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SolarWinds Network Performance Monitor (NPM) vs Nagios XI – Comparative Review

Network Monitoring is an important task for most of today’s network and system administrators. Distributed systems and cloud-based hosting are such that we are further away than ever from the machines we take care of. Consequently, we must use specialized tools to monitor them. And while there are plenty of different types of tools available, it seems like the all-in-one monitoring solution is the best option. It will let you monitor bandwidth utilization as well as servers and other systems. Many such tools are available on the market but today, we’ll have a closer look at two of them, the SolarWinds Network Performance Monitor and Nagios XI. We’ll compare the two products with the goal of helping you figure out which one is best adapted to your specific needs.

Before we get to the essence of this post, we’ll explore network monitoring. Knowing more about the subject will help us better understand the differences and similarities between the two products. After that, we’ll talk about SNMP, the most-used monitoring technology. We’ll do our best to describe what it is, where it’s coming from, and how it works. We’ll then have a look at what other monitoring technologies are available besides SNMP. As you’ll see, there are quite a few more. After that, we’ll have a look first at the SolarWinds Network Performance Monitor, its main features, pricing structure, and pros & cons, followed by a similar look at Nagios XI. Finally, we’ll compare both products to try to give you a better understanding of what their similarities and differences are and we’ll conclude by giving you our honest opinion about the two products.

About Network Monitoring

Defining monitoring can be a difficult task as it seems that everyone has s own idea of what it is, or at least what it should be. To make matters even worse, there are several types of monitoring. Let’s have a look at each one, starting with the most basic: ping (or up/down) monitoring. This crude type of monitoring uses ping to verify that each monitored device is operational. Monitoring is accomplished by using the ping command in the background to verify that each monitored host is responding. Not much information about the actual health of the monitored device can be obtained.

Network Bandwidth monitoring is another common type of monitoring. In fact, it’s probably the most common type. Most of the time, this type of monitoring tool uses the Simple Network Management Protocol to remotely read interface counters from monitored devices. It can then compute the average bandwidth utilization of their interfaces. This is often used for monitoring bandwidth-limited segments of a network such as WAN links. What you get from these systems is a quantitative view of the traffic. It will show any network congestion and tell you when it started and when it stopped but it won’t give you a clue as to what its cause is.

For that, you the next type of monitoring tools: network traffic analyzers. These tools pick up where the previous one left off. They’ll perform some basic traffic analysis to find out what is consuming bandwidth. You can use them to find out which users, computers or applications are using the most bandwidth. You get a qualitative view of network traffic.

Another type of monitoring tool that we often call server or system monitor goes even deeper and reads the operational metrics of the monitored devices. One typically uses that kind of tool to monitor any device from routers and switches to servers and databases. This type of tool typically provides data such as CPU and memory load, disk space and any other interesting data which can be collected and displayed.

The Simple Network Management Protocol (SNMP)

Let’s have a quick look at the Since the Simple Network Management Protocol, After all, it is the most-used monitoring technology. Don’t let its name fool you, though. This protocol is anything but simple. SNMP-enabled devices can let a management station—or, in the case of monitoring, a monitoring tool—read and/or set a number of operational parameters. SNMP is often referred to as an agentless monitoring technology. However, despite the fact that it rarely requires installing any extra software on the monitored device, SNMP-enabled devices do run an agent on each monitored equipment. It is usually built into the operating system or firmware which is why it is not referred to as an agent.

From a monitoring perspective, understanding how SNMP monitoring works is relatively easy. Without going too technical, let’s have a look. At regular intervals—5 minutes is a common value—the SNMP monitoring software polls each device by sending it a request for a specific parameter it wants to read. The only security offered by the protocol is a “community string” which can be compared to a crude authentication mechanism. The monitored device validates the community string and, if it matches, returns the requested value. This is a highly simplified version of the process so forgive me if I left out important parts of the protocol. Our goal is not to provide an SNMP tutorial but rather an understanding of how SNMP monitoring works.

Let’s have a short example where a monitoring tool is used to monitor the bandwidth usage of a router interface facing a WAN circuit. Two specific SNMP parameters are of interest, the bytes in and bytes out counters of the interface. They are read on a regular basis—let’s say every five minutes—and stored in a file or a database. That’s the hard part, the rest is just math. The monitoring tool subtracts the previous value of the counters from the current one, giving the number of bytes transferred during the five-minute interval. It then divides these numbers 300, the number of seconds in five minutes, giving the number of bytes per second and divides this by eight to get the number of bits per second. The resulting values are stored in a database or plotted on a graph showing its evolution over time.

