ESnet’s iperf3 Tool Helps Comcast Meet Customer Demand During COVID-19 ISP Surge

April 21, 2020

Contact: Kathy Kincade,, +1 510 495 2124

A network diagnostic and performance measurement tool developed by engineers at the U.S. Department of Energy’s (DOE’s) Energy Sciences Network (ESnet) and Lawrence Berkeley National Laboratory (LBNL) is being used by Comcast to fine-tune the largest residential Internet network in the United States and help ensure its services remain up and running at top speed during the COVID-19 crisis.

“We are seeing an unprecedented shift in network usage, but it’s within the capability of our network,” Comcast states on its COVID-19 Network Update webpage.

Prompted by shelter-in-place orders across the U.S. and the world in recent months, extraordinary demand is being placed on residential Internet service providers (ISPs) as people increasingly rely on home-based Internet connections for entertainment, education, shopping, and work.

ESnet’s open-source iperf3 tool is helping Comcast meet this challenge by giving them the ability to make timing and buffering changes across their network in real-time. Originally developed in 2009 as part of the perfSONAR toolkit, iperf3 is designed to measure the available network bandwidth between two hosts on an IP network. It supports tuning of features related to timing, protocols, and buffers; for each test it reports the measured throughput, loss, and other parameters.

At present, Comcast – which is seeing a 30% uptick in network traffic since the country’s shelter-in-place orders took effect – is using iperf3 to run 700,000+ diagnostic speed tests per day. This helps them engineer the network for peak capacity and better handle spikes and shifts in usage patterns.

“Comcast is one of the largest ISPs in the world, and they are using iperf3 – part of their normal troubleshooting workflow – to make sure their network is delivering the performance that is required in this situation,” said Bruce Mah, a software engineer in ESnet's Software Engineering Group who works with Comcast as part of their open-source relationship.

ESnet, a DOE Office of Science user facility managed by LBNL, is the fastest network in the world dedicated to science. It supports a multi-100Gbps fiber optic backbone that connects the DOE’s national laboratory system and experimental facilities with research and commercial networks around the globe.