Iperf download

I am often asked to measure the bandwidth of a network path. Many users test this using a simple HTTP download or with speedtest.net. Unfortunately, any test using TCP will produce inaccurate results, due to the limitations of a session-oriented protocol. TCP window size, latency, and the bandwidth of the return channel (for ACK messages) all affect the results. The most reliable way to measure true bandwidth is with UDP. That’s where my friends iperf and bwm-ng come in handy.iperf is a tool for measuring bandwidth and reporting on throughput, jitter, and data loss. Others have written handy tutorials, but I’ll summarise the basics here.iperf will run on any Linux or Unix (including Mac OSX), and must be installed on both hosts. Additionally, the “server” (receiving) host must allow incoming traffic to some port (which defaults to 5001/UDP and 5001/TCP). If you want to run bidirectional tests with UDP, this means you must open 5001/UDP on both hosts’ firewalls.iptables -I INPUT -p udp -m udp --dport 5001 -j ACCEPTA network path is really two paths – the downstream path and the upstream (or return) path. With iperf, the “client” is the transmitter and the “server” is the receiver. So we’ll use the term “downstream” to refer to traffic transmitted from the client to the server, and “upstream” to refer to the opposite. Since these two paths can have different bandwidths and entirely different routes, we should measure them separately.Start by opening terminal windows to both the client and server hosts, as well as the iperf man page. On the server, you only have to start listening. This runs iperf as a server on the default 5001/UDP.root@server:~# iperf -s -u------------------------------------------------------------Server listening on UDP port 5001Receiving 1470 byte datagramsUDP buffer size: 124 KByte (default)------------------------------------------------------------The server will output test results, as well as report them back to the client for display.On the client, you have many options. You can push X data (-b) for Y seconds (-t). For example, to push 1 mbit for 10 seconds:root@client:~# iperf -u -c server.example.com -b 1M -t 10------------------------------------------------------------Client connecting to 172.16.0.2, UDP port 5001Sending 1470 byte datagramsUDP

Report:[ ID] Interval Transfer Bandwidth Jitter Lost/Total Datagrams[ 3] 0.0-10.0 sec 1.11 MBytes 933 Kbits/sec 0.134 ms 1294/19533 (6.6%)To find the total packet size, add 28 bytes to the datagram size for UDP+IP headers. For instance, setting 64-byte datagrams causes iperf to send 92-byte packets. Exceeding the MTU can produce even more interesting results, as packets are fragmented.iperf provides final throughput results at the end of each test. However, I sometimes find it handy to get results as the test is running, or to report on packets/second. That’s when I use bwm-ng.Try opening two more terminals, one each to the client and server. In each, start bwm-ng.root@client:~# bwm-ng -u bits -t 1000 bwm-ng v0.6 (probing every 1.000s), press 'h' for help input: /proc/net/dev type: rate | iface Rx Tx Total ============================================================================== lo: 0.00 Kb/s 0.00 Kb/s 0.00 Kb/s eth0: 0.00 Kb/s 1017.34 Kb/s 1017.34 Kb/s eth1: 0.00 Kb/s 0.00 Kb/s 0.00 Kb/s ------------------------------------------------------------------------------ total: 0.00 Kb/s 1017.34 Kb/s 1017.34 Kb/sBy default, bwm-ng shows bytes/second. Press ‘u’ to cycle through bytes, bits, packets, and errors per second. Press ‘+’ or ‘-‘ to change the refresh time. I find that 1 or 2 seconds produces more accurate results on some hardware. Press ‘h’ for handy in-line help.Now, start the same iperf tests. Any packet losses will be immediately apparent, as the throughput measurements won’t match. The client will show 1 mbit in the Tx column, while the server will show a lower number in the Rx column.However, bwm-ng will not differentiate between traffic from iperf and other traffic at the same time. When that happens, it is still useful to use the packets/sec display to find the maximum packet throughput limits of your hardware.One warning to those who want to test TCP throughput with iperf: you cannot specify the data rate. Instead, iperf in TCP mode will scale up the data rate until it finds the maximum safe window size. For low-latency links, this is generally 85% of the true channel bandwidth as measured by UDP tests. However, as latency increases, TCP bandwidth decreases.