Other Monitoring Techniques

SNMP is, it is far from being the only—perhaps even the best—monitoring technology. Many other technologies are available, depending on what type of device you are monitoring and what information you are trying to collect from it. Let’s have a quick look.

The Windows Management Instrumentation, or WMI, is a Windows-specific protocol. It is, to a certain extent, an evolution of SNMP. Both have a similar purpose—managing and monitoring systems remotely—but its operation is different. It is more secure, more flexible and can provide more information. It has one major drawback, though. WMI is only available on Windows hosts.

WBEM is an acronym for Web-Based Enterprise Management. It is an open standard for the remote management and monitoring of systems. WMI and WBEM are quite similar. WMI is Microsoft’s proprietary implementation of WBEM, an open standard. This protocol is typically used for monitoring non-Windows hosts such as Linux servers, for example.

The last type of monitoring we want to discuss is called agent-based monitoring. This popular technique relies on a local agent running on the monitored system. Contrary to the other methods, the monitoring agent is not built into the operating systems. It is supplied by the monitoring tool’s vendor. It is perfectly adapted to the tool and it often permits the monitoring of metrics which would not be available otherwise. It has a few drawbacks, though. Of course, agent-based monitoring requires that an agent is installed on monitored systems. That agent can have an impact on the monitored system since it’s using part of its resources.

1. SolarWinds Network Performance Monitor (Free Trial)

SolarWinds, the maker of the Network Performance Monitor has been around for about 20 years and it enjoys a solid reputation for having made some of the best network and system administration tools. Many of the company’s products have received rave reviews and are considered among the very best in their respective fields. And to make it even better, SolarWinds is also famous for its free tools, smaller tools which address a specific need of network administrators. Two good examples of those free tools are the Real-time Bandwidth Monitor and the Kiwi Syslog Server.

Back to the Network Performance Monitor, it is primarily an SNMP bandwidth monitoring although it can do a whole lot more either through built-in functionalities or by combining it with other tools from SolarWinds. At its core, the product offers comprehensive fault monitoring and performance management using SNMP and it is thereby compatible with most equipment. The tool’s NetPath feature lets you view the critical network path between any two monitored points on your network, In addition, it can also auto-generate intelligent network maps.

SolarWinds NPM - Network Summary

Other strengths of the product include advanced alerting and the tool’s PerfStack performance analysis dashboard. Another exclusive feature is the Network Insights functionality which allows for complex device monitoring. The tool can also monitor Software Defined Networks (SDN) and has built-in Cisco ACI support as well the ability to monitor wireless networks and to generate network performance baselines.

The SolarWinds Network Performance Monitor is highly scalable and it can be used on any network from the smallest to the largest. Some of the optional features include scalability engines, high availability and an enterprise operations console which lets you consolidate the data from multiple NPM instances into one enterprise-grade dashboard.

SolarWinds NPM Wireless Summary

The SolarWinds Network Performance Monitor has a rather simple pricing Structure. Licensing is based on the number of monitored elements. Five licensing tiers are available for 100, 250, 500, 2000, and unlimited elements at prices ranging from $2 955 to $32 525, including the first year of maintenance. If you’d rather give the tool a test run before committing to a purchase, a free, element-unlimited 30-day trial version can be obtained.

Pros & Cons Of NPM

To give you an idea of what users think of it, here are the pros and cons of the SolarWinds Network Performance Monitor as reported in user reviews of the product.


  • The web interface is completely customizable allowing different members of your IT team to use a view that suits them. For instance, system administrators can use a view that focuses on VMware hosts while the network administrator’s view focuses on network switches and traffic.
  • NPM has excellent and easily configurable alerts. You could even create an alert to notify you when a device that is supposed to remain disconnected from the network connects. The possibilities are endless.
  • You can create device pollers combined with custom metering Which can virtually return any information you need.


  • Email configuration, while highly flexible and customizable, could be easier.
  • The NetFlow Traffic Analyzer (a qualitative network analysis module) is not built into the product and must be purchased separately, increasing the product’s price.
  • Some users have complained about the lack of filtering and searching options on syslogs and alerts.

