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Questions tagged [iperf]

For questions about the open-source software Iperf, where it is a widely used tool for network performance measurement and tuning. Remember that only questions in relation to on topic network devices are allowed.

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iperf3: why do client and server agree on data amount equal but differ on bandwidth?

I want to test a device for its throughput. Therefore, I am using iperf3. After sending data for 10 seconds, my server reports receiving the same amount of data but at a lower speed than the client. ...
Jakob's user avatar
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0 votes
1 answer
60 views

iperf3 download and upload test simultaniously giving abnormal results

I have a server (Lenovo using Ubuntu) and 2 clients (both Mac). The server is connected with a Wi-Fi router over Eth interface. The two clients are connected with Wi-Fi router over WLAN interface. All ...
SAM's user avatar
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1 vote
1 answer
104 views

Iperf testing- Slow transfer speeds [closed]

I'm doing Iperf testing at my company's branch office circuit and I'm getting results that are causing me concern. I'm testing from a laptop through an access switch>distro switch> Fortigate> ...
Network Engineer Sussman's user avatar
1 vote
1 answer
199 views

Mellanox (NVIDIA) SN3700 switch: Cumulus Linux configuration to force traffic path?

I want to stress all ports on a SN3700 switch with iPerf. I want to force the traffic to go through each port, so port 1 to port 2, port 2 to port 3, port 3 to port 4, etc. The switch is running ...
CrystalBryan's user avatar
0 votes
1 answer
261 views

IPerf test| Server side Sender data shows that the bandwidth is zero but Client has bandwidth of 125 Mbps

I conducted Iperf3 test on my network. I received in server side that sender transfer bandwidth is zero but Client side showed a bandwidth of 125 Mbps. What went wrong? The command I wrote was Iperf3 -...
Finny Joseph's user avatar
0 votes
1 answer
404 views

Inconsistent behavior of link aggregation

I'm testing bandwidth between two switches and I noticed link aggregation behaves inconsistently between test runs. I'm testing with a single instance of iperf with 2 streams. Sometimes the load is ...
Elliott B's user avatar
  • 101
1 vote
1 answer
2k views

Is it possible to conduct a bandwidth test using iperf between two computers located on different network? [closed]

Is it possible to check bandwidth using iperf between two computers on different networks (i.e., geographically apart)? I researched a lot, and every answer on Stack Exchange or any other website ...
user avatar
1 vote
2 answers
884 views

Bandwidth, Latency, Download speed and Upload speed

In the midst of trying to diagnose a slow vpn issue, I'm getting a bit confused by the various metrics being mentioned by the many different techs I've been speaking with. From what I understand, ...
Silfheed's user avatar
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0 votes
1 answer
1k views

how to send a number of TCP packets and capture only those packets using tshark?

I'm using iperf3 to send 1005 TCP packets with the commands: iperf3 -s -i 1 -f m -p 5200 -D iperf3 -c 10.60.0.113 -k 1005 -bitrate 0 --reverse --omit 2 -p 5200 In server, client respectively. The ...
Natiya's user avatar
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0 answers
327 views

pinging with iperf vs without iperf

I am running a basic point to point topology on mininet. If I do h2 ping h1, I get such rtt values: rtt min/avg/max/mdev = 0.028/0.067/0.129/0.022 ms But when I ping while the iperf is measuring, my ...
a125's user avatar
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2 answers
2k views

Iperf results on Bandwidth and Transfer do not make sense

I'm having trouble understanding why iperf is behaving the way it is. I'm just trying to send UDP traffic from a Raspberry Pi to my Computer. This is what it looks like on the Client Side: pi@...
moodieftw's user avatar
1 vote
1 answer
2k views

IPerf3 UDP does not meet specified bitrate [closed]

We are currently performing tests over a wireless network and are having some issues trying to get the correct configuration of iperf3. Our server side command line is as follows iperf3 -s -p 5101 ...
Lhh92's user avatar
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0 votes
1 answer
2k views

iperf without TCP server

I'm running packets through an FPGA that doesn't support TCP. I'd like to test the performance of the link with a tool such as iperf. Since iperf uses TCP to communicate metadata it's a bit of a show ...
philn's user avatar
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0 votes
1 answer
4k views

TCP cwnd is increasing when congestion occur

I am a newbie network engineer. I did a small experiment with iperf3. But I run into a small problem. (1) My question. I think TCP flow do not act properly despite of its congestion control. The flow ...
nimdrak's user avatar
  • 125
1 vote
1 answer
127 views

Why I cannot see packet loss on GRE over capacity tunnels?

