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@@ -0,0 +1,154 @@ +**Iperf 2 - Network testing tool** *(based from 2.0.5)* + +This document is not done. RJM 8/24/2021 + +Man page: https:://iperf2.sourceforge.io/iperf-manpage.html + +--- +Iperf 2, this program, is different from the iperf 3 found +at https://github.com/esnet/iperf + +Each can be used to +measure network performance, however, **iperf 2 and iperf 3 DO NOT interoperate.** +They are completely different implementations with different strengths, capabilities and +different options. Iperf 2 took its code base from the original iperf code (that stalled at 2.0.5.) +Iperf 3 is a rewrite from scratch. + +Both Iperf 2 (now at 2.1.4) and iperf 3 are both under active development (as of mid-2021) + +Iperf 2 vs 3 table: https://iperf2.sourceforge.io/IperfCompare.html + +***See the end of the file for license conditions*** + +--- +Iperf 2.1.4 has many user visible changes since 2.0.13 and even more since +2.0.5 The below describes many of these user visible changes with +a focus on 2.1.4 compared to 2.0.13 + + +--- +**Iperf 2 new metrics** + +**NetPwr** + + Network power: The network power (NetPwr) metric originates from Kleinrock and Jaffe circa 1980. + It is a measure of a desirable property divided by an undesirable property. + It is defined as throughput/delay. For TCP transmits, the delay is the sampled RTT times. + For TCP receives, the delay is the write to read latency. For UDP the delay is the + packet end/end latency. + + Note, one must use -i interval with TCP to get this as that's what sets the RTT sampling rate. + The metric is scaled to assist with human readability. + +**InP** + + The InP metric is derived from Little's Law or Little's Lamma. LL in queuing theory is a + theorem that determines the average number of items (L) in a stationary queuing system + based on the average waiting time (W) of an item within a system and the average number + of items arriving at the system per unit of time (lambda). Mathematically, + it's L = lambda * W. As used here, the units are bytes. The arrival rate is + taken from the writes. + +--- + +**Iperf 2 Enhanced Reports** + +Much of the new outputs require **-e** for **--enhanced-reports**. This is supported on both the client and server + +**Client side (TCP)** + +***Write:*** the number of socket write calls +***Err:*** the number of write syscalls that returned with a non fatal error +***Rtry:*** The sampled TCP retry value +***RTT:*** the sampled TCP round trip time +***CWND:*** the sampled TCP congestion window +***NetPwr:*** the computed network power (using RTT) + +**Server side (TCP)** + +***Burst Latency:*** The avg/min/max/stdev message latencies +***cnt:*** the number of bursts or write messages +***size:*** the average burst or write size +***inP:*** the computed bytes in flight per Little's law +***NetPwr:*** the computed network power (using burst arrival rates) +***Reads:*** histogram of read sizes + + +**Client side (UDP)** + +***Write:*** the number of socket write calls +***Err:*** the number of write syscalls that returned with a non fatal error +***PPS:*** The sampled packets per second (computed as a derivative) + +**Server side (UDP)** + +***Write:*** the number of socket write calls +***Err:*** the number of write syscalls that returned with a non fatal error +***PPS:*** The sampled packets per second (computed as a derivative) + + + + + --- + +* configure '**--enable-fast-sampling**' + + This configuration causes the iperf binary to support units + of microseconds. It casues iperf to use four units of precision + in it's timing interval output, i.e. 1e-4, as one example + +> iperf -c 192.168.1.64 -n 4 -C +> ------------------------------------------------------------ +> Client connecting to 192.168.1.64, TCP port 5001 +> TCP window size: 85.0 KByte (default) +> ------------------------------------------------------------ +> [ 1] local 192.168.1.133 port 56568 connected with 192.168.1.64 port 5001 +> [ ID] Interval Transfer Bandwidth +> [ 1] 0.0000-0.0172 sec 4.00 Bytes 1.86 Kbits/sec + +* '**--trip-times**' on the client + + This option indicates to iperf a few things. First, that the user + has syncrhonized the clients' and servers' clocks. A good way to do + this is using Precision Time Protocol and a GPS atomic clock as a + reference. This knowledge allows iperf to use many time stamps + to be sender based, i.e. taken from the sender's write timestamp + (which is carried in the payloads.) + + The connect message on both the server and the client will indicate + that '--trip-times' has been enabled. + + Both UDP an TCP support '--trip-times' + +> iperf -c 192.168.1.64 --trip-times +> ------------------------------------------------------------ +> Client connecting to 192.168.1.64, TCP port 5001 +> TCP window size: 85.0 KByte (default) +> ------------------------------------------------------------ +> [ 1] local 192.168.1.133 port 56580 connected with 192.168.1.64 port 5001 (trip-times) +> +> iperf -s +> ------------------------------------------------------------ +> Server listening on TCP port 5001 +> TCP window size: 128 KByte (default) +> ------------------------------------------------------------ +> [ 1] local 192.168.1.64%enp2s0 port 5001 connected with 192.168.1.133 port 56580 (MSS=1448) (trip-times) (sock=4) (peer 2.1.4) on 2021-08-22 11:12:08 (PDT) + + + + +---------------------------------------------------------------------- +This file is part of iperf 2. + +Iperf 2 is free software: you can redistribute it and/or modify +it under the terms of the GNU General Public License as published by +the Free Software Foundation, either version 3 of the License, or +(at your option) any later version. + +Iperf 2 is distributed in the hope that it will be useful, +but WITHOUT ANY WARRANTY; without even the implied warranty of +MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +GNU General Public License for more details. + +You should have received a copy of the GNU General Public License +along with iperf 2. If not, see <https://www.gnu.org/licenses/>.
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