Questions tagged [iperf]

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iperf: avg latency is larger than max latency?

I use iperf to measure the latency between two machines. The configuration is very simple and uses UDP. Server: iperf -s -u -p 50000 -e -i 1 Client: iperf -c 12.34.56.78 -u -p 50000 -e -i 1 -b 1M The ...
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13 views

How to interpret `--bidir` bidirectional option of iperf3

When I run an iperf3 test between two devices on the same network, I get data for both transmit and receive on the client's results. What more, if anything, does the bidirectional flag --bidir offer? ...
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124 views

Windows iperf3 speed test slower than Linux

Hardware setup NAS: Core i3 7100, Intel X540T2 10GbE Switch: Mikrotik CRS305 PC: Ryzen 7 2700, Intel X540T2 10GbE Cables: 2x Cat 7 cables Software Setup NAS: Ubuntu 20.04 alexwang@alex-nas2 ~ (...
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164 views

Slow download WAN -> pfSense -> PC

i have observed a strange effect in my home network. While i get full gigabit speed between all the components in the LAN and full speed to/from the WAN at the router and the NAS, the PC only reaches ...
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36 views

IPerf3 on Windows Slower than Linux?

Got an interesting one. I've got three computers on the same switch in my office. I have been making some infrastructure changes recently and decided to run some iperf3 runs on my PC down to my ...
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48 views

Throughput oscillating in speedtest with iPerf3

I have to test my network speed using iPerf3. [SETUP] I'm using a Virtual Machine running Ubuntu 18.04 connected to a smartphone through WiFi. I'm using HE.NET on my smartphone, which allows me to ...
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243 views

Running iperf or iperf3 over proxy

Is it possible to run iperf or iperf3 over a proxy. I'm behind a local proxy (Jana) and would like to test this network performance.
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41 views

What is the bottleneck of loopback?

Recently I am curious about that question, so I installed iperf3 on my macOS to benchmark my the performance of the loopback on my macOS. However, the CPU usages didn't reach 100%, which is expected ...
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115 views

Understanding iperf3 results

want to know, does the bitrate stats in iperf3 for UDP only consider payload data sent per unit time or payload data + length of headers sent per unit time? Sample Stats: -----------------------------...
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1answer
93 views

How to configure a standalone performance test for HBA/CNA interface cards using iperf

I’m looking for a solution to run a performance test to an HBA and CNA interface cards on a stand-alone server running Linux OS (e.g Centos7), without having to connect it to another server/switch. I ...
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497 views

Iperf for Windows - where to find newer versions?

I have just noticed that in openSuse I have iperf version 3.5, where as on Windows I cannot find anything newer then 3.1.3, which dates from June 2016! I still assume that iperf is the most ...
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1answer
257 views

iperf indicating 940 Mbits/sec using cat 5 cable

I have a box of old ethernet cables and was going to use iperf to determine if they were cat 5 or cat 5e. As a sanity check I found one that still had labels on it indicating it was cat 5 but when I ...
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1answer
149 views

Mismatch in results of iperf and iptraf

I ran TCP throughput from client(iperf -c IP -i1 -p19223) to server(iperf -s -i1 -p19223). The stats showed me bandwidth of ~5Gbps. However, when I ran iptraf on the server, it reported that the ...
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447 views

TCP traffic not working through Iperf tool in ubuntu

I am using system-A(interace name:tun0; IP: 192.168.3.1) and system-B(interface n ame:ss200; 192.168.3.2) which run on ubuntu. When I try sending traffic in TCP mode from A to B or vice versa, by ...
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1answer
157 views

iperf: connecting to remote server consistently faster than local network

So I turned my old laptop into a home server. Both the server (old laptop) and my main machine are connected to the same router wirelessly. Both are running Ubuntu 18.04. Everything seemed to work ...
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2answers
3k views

How can I output iperf results for only Interval and Bandwidth?

I am trying to get the output from the command iperf -c 10.0.0.1 -t 3600 -i 2 And only need the Interval and bandwidth fields listed for the entire hour of logging. I haven't used grep or awk in ...
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1answer
5k views

Understand iperf3 results

I'm trying to diagnose network performance in my house. I ran iperf3 on two Macs wired to a gigabit Ethernet switch (through cable runs in wall). My results were: Connecting to host 10.0.1.192, ...
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1answer
3k views

iperf3 error exactly 7 seconds into running the test

I am running an iperf test to measure bandwidth from a host iperf client to a container iperf server.Exactly 7 seconds into the test iperf gives an error & abruptly ends the test. The message ...
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1answer
1k views

USB 3.0 Ethernet adapter outperforms motherboard PCIe GBE

I recently did three different Iperf bandwidth tests using various network adapters. My question is: How does a USB 3.0 ethernet adapter outperform a built in gigabit ethernet controller on the ...
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1answer
702 views

