To keep an eye on the health of your network and diagnose problems that crop up, an essential activity is monitoring your bandwidth and knowing which traffic is consuming it.
Your ISP promises to provide you with a reliable pipe to the Internet of a certain volume; your chosen network hardware install is designed to provide a particular level of service within your facility. Are you getting your expected bandwidth and availability, or is something failing to deliver? Is there unexpected traffic consuming the bandwidth that you are getting?
Tools to monitor bandwidth can leverage various traffic-monitoring technologies. A host can observe all the packets passing by a particular network interface (that is, packet capture). Most managed network devices – and hosts – support SNMP, and so they can be queried to get performance statistics. If your network devices support a traffic monitoring protocol like NetFlow or sFlow, they can publish traffic data to your monitoring tool.
Which bandwidth monitoring tooling is right for you? There are several considerations. One factor is what monitoring technologies your installed hardware supports (eg, do they support SNMP? NetFlow? sFlow?). One is the size and complexity of your network; a simple tool that’s a great fit for a small office is completely inadequate for a large sophisticated network. Here we’ll look at the most popular and feature-rich free bandwidth monitoring tools.
1. SolarWinds Real-Time Bandwidth Monitor
SolarWinds makes a suite of products providing comprehensive support for network monitoring and management. Their Real-Time NetFlow Traffic Analyzer provides useful data about bandwidth for devices that support NetFlow; we discussed this tool in an earlier post on the best free NetFlow analyzers and collectors. Here we’ll focus on another free tool from SolarWinds, the Real-Time Bandwidth Monitor.
The SolarWinds Real-Time Bandwidth Monitor runs on Windows. It uses SNMP to poll multiple network interfaces in real time for their traffic statistics, and visually displays the status of a chosen interface graphically.
Once you’ve provided the IP address and SNMP parameters for the device or host, the Real-Time Bandwidth Monitor lists the interfaces there and basic data about them.
Selecting one of the interfaces provides you with a graphical display of bandwidth usage on that interface.
You can set per-interface thresholds so that the graph displays an alert when usage exceeds your chosen limits.
The Real-Time Bandwidth Monitor is a great way to see what’s going on at particular interfaces, particularly for devices that do not support NetFlow (or sFlow). The SolarWinds Real-Time Netflow Traffic Analyzer can roll up traffic by conversation, application, domain, endpoint, and protocol; the Bandwidth Monitor works from more basic metrics, so it can’t do that. But when you have devices that don’t support the traffic flow monitoring protocols, the Real-Time Bandwidth Monitor an essential tool.
(You can get also both those free tools from SolarWinds in the Bandwidth Monitoring Bundle.)
2. SoftPerfect NetWorx
Many network monitoring toolsuites assume you’re administering a large and complex network, and so provide a sophisticated array of capabilities. But in the category of bandwidth monitoring, there are many tools that go in the other direction, monitoring the bandwidth of a single PC. That’s likely too minimalistic for you, but if you have a small office, and only need to monitor one (or a few) PCs and a single router, then SoftPerfect NetWorx may be the straightforward tool you need.
NetWorx is a clean tool that will monitor the bandwidth usage on one or more PCs, or a single Mac or Linux machine; and it can also monitor bandwidth on your router to the Internet via SNMP. NetWorx is now a licensed tool, so it’s only free for 30 days, after which you must spring for a (fairly cheap) license.
Besides graphing bandwidth, NetWorx provides several tools like a speed meter and a per-user usage report.
3. ManageEngine Bandwidth Monitoring tool
ManageEngine produces a full network management suite and offers free versions of some of their tools. In our article on the best free NetFlow analyzers and collectors for Windows we looked at the ManageEngine NetFlow Analyzer which provides real-time visibility into network bandwidth and traffic patterns, when you have devices that support NetFlow. The NetFlow Analyzer displays traffic by applications, conversations, protocols, etc; it can alert you to problems, and has a range of report-generation options. Here we will focus on the Bandwidth Monitoring tool that is part of the free edition of ManageEngine OpManager.
The Bandwidth Monitoring tool leverages SNMP. It runs on Windows or Linux. The free edition support monitoring 10 devices and their interfaces.
Setting up the OpManager is a multi-step process but not overly complex. Once you provide the subnet and SNMP parameters, OpManager will scan your subnets and discover your devices. Then, from the inventory tab you can check the status of devices’ interfaces. You can view graphs and tables of network speed and bandwidth, as well as device hardware metrics, either rolled up at the device level or drilling down to a particular interface.
At the interface level you can generate reports showing bandwidth from the past 12 hours up to the past month. You can also set thresholds to receive automated alert email or SMS messages. By monitoring the gateway to your ISP, you can check your internet usage and how much bandwidth you actually receive.
The Bandwidth Monitoring tool, combined with the other features of the free version of ManageEngine OpManager, provides you with a well-rounded suite of capabilities for monitoring 10 or fewer devices on a small network.
The Paessler PRTG Network Monitor is a “batteries included” solution that monitors bandwidth utilization, the health of devices on your network, and more. The free version is limited to 100 sensors after the first month; since a sensor is an individual data stream, each device will typically require several sensors.
The PRTG Network Monitor runs on Windows. It uses SNMP, WMI, NetFlow, sFlow, and packet sniffing. Setting up the tool is a bit complex but a setup wizard and how-to video are provided.
The PRTG Network Monitor provides a well-stocked toolbox for monitoring a small network.
ntopng is an open-source web-based traffic analysis tool. The community version of ntopng is free; the professional (small business) and enterprise versions require buying a license. All versions do packet capture; the enterprise version also uses SNMP. To receive flow data ntopng depends on nProbe; a fully-functioning version of nProbe requires a paid license. Licenses are free to educational and nonprofit organizations.
ntopng’s web-based user interface rolls up data into traffic (eg, top talkers), flows, hosts, devices, and interfaces.
ntopng is a richly-featured open source traffic and bandwidth monitoring tool.
Making a choice
Several good free options are available to monitor the bandwidth of your network. Picking the appropriate one will depend on your installed network hardware, the size and sophistication of your network, and how you expect it to grow.
“Network cables” by pxhere, licensed under CC0.