iperf3 vs TRex

iperf3 is a free command-line network measurement tool that reports achievable IP-network bandwidth, throughput, loss, and related results. It includes client and server functions for TCP, UDP, and SCTP tests, with adjustable timing, protocol, and buffer settings. Client or server output can be emitted as JSON, including line-delimited JSON for real-time parsing, and a library version can be embedded in other programs. The project uses a three-clause BSD license and lists Ubuntu Linux, FreeBSD, and macOS as its officially supported platforms. Windows is not officially supported; its FAQ points users with Windows problems toward iperf2. ESnet supplies source distributions rather than binary packages and recommends checking SHA256 checksums. iperf3 began as a perfSONAR bandwidth tester, its primary user base. It is not backwards compatible with the original iperf. Version 3.22 was released September 29, 2026.

TRex is an open source traffic generator for benchmarking platforms with realistic network traffic. It produces Layer 3–7 traffic in stateless, stateful, and advanced stateful modes. Stateless mode supports multiple streams, packet-field changes, and per-stream or per-group statistics, latency, and jitter. Advanced stateful mode emulates Layer 7 traffic over scalable TCP and UDP flows. Emulation includes ARP, IPv6, ND, MLD, IGMP, ICMP, DOT1X, DHCPv4, DHCPv6, and DNS. TRex offers Python automation APIs and a console interface; stateless functions can also be used through JSON-RPC. The manual describes it as a Linux application using DPDK and Linux kernel modules, intended for COTS x86 servers. The site says one server can scale up to 200 Gb/sec. It can run in a virtual machine or Docker for low-performance, low-footprint use, but virtual switches can limit throughput and virtual-machine latency results are not accurate. TRex is free, with hardware and NIC requirements. The GUI monitoring application TRexViewer is supported only on Windows.