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How to do an iPerf Test: Assessing Your Network Performance

In today’s interconnected world, having a high-performing and efficient network is crucial. One useful tool for checking and improving this is iPerf. Throughout this blog, we will unravel what iPerf is, how to use it, and how it can be used to test the performance of your network. We will guide you on how to prepare for an iPerf test and highlight the necessary tools and software. Among them, we will elaborate on a handy device, NetAlly’s Test Accessory, a pocket iPerf server that significantly simplifies network performance testing.

What is iPerf and How Do You Use It

iPerf is a freely available open-source network performance testing software program that allows engineers to measure the performance of their network infrastructure. It involves generating network traffic between two endpoints, a client and a server, and measures the available bandwidth, providing valuable insights into the network’s capabilities and helping identify areas for improvement. The iPerf test measures upload and download speed.

During an iPerf test, the client sends a predefined amount of data to the iPerf server, and the server measures the time it takes for the data to be transmitted. The test can be conducted upstream only, downstream only, or bi-directionally (“upstream/downstream”). Based on this information, iPerf calculates the network’s performance metrics, which can then be analyzed and interpreted by network engineers. For the best, realistic representation, it is important to conduct the speed test during working hours when typical network traffic is present (however, users are advised to limit test duration to avoid disruption of actual network traffic!) The iPerf test can generate and measure either TCP traffic (e-mail, internet browsing) or UDP traffic (video streaming).

The Utility of iPerf Testing in Network Engineering

iPerf testing is a useful tool for network engineering as it allows engineers to gain a better understanding of a network’s performance characteristics. By conducting these tests, engineers can identify bottlenecks, detect network congestion, and pinpoint areas where network performance can be optimized. When network issues arise, engineers can use iPerf to isolate the problem and determine its root cause. By comparing the test results with baseline measurements, engineers can quickly identify deviations and take appropriate actions to resolve the issue.

iPerf testing enables engineers to predict and proactively address potential issues before they impact end-users. By regularly testing network performance using iPerf, engineers can identify trends and patterns that may indicate future problems.

Preparing for an iPerf Test

When it comes to conducting an iPerf test, there are a few important steps to take to ensure accurate and reliable results. In addition to gathering the necessary equipment and software, setting up your testing environment properly is crucial.

Necessary Equipment and Software

Before diving into the iPerf test, it is essential to gather the necessary equipment and software. To establish a client-server connection, you will need at least two devices, typically two PCs or servers. Having multiple devices equipped with iPerf software on your network allows you to measure performance across different network segments.

Once you have the devices ready, the next step is to download and install the iPerf software. You will have to familiarize yourself with the various command line options for configuring and executing tests. If you don’t want to go through the hassle of installing software on local servers or PCs (some organizations limit the type of software that can be installed), you can use NetAlly’s Test Accessory. This handy iPerf tool already includes the iPerf server software, comprehensive guidelines, and a user-friendly interface. Importantly, it can be powered via PoE; some users deploy multiple Test Accessories “always on” across their infrastructure, ready for testing anytime as needed.

Setting Up Your Testing Environment

Now that you have the necessary equipment and software, it’s time to set up your testing environment.

The first step in setting up your testing environment is to ensure that all devices are connected to the same network or are reachable via a routed connection. Depending on the capabilities of your devices, connect via ethernet or WiFi. The Test Accessory, for instance, is mostly used for wired speeds up to 1 Gbps, but can be targeted by a WiFi iPerf client for “WiFi to Wired” testing.

By taking the time to gather the necessary equipment, install the iPerf software if necessary, and configure your testing environment properly, you can ensure that your iPerf test provides reliable and valuable insights into your network’s performance.

NetAlly’s pocket-sized Test Accessory is an independent iPerf server that simplifies network performance testing by providing comprehensive and precise measurement of TCP/UDP throughput. Its real value lies in its ability to automate the often complex process of setting up and configuring an iPerf server and using the appropriate commands for test execution. With the Test Accessory, you only have to connect it to an ethernet port in your network and you’re ready to test.

This rugged accessory is designed for constant operation. The device can easily be plugged into any ethernet port with Power over Ethernet (PoE) for 24/7 availability without power concerns, making it ready for a test at all times. It also conducts simple network port verification tests upon connection,  validating PoE, link, DHCP, DNS, router reachability, and Internet access, and sends these test results directly to Link-Live™, NetAlly’s collaboration, reporting and analysis platform. This iPerf tool helps in maintaining optimal network health by validating throughput to prevent potential issues. It facilitates remote site testing irrespective of subnets or local resources.

Overall, the Test Accessory by NetAlly greatly simplifies the performance testing and troubleshooting process with its comprehensive functionality, ease of use, and constant readiness. Check out the video to understand how to conduct a Wi-Fi to wired iPerf test using the NetAlly AirCheck G3 and Test Accessory.

When iPerf is not enough

As we’ve described, iPerf remains a useful tool in the network professional’s kit. However, there are some limitations. One is that results can be impacted by the capabilities of the device running the tests, sometimes limiting the amount of traffic that can be effectively generated to less than the available bandwidth of the network infrastructure. Additionally, iPerf does not test latency, and jitter is calculated, not measured.

When critical links or service provider SLA’s need to be absolutely verified, NetAlly’s Performance Test app (on EtherScope® nXG, CyberScope®, and LinkRunner® 10G) provides full line-rate testing to 10Gbps, measuring jitter and latency, and verifies end-to-end QoS.


iPerf testing is a useful capability for anyone who wants to maintain an efficient and reliable network. It provides insights about your network’s performance, pointing out any potential issues that could disrupt its operation. With the help of devices like NetAlly’s Test Accessory, conducting an iPerf test becomes an even simpler and more efficient process. Whenever your network falls short of expectations, instead of guessing and worrying, rely on an iPerf test. With its precise metrics and comprehensive analysis, it paves the way for strategic improvements and steady performance.

Author Bio –
Product Manager – Wireless

Julio Petrovitch is a product manager at NetAlly, plus a certified CWNA/CWAP/CWDP/CWSP. He’s worked with network design, testing and validation for more than 15 years. Throughout he’s career he has had the opportunity to work with multiple networking technologies, including POTS, DSL, Copper/Fiber Ethernet, Wi-Fi, Bluetooth, and BLE.