I have the following topology set on AWS where there are 4 CSR 1000v Routers deployed and Segment Routing enabled in which the Segment Routing Headend is R1 and the destination is R3. I aim to send ...
Khalil Mebarkia's user avatar
1 vote
1 answer
359 views

Understanding Throughput of interfaces problem on Cisco Routers

I have the following topology set on AWS where there are 4 CSR 1000v Routers deployed and Segment Routing enabled in which the Segment Routing Headend is R1 and the destination is R3. I aim to send ...
Khalil Mebarkia's user avatar
2 votes
1 answer
1k views

Collect UDP packets lost during iPerf test

I'm testing my network infrastructure where I'm using iPerf and UDP protocol. I'm using the following: On the server side: ubuntu@ip-172-0-1-11:~$ iperf -s -u and the client side: ubuntu@ip-172-2-...
Khalil Mebarkia's user avatar
1 vote
2 answers
4k views

Why is there a difference on the amount of data transferred during a UDP iperf measurement?

I have the following result from a UDP throughput test as measured by iperf3 $ iperf3 -u -t 10 -c 192.168.1.2 -b 100M -V iperf 3.6+ Linux pi-raspberry1 4.4.38-v7+ #938 SMP Thu Dec 15 15:22:21 GMT ...
ealiaj's user avatar
  • 113
2 votes
1 answer
341 views

IPoIB with Netem (Latency emulation) Poor performance

I have to emulate a wide area network. My setup contains two servers with MT27500 Family [ConnectX-3] Infiniband cards. Default latency between both nodes is ~0.4ms and iperf test shows throughput of ...
Khayam Gondal's user avatar
2 votes
1 answer
241 views

Definition of bandwidth capacity for an internet connection

First, I want to test the data rate of a fibre-optic internet connection, but I understand that results are affected by the circumstances of the test, like number of hops between the CPE and the other ...
Mikkel Rev's user avatar
2 votes
1 answer
545 views

cisco catalyst 3560 rate-limit on vlan is not observable with iperf

I have a dumbbell topology with two hosts and two switches. Host1 is connected to Switch1, Switch1 is connected to Switch2, and Switch2 is connected to Host2. To make things more interesting Host1 ...
Matt Hall's user avatar
  • 145
2 votes
1 answer
2k views

How can I find bottlenecks using IPERF3?

I've just started using IPERF and I'm rather confused about the results I'm getting. When IPERF reports bandwidth does it actually mean throughput as when repeating tests the values returned seem to ...
Gaarsin's user avatar
  • 21
5 votes
1 answer
31k views

iperf: send specific volume?

I wanted to test some different test cases. I wanted to transmit 1MB, 10MB, 100MB, ..., 1GB, ... and measure bandwith with iperf. In the manual stands that I can use a combination of -l and -n ...
user674907's user avatar
1 vote
1 answer
1k views

Calculating the Jain Fairness Index of two connections - what values to use?

I'm using GNS3 and I have 3 VMs. I established two simultaneous TCP connections to an iperf server I created on VM2. VM-1 -- VM-2 VM-3 -- VM-2 Using the iperf -c <IP of VM2> command, I ...
Lars's user avatar
  • 13
2 votes
1 answer
11k views

Iperf results on UDP Bandwidth

I am currently testing iperf with a view to automating some testing servers for our company. To do this I am using an iperf server in the cloud which is well connected and is only 5 hops away from ...
Paula Livingstone's user avatar
1 vote
1 answer
163 views

Why I don't see drops with a TCP flows in Linux

I wanted to observe the congestion window of a TCP flow so for that I have to nodes (using Linux namespaces) connected to each other through veth pairs and a bridge. To limit bandwidth to 10mbps I ...
edgarstack's user avatar
5 votes
2 answers
2k views

WiFi TCP iperf throughput: upstream vs down stream

In a WLAN iperf3 TCP throughput test, I have the following results: With exactly the same setting, operation in 802.11ac (3x3) (DFS channel) (TCP Cubic) 30 nodes as server receiving iperf -> ...
HenryGiraldo's user avatar
0 votes
1 answer
3k views

