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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13
votes
3answers
27k 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 ...
6
votes
4answers
16k 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 --...
5
votes
2answers
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 -> ...
4
votes
2answers
3k 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 ...
3
votes
1answer
16k 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 ...
3
votes
1answer
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 ...
3
votes
3answers
294 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 ...
2
votes
1answer
652 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-...
2
votes
1answer
218 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 ...
2
votes
1answer
415 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 ...
2
votes
1answer
6k 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 ...
2
votes
2answers
3k 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 ...
2
votes
1answer
179 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 ...
2
votes
1answer
852 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 ...
1
vote
1answer
80 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 ...
1
vote
1answer
717 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 ...
1
vote
2answers
108 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, ...
1
vote
1answer
207 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 ...
1
vote
1answer
772 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 ...
1
vote
2answers
2k 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 ...
1
vote
1answer
864 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 ...
1
vote
1answer
332 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 ...
1
vote
1answer
138 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 ...
1
vote
3answers
2k 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 ...
0
votes
6answers
16k 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.
0
votes
4answers
7k 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 ...
0
votes
1answer
4k 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 ...
0
votes
2answers
369 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@...
0
votes
1answer
313 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 ...
0
votes
1answer
39 views

iperf between two computers on different networks [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 exchanges or any other website ...
0
votes
1answer
147 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 ...
0
votes
1answer
788 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 ...
0
votes
1answer
1k 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 ...
0
votes
0answers
105 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 ...
0
votes
1answer
2k 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 <-&...