What means 's' and 'u' letters on CPU utilization in iperf3 command with -V?

i have very simple question: When Im using Iperf3 with my server and on client i add paramater -V which mean it will display more detailed information it's display information about CPU utilization on ...
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398 views

iperf3 limiting bandwidth fails

I want to use iperf3 to test some QoS settings of a router. Therefore I want to simulate a lone-lasting but low bandwidth connection.* I tried the following: $ iperf3 -c MYSERVER -b 100K Connecting ...
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1answer
1k views

TCP throughput much better than UDP

I'm monitoring the performances of a WAN link with iperf between two windows machines on both ends. Surprisingly (for me), TCP single session default window reaches a throughput of 12Mbps, while UDP ...
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3answers
12k views

ping works but iperf3 doesn't show any traffic for TCP

machine A has IP (eth0: 192.168.1.1, eth1: 10.10.xxx.yy) machine B has IP (eth0: 192.168.1.2) A and B are connected through RJ5 on eth0, both sides. ping works fine on both side, but when running ...
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1answer
3k views

Why does a Bidirectional iperf request freezes on the server to client side?

To diagnose the difference in network trafic between two locations and our main server center, I'm using iperf to log the traffic rate with the following command: iperf -c <server ip> -F ...
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1answer
510 views

Why does `iperf` report huge values for bandwidth?

When I try to run iperf on local server it reports reasonable values iperf -c 127.0.0.1 -p 631 ------------------------------------------------------------ Client connecting to 127.0.0.1, TCP port ...
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1k views

Speed over VPN is 10x slower than connection to VPN or VPN<=>Destination

I'm trying to setup VPN for my own use. I have noticed very strange issue with speeds which I struggle to understand. Question: What is causing slow download speed from AWSFrankfurt when using VPN? ...
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896 views

not getting fast 802.11ac WiFi speeds

I'm using a Linksys WRT AC1900 router and an Intel 7260 client adapter on my desktop. I've never seen speeds > 10MiB/s at my previous apartment, probably because the router was 30 feet away and the ...
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2answers
10k views

iperf giving incorrect results

I've just had new broadband installed, and wanted to test its throughput using iperf3. However it appears to be giving considerably different results than more conventional speed tests. E:\tmp> ...
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1answer
1k views

iperf and Wireshark show different data rate

I was testing the capture performance of a sniffer application in Linux. I have a Windows machine that sends UDP multicast packets to the capture port of the sniffer system using iperf at 8Mbits/s. I ...
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0answers
1k views

Why is iPerf UDP bandwidth so much lower that iPerf TCP?

I need to perform a single direction iPerf test. Bi-directionally, using TCP, I get 25Mbps. But single direction using UDP I only get 0.7Mbps. Why is UDP rate so much lower that TCP? iPerf client ...
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1answer
2k views

Graphical representation of iperf3 results

I'm using Iperf3 on 2 machines and actually I'm running 2 instances of Iperf3, one to generate traffic with high priority and the other generates traffic with low priority. I would like to generate a ...
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734 views

Can I have server and client on the same machine and run network bandwidth test using iperf?

I have two ethernet ports (eth0 and eth1) on my system. I've tested the bandwidth with two systems and got ~940Mbit/s. If I use one of the ports as server and the other as client, I always go through ...
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1answer
8k views

iperf returning “bind failed: cannot assign requested address” in Windows XP and 7

I am trying to set up iperf on an old HP server running Windows XP Professional to test multicast, but whenever I issue the command iperf -s -u -B <ip address>, it returns: bind failed: ...
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2answers
342 views

Iperf network benchmark measures under-utilized?

I am working on two embeddded high performance network routers and I have connected them point-to-point via a 10Gbit optical fibre cable. I ran iperf benchmarks on them and when I connect through an ...
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1answer
463 views

Slow LAN connection (especially receiving) on Windows 8

I was diagnosing my SMB performance issues when I noticed my whole network speed was off. These are my benchmarking results between my desktop and my Linux server: Both are connected using CAT6 and ...
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4k views

Iperf tests in reverse direction

I used iperf to measure the max throughput for TCP connection between two ubuntu machines. Both the machines were directly connected be means of a 1Gbps cable. When I performed iperf tests i obtained ...
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1answer
5k views

How to run IPERF on DD-WRT?

I have IPERF for Windows installed on a desktop computer. Now I want to connect this computer to the router and conduct a simple throughput performance test. For that I will need IPERF running on the ...
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2answers
11k views

How to perform a network loopback test using TTCP or IPERF?

The PC has two Gigabit Ethernet ports. They function as two separate network adapters. I'm trying to do a simple loopback test between the two. I've tried TTCP and IPERF. They're giving me hard time ...