Use iperf to split multiple tcp streams between 2 NIC on same client (similar to IxChariot)

I have 2 PCs connected to each other using two 1 Gbps ethernet link, to have an aggregate data bandwidth of 2 Gbps. In IxChariot, I can create multiple TCP pairs and split them into: PC1_LAN1 <-&...
eecs's user avatar
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4 votes
2 answers
6k views

IPERF TCP vs UDP

I had to determine UDP performance over multi-hop network , I used MAC Air over gigabit ethernet ( Thunderbolt). As is customary, TCP was tested and the gig over link was saturated ~900mbps, but ...
Bharat C Penumutchu's user avatar
1 vote
1 answer
1k views

How to verify that the connection is 10G? [closed]

I have 2 servers connected with 10G cable between them directly. I need to know that the connection is good and it has indeed 10G throughput. I used IPERF to verify the bandwidth. According to the ...
theateist's user avatar
  • 111
1 vote
3 answers
3k views

What iperf flags should I use to test link LACP bond total speed

I have created an channel group with LACP, I know that single TCP session will be sent over a single line. My hashing algorithm is set to source mac address. So how can I be sure that the bandwidths ...
Edik Mkoyan's user avatar
0 votes
4 answers
8k views

Lower throughput with fixed TCP window size?

I used iperf3 to measure the effect that the TCP window has on throughput. I am measuring the throughput between two virtual machines which are located on different physical hosts. So I wrote a Python ...
arne.z's user avatar
  • 101
2 votes
2 answers
4k views

Where are UDP packets lost during iPerf test?

I'm testing a 802.11 wireless link using iPerf and the UDP protocol. Using the -b command at the client, I can set the bandwidth to an arbitrary number (e.g. 1 Gbps) that's much higher than the link ...
Lorenz Forvang's user avatar
0 votes
1 answer
7k views

GNS3: performance tests using iperf3? [duplicate]

I'm running some performance tests on GNS3 (I know I shouldn't, but it is not until Friday that I will have the college lab available), and I'm trying to compare real BW or "speed" and ...
Daniel's user avatar
  • 15
4 votes
3 answers
699 views

There's huge gap between two results for iperf

I used iperf -c FOO_NODE -t 120 -i 10 to test the network with the other node FOO_NODE, sometimes I get the result like: [ ID] Interval Transfer Bandwidth [ 3] 0.0-10.0 sec 3.75 MBytes ...
Tony Han's user avatar
  • 143
0 votes
6 answers
20k views

VOIP testing with IPERF tool

Does iperf support VOIP? If yes! then please tell me what are the commands for testing voip and video streaming.
sak's user avatar
  • 69
6 votes
4 answers
22k views

Iperf 'set bandwidth' command issues

I am unable to set the bandwidth on both sides using the Iperf tool. When I use the command iperf -c 192.168.1.15 -b 10m -l 32k -w 128k I get this error: --iperf: ignoring extra argument -- 10m --...
sak's user avatar
  • 69
0 votes
1 answer
423 views

Tuning UDP-lite protocol instead of UDP with "IPERF" tool

How do i test network connection for UDP-Lite protocol (along with checksum coverage) instead of UDP with "IPerf" tool. for udp we use following command-> iperf -s -u -i 1 what command should i ...
sak's user avatar
  • 69
3 votes
1 answer
4k views

standard results for gigabit ethernet iperf

I can't achieve good transfer rate through scp and I wonder if the network configuration isn't tuned up correctly. I've noticed some differences when running iperf through tcp vs udp. Are these ...
dnul's user avatar
  • 133
1 vote
1 answer
861 views

Why don't I see client-to-server TCP traffic when sniffing iPerf TCP throughput?

When I do an Omnipeek capture of an iPerf TCP throughput test over WiFi, I only see TCP Acks from the iPerf server to the client. How come I don't see any TCP frames from the client to the server? I ...
elin05's user avatar
  • 517
13 votes
3 answers
37k views

Wifi TCP iperf throughput: 1 stream vs multiple streams?

In a WLAN iperf TCP throughput test, multiple parallel streams will give me higher throughput than 1 stream. I tried increasing the TCP window size, but I still cannot achieve the max throughput with ...
elin05's user avatar
  • 517