Iperf2 vs Iperf3 – Network Performance Measurement

Iperf is a network performance measurement and optimization tool.

The iperf application is a cross-platform program can provide standard network performance metrics. Iperf comprises a client and a server that can generate a stream of data to assess the throughput between two endpoints in one or both directions.

iperf2

A typical iperf output includes a stamped time report of the amount of data transported and the measured throughput.

Iperf2

Iperf2 is a network throughput and responsive measurement tool that supports TCP and UDP. One of its goals is to keep the iperf codebase functioning on various platforms and operating systems.

It is a multi-threaded architecture that grows in proportion to the number of CPUs or cores in a system with which it can get and report network performance using high- and low-impact strategies.

Features of Iperf2

  • Supports smaller report intervals (100 us or greater, configure –enable-fast sampling for high-precision interval time output)
  • Supports SO_RCVTIMEOUT for report servers regardless of no package
  • Support SO_SNDTIMEO when sending so that socket writes won’t block beyond -t or -i
  • Supports SO_TIMESTAMP for kernel-level package timestamps
  • Supports end/end latency in mean/min/max/stdev (UDP) format (-e required) (assuming client and server clocks are synchronized, e.g. with Precision Time Protocol to  OCXO  per Spectracom oscillator)
  • Supports TCP-level limited flows (via -b) using a simplified token bucket
  • Supports packets per second (UDP) over pps as units, (e.g. -b 1000pps)
  • Show PPS in client and server (UDP) reports (-e required)
  • Supports real-time schedulers as command-line options (–real-time or -z, assuming proper user rights)
  • Display target loop time in the initial client header (UDP)
  • Add local support of ipv6 links (eg. iperf -c fe80::d03a:d127:75d2:4112%eno1)
  • UDP ipv6 payload defaults to 1450 bytes per one ethernet frame per payload
  • Support isochronous traffic (via –isochronous) and frame burst with variable bit rate (vbr) traffic and frame id
  • SSM multi-cast support for v4 and v6 uses -H or -ssm-host, ie.  iperf -s -B ff1e::1 -u -V -H fc00::4
  • Latency histograms for packets and frames (e.g. –udp-histogram=10u.200000, 0.03, 99.97)
  • Support for timed delivery starts per –txstart-time <unix.epoch time>
  • Support for clients that increase destination IP with -P via –incr-dstip
  • Support for varying the load is offered using the normal distribution of logs around the mean and standard deviation (per -b <mean>,<stdev>),
  • Honor -T (ttl) for unicast and multicast
  • UDP uses a 64-bit sequence number (although it still operates with 2.0.5 which uses a seq number  of 32b.)

Iperf2 supported operating systems

  • Linux, Windows 10, Windows 7, Windows XP, macOS, Android, and some OS set-top boxes.

Download Iperf2

Iperf2 Windows v2.1.8

Iperf2 Linux v2.1.8

Iperf3

The Iperf3 application is a rewrite of iperf from scratch to create a smaller and simpler codebase.

iPerf3 is a tool for measuring the maximum possible bandwidth on an IP network in real-time. It allows you to fine-tune various timings, buffers, and protocols (TCP, UDP, SCTP with IPv4 and IPv6).  And it will also provide reports of bandwidth, losses, and other metrics for each test.

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Features of Iperf3

  • TCP and SCTP (Measure bandwidth, Report MSS/MTU size and observed read size, Support for TCP window size over socket buffer).
  • UDP (Client can create UDP flow from specified bandwidth, Measure packet loss, Measure delay jitter, Capable multicast)
  • Both the client and the server can have several simultaneous connections (-P option).
  • The server handles multiple connections, rather than stopping after a single test.
  • Can run for a specified time (option -t), rather than any amount of data to be transferred (option -n or -k).
  • Periodic print, medium bandwidth, jitter, and loss reports at specific intervals (option-i).
  • Run the server as a daemon (-D option)
  • Use representative flows to test how link layer compression affects achievable bandwidth (-F option).
  • A server receives one client simultaneously (iPerf3) and multiple clients simultaneously (iPerf2)
  • Ignore TCP slow-start (-O option).
  • Set the target bandwidth for UDP and (new) TCP (option -b).
  • Set IPv6 flow label (-L option)
  • Set the congestion control algorithm (-option -C)
  • Use SCTP instead of TCP (–sctp option)
  • The output is in JSON format (-J option).
  • Disk read test (server: iperf3 -s / client: iperf3 -c testhost -i1 -F filename)
  • Disk write test (server: iperf3 -s -F filename / client: iperf3 -c testhost -i1)

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