

Observium Port Details

The product is available in two versions. There’s the Observium Community is which available for free to everyone. This version receives updates and new features twice a year. There’s also Observium Professional which has additional features and comes with daily updates. Both versions only run on Linux.

Observium has more than just bandwidth monitoring. For instance, there’s an accounting system that will measure total monthly bandwidth usage in the 95th percentile or in total transferred bytes. It also has an alerting function with user-defined thresholds. Furthermore, Observium integrates with other systems and can pull their information and display it within its interface.

Observium users love how easy it is to set up and how it almost configures itself. Although there doesn’t appear to be a download section on Observium’s website, there are detailed installation instructions for several Linux distributions that do include the links to get the right package for each distribution. The instructions are very detailed and installing the software should be easy.

6. Zabbix

Zabbix is another free and open-source product which has a highly professional look and feel, much like you’d expect from a commercial product. But the good looks of its user interface is not its only asset. The product also boasts an impressive feature set. Zabbix will monitor most network-attached devices in addition to networking equipment. It would be a good option if you want to monitor servers in addition to your WAN circuit’s bandwidth.

Zabbix Dashboard

Zabbix uses SNMP as well as the Intelligent Platform Monitoring Interface (IMPI) for monitoring devices. You can use the software to monitor bandwidth, device CPU and memory utilization, general device health as well as configuration changes. As you can see, it does way more than simple WAN monitoring. The product also features an impressive and completely customizable alerting system. It will not only send email or SMS alerts but also run local scripts which could be used to fix some issues automatically.

7. Icinga

Icinga is yet another open source monitoring platform. It’s got a simple and clean user interface and a feature set that rivals some commercial products. Like most bandwidth monitoring systems, Icinga uses SNMP to gather usage data from devices. But one of the areas where Icinga stands out is in its use of plugins. There are tons of community-developed plugins to perform various monitoring tasks and extend the product’s functionality. And if you can’t find the right plugin for your needs, you can write one yourself and contribute it to the community.

Icinga Tactical Overview

Alerting and notification are also among Icinga’s best features. Alerts are fully configurable in terms of what triggers them and how they are transmitted. The tool also features segmented alerting. With this feature, you can send some alerts to some users and other alerts to different people. This is a great feature when you have different systems managed by different groups. In the context of WAN monitoring, you could use it to send alerts from WAN routers to each local support team, for example.

8. Zenoss Core

Zenoss Core might not be the best-known monitoring tool but it certainly deserves a spot on our list, thanks to its feature set and professional aspect. This free tool has a clean and simple interface and its alerting system is excellent. We particularly loved the multiple alerting mechanisms that will alert a second person if the first one does not respond within a predefined delay.

Zenoss Core Dashboard

Zenoss Core is one of the most complicated systems to install and set up. The process is entirely command-line driven. When used to GUI installers, configurations wizards, and auto-discovery engines, this may seem a bit archaic. However, there is ample documentation available, eliminating much of the guesswork.

Zenoss Core is a free, self-managed product with community-based support. If you need professional-grade support and extra features, you can choose between Zenoss On Premises or Zenoss Cloud, two commercial products from Zenoss. All three share the same core engine.

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