Hi All,I am struggling with iperf between windows and linux. When I install Linux on same hardware, I get ~1G bandwidth, however, when I install windows on it I get ~150 Mbps.I know distance does have a impact when it comes to throughput but why it doesn't have any effect when I install Linux on same hardware?Would like to know why iperf is sensitive about the distance on windows application but not on Linux?Stats:►Test 1:Version iperf 3.1.7Operating System: Linux Red Hat (3.10.0-1160.53.1.el7.x86_64)Latency between Server & client is 12ms$ ping 10.42.160.10 -c 2PING 10.42.160.10 (10.42.160.10) 56(84) bytes of data.64 bytes from 10.42.160.10: icmp_seq=1 ttl=57 time=12.5 ms64 bytes from 10.42.160.10: icmp_seq=2 ttl=57 time=11.9 ms--- 10.42.160.10 ping statistics ---2 packets transmitted, 2 received, 0% packet loss, time 1001msrtt min/avg/max/mdev = 11.924/12.227/12.531/0.323 ms►Upload from Client to Server$ iperf3 -c 10.42.160.10 -p 8443 -b 2G -t 5Connecting to host 10.42.160.10, port 8443[ 4] local 10.43.243.204 port 60094 connected to 10.42.160.10 port 8443[ ID] Interval Transfer Bandwidth Retr Cwnd[ 4] 0.00-1.00 sec 97.6 MBytes 819 Mbits/sec 0 2.60 MBytes[ 4] 1.00-2.00 sec 112 MBytes 942 Mbits/sec 0 2.61 MBytes[ 4] 2.00-3.00 sec 112 MBytes 941 Mbits/sec 0 2.61 MBytes[ 4] 3.00-4.00 sec 112 MBytes 942 Mbits/sec 0 2.64 MBytes[ 4] 4.00-5.00 sec 112 MBytes 942 Mbits/sec 0 2.66 MBytes[ ID] Interval Transfer Bandwidth Retr[ 4] 0.00-5.00 sec 546 MBytes 917 Mbits/sec 0 sender[ 4] 0.00-5.00 sec 546 MBytes 917 Mbits/sec receiveriperf Done.►Download from Server to Client$ iperf3 -c 10.42.160.10 -p 8443 -b 2G -t 5 -RConnecting to host 10.42.160.10, port 8443Reverse mode, remote host 10.42.160.10 is sending[ 4] local 10.43.243.204 port 60098 connected to 10.42.160.10 port 8443[ ID] Interval Transfer Bandwidth[ 4] 0.00-1.00 sec 108 MBytes 903 Mbits/sec[ 4] 1.00-2.00 sec 112 MBytes 942 Mbits/sec[ 4] 2.00-3.00 sec 112 MBytes 941 Mbits/sec[ 4] 3.00-4.00 sec 112

609 Mbits/sec[ 5] 9.00-10.00 sec 72.6 MBytes 609 Mbits/sec[ 5] 10.00-10.01 sec 1.05 MBytes 606 Mbits/sec- - - - - - - - - - - - - - - - - - - - - - - - -[ ID] Interval Transfer Bandwidth[ 5] 0.00-10.01 sec 0.00 Bytes 0.00 bits/sec sender[ 5] 0.00-10.01 sec 724 MBytes 607 Mbits/sec receiver In both cases, transfers from `192.168.X.220` to `192.168.X.201` are not running at full speeds, while they (nearly) are the other way around.What could be causing the transfer to be slower in one direction and not the other? Could this be a hardware issue? I'll mention that `192.168.X.220` is an "HP Slimline Desktop - 290-p0043w" with a Celeron G4900 CPU running Windows Server 2019 if that is somehow a bottleneck.I notice the same performance difference when transferring large files from the SSD on one system to the other.I'm hoping it's a software issue so it can be fixed, but I'm not sure. Any ideas on what could be the culprit? i386 Well-Known Member #2 QUOTE="jtabc, post: 347143, member: 44411"]Any ideas on what could be the culprit?[/QUOTE]Iperf is a Linux Tool, Not optimized for Windows. Some Versions shipped with a less optimized/Buggy cygwin.dll (there are no official binaries, all the Windows Files are from third Parties).Use iperf via Linux live Systems or try Other Software Like ntttcp (GitHub - microsoft/ntttcp) for Windows only Environments #3 QUOTE="jtabc, post: 347143, member: 44411"]Any ideas on what could be the culprit? Iperf is a Linux Tool, Not optimized for Windows.Some Versions shipped with a less optimized/Buggy cygwin.dll (there are no official binaries, all the Windows Files are from third Parties).Use iperf via Linux live Systems or try Other Software Like ntttcp (GitHub - microsoft/ntttcp) for Windows only Environments[/QUOTE]I'm not sure if it is an issue with

@prabhudoss jayakumar Thank you for reaching out to Microsoft Q&A. I understand that you want to know if there is a tool that can help with Bandwidth monitoring between VMs connected via Peering, is that right? You can always use the NTTTCP Tool for the same which is recommended by Azure. Please find details here for using this tool- You can also use Iperf for Bandwidth Monitoring. Please find details here- Download Iperf here- Please note: The network latency between virtual machines in peered virtual networks in the same region is the same as the latency within a single virtual network. The network throughput is based on the bandwidth that's allowed for the virtual machine, proportionate to its size. There isn't any additional restriction on bandwidth within the peering. The traffic between virtual machines in peered virtual networks is routed directly through the Microsoft backbone infrastructure, not through a gateway or over the public Internet. Therefore, factors such as the actual size of the VMs, regional latency between the VMs may affect the Bandwidth that you can achieve between the VMs. Hope this helps. Please let us know if you have any further questions and we will be glad to assist you further. Thank you! Remember: Please accept an answer if correct. Original posters help the community find answers faster by identifying the correct answer. Here is how. Want a reminder to come back and check responses? Here is how to subscribe to a notification.