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.
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 clients that increase destination IP with -P via –incr-dstip
- 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
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)
Operating systems supported by Iperf3
- Windows, Linux, Android, macOS X, FreeBSD, OpenBSD, NetBSD, VxWorks, Solaris
Download Iperf3
Iperf2 vs Iperf3
| Featured | Iperf 2 | Iperf 3 |
| Traffic types | ||
| TCP traffic | Y | Y |
| UDP traffic | Y | Y |
| SCTP traffic | N | Y |
| IPv4 | Y | Y |
| IPv6 | Y | Y |
| Multicast traffic (including SSM) | Y | N |
| TCP connect only | Y | N |
| Layer 2 checks | Y | N |
| Output options | ||
| Human format | Y | Y |
| JSON output | N | Y |
| CSV (basic only) | Y | N |
| Hide IP addresses in output (v4 only) | Y | N |
| Client side server reports | N | Y |
| Traffic profiles | ||
| Fair queue rate limiting | Y | Y |
| Write rate limiting | Y | Y |
| Read rate limiting (TCP) | Y | N |
| Bursts | Y | Y |
| Isochronous (video) TCP/UDP | Y | N |
| Reverse roles | Y | Y |
| Bidirectional traffic | Y | Y |
| Full duplex same socket | Y | N |
| TCP bounceback w/optional working load(s) | Y | N |
| Low duty cycle traffic with server side stats | Y | N |
| TCP_NOTSENT_LOWAT with select() (using the –tcp-write-prefetch option) | Y | N |
| TCP near congestion (experimental) | Y | N |
| Metrics | ||
| Throughput | Y | Y |
| Responsiveness per second (RPS) | Y | N |
| UDP packets (total/lost) | Y | Y |
| UDP Jitter | Y | Y |
| Packet latencies UDP | Y | N |
| TCP/UDP frame/burst latencies | Y | N |
| Write-to-read latencies TCP | Y | N |
| Network power (latency/throughput) | Y | N |
| InP – Bytes in queues (Little's law) | Y | N |
| TCP CWND | Y | N |
| TCP retries | Y | Y |
| TCP RTT | Y | Y |
| Send side write delay histograms | Y | N |
| UDP packets per second | Y | N |
| Latency histograms | Y | N |
| TCP connect times | Y | N |
| TCP response per interval | Y | N |
| Sum only output | Y | N |
| Other | ||
| Multi-threaded design | Y | N |
| Parallel -P technique | Threads | Processes |
| Real-time scheduling | Y | N |
| -t support for server | Y | N |
| TAP virtual interface support (receive only) via –tap-dev | Y | N |
| CPU affinity | N | Y |
| Zero copy | N | Y |
| IPv6 Flow Labels | N | Y |
| –omit option (skip first samples per time in seconds) | N | Y |
| Incr dst ip option with -P | Y | N |
| Incr dst ip option with -P | Y | N |
| Incr dst port option with -P | Y | N |
| Incr src port option with -P | Y | N |
| Device or interface binding | Y | Y |
| Source port binding | Y | N |
| Scheduled tx start time | Y | N |
| Delay tx start time | Y | N |
| User password | N | Y |
| Permit keys | Y (TCP only) | N |
| Stateless UDP | Y | N |
| Python framework (asyncio) | Y (flows) | N |
| Testing WiFi thru 100G | Y | N/a |
| Scaling to 1000+ threads | Y | N/a |