2. Nagios XI

Nagios XI is an enterprise-grade server and network monitoring software which provides comprehensive application, service, and network monitoring in a central solution. The product is a direct descendant of Nagios Core, a related free and open-source product. In fact, both use the same base engine. However, they are two widely different products that should not be confused. Today, we’re only talking about Nagios XI. The tool lets you monitor all mission-critical infrastructure components such as applications, services, operating systems, network protocols, systems metrics, and network infrastructure.

Nagios XI Dashboard Screenshot

Nagios XI’s powerful dashboards provide at-a-glance access to powerful monitoring information and third-party data. Various views provide users with quick access to the information they find most useful. The tool’s GUI is highly customizable and its layout, design, and preferences can be modified on a per-user basis, giving your team members the flexibility they want.

Nagios XI is very easy to use, thanks to its integrated web-based configuration interface which lets administrators manage monitoring configuration, system settings, and more. The platform also offers configuration wizards to guide users through the process of monitoring new devices, services, and applications without having to understand complex monitoring concepts.

Other interesting features of Nagios XI include automated and integrated trending as well as capacity planning graphs allowing organizations to plan for infrastructure upgrades before outdated or overused systems catch them by surprise. Alerts can be sent to IT staff members, business stakeholders, and even end-users via email or mobile text messages.

Nagios XI Home Dashboard

Nagios XI will only run on CentOS or RedHat Enterprise Linux. It could, of course also run in a virtual Linux machine on a Windows host but it is essentially a Linux piece of software. A MySQL database is also required for its operations.

Nagios XI is available in a Standard Edition and an Enterprise Edition. The Enterprise Edition offers additional functionality and includes features designed to aid in large-scale configuration, forecasting, and scheduled reporting. Each license includes twelve months of maintenance (upgrade entitlements) and email support. Licensing is based on the number of monitoring hosts and starts at $1 995 for the Standard Edition and $3 495 for the Enterprise Edition. If you’d like to give the product a test run, a free 60-day trial version is available.

Pros & Cons of Nagios XI

Just like we did with the SolarWinds NPM, we’ve compiled user commentaries Nagios XI PRTG and here are the pros and cons they reported


  • Nagios XI is easy to set up and configure (especially when compared to Nagios Core)
  • Hundreds of third-party add-ons provide for monitoring of virtually all applications, services, and systems, both in-house or commercial.
  • Since it shares the same core as the free and open-source version of Nagios, it supports all community developed add-ons making for an impressively broad array of monitoring possibilities.


  • Nagios XI won’t run on Windows. This could stop some admins with no Linux background from even considering the product. And although it could run in a VM on Windows, it adds some complexity to the setup.
  • Some users have complained of a somewhat antiquated look and feel. However, the GUI is very functional.
  • Customization options can get in the way of upgrade.

Comparing Both Products

Comparing the SolarWinds Network Performance Monitor and the Nagios XI is harder than it may look. They are at the same time very similar and totally different. In terms of operability and usability of the user Interface, the SolarWinds Netwotk Performance Monitor stands out as a clear winner next to Nagios XI’s antiquated GUI.

But there’s more to a monitoring tool than its user interface. When it comes to shear monitoring capabilities, Nagios XI offers more in terms of capabilities than a Nagios installation. In summary, out of the box, NPM trumps Nagios XI.

Although we wouldn’t recommend picking a tool solely on price, this is another place where both tools differ widely. Although the SolarWinds Network Performance Monitor is somewhat more expensive than Nagios XI, they are in a comparable range.

What Do We Think?

We’d love to be able to tell you that one of NPM and Nagios XI is a clear winner over the other but it is not that simple. There is one factor which is more important than all other when choosing a monitoring solution: your needs. The best product for anyone will always be the one which as features they need, regardless or its price. In the battle between NPM and Nagios XI, a user with a wireless monitoring and management needs will likely choose the SolarWinds product. On the other hand, if you have a very specific monitoring need which is addresses by one of Nagios XI’S add-on, then it will certainly get your vote.

I tend to prefer the SolarWinds Network Performance Monitor but I have to admit that I’m probably biased towards it. This is simply due to the fact that it is a product that I know and have used for years and I know exactly what it can do and how to do it. If you’re new to both products, your best bet is possibly to try them both before making a final decision. With both vendors offering a free trial of their respective product, this should be easy.

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