Questions tagged [iperf]
The iperf tag has no usage guidance.
128
questions
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How to measure network throughput with IPerf3 and multiple socat proxies
I have a particular device which acts as a "strange" TLS proxy and I want to measure the throughput of it with IPerf3.
The device under test is "Peter". It has an API to trigger ...
1
vote
1
answer
4k
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iperf test in reverse direction gives different result
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 ...
0
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1
answer
83
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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 ...
13
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4
answers
168k
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iperf connect failed: Connection refused
iperf -c 192.168.3.2 -i 2
connect failed: Connection refused
3.2 is another machine. I think the port might be blocked.
How can I make this work?
0
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0
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200
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File transfers very slow in one direction
I am having trouble debugging a connection issue :
Server A (OMV) has a fast internet connection : 900mbps down / 600 mbps up
Client B (Windows 10 using wsl) has a decent internet connection : ...
0
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1
answer
145
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Why does iperf3 or TCP stack merge TCP packets?
Using this simple command:
iperf3 -c localhost --time 1 -l 100 --bitrate 100M
Then watching the output with:
sudo tcpdump -i lo -B 10000000 tcp port 5201
I would expect to see lots of 100 byte ...
8
votes
2
answers
59k
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How to start iperf3 server in UDP mode?
I would like to test UDP connectivity with iperf3 but do not know how to start it in UDP server mode.
iperf3 -s only opens a TCP socket:
root@srv ~# lsof -i -P | grep iperf3
iperf3 21030 ...
3
votes
4
answers
20k
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using Iperf3 to test upload and download
How to use Ipfer3 to test upload and download speed or in other words which data of the output given below represents upload and download speed ?
Iperf3 output
4
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3
answers
25k
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iperf3 error - unable to create a new stream: permission denied
I am new to using iperf but others in my company use it but today it is acting strangely.
From the server:
iperf3 -s
which results in cmd showing:
Server listening on 5201.
From the client:
iperf3 --...
1
vote
1
answer
657
views
iperf3: Multiple user Streams test does not start
Im trying to use iperf3 to test where issues lie at a client that uses RDP to connect to our terminal-server. Their issue is that the RDP window freezes (mouse clicks mostly still go trough). ...
0
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0
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68
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MPLS Implementation OpenFlow Iperf Testing
I have a mininet topology that consists of two hosts and two ovs switches. h1-eth0 is connected to s1-eth1 and h2-eth0 is connected to s2-eth2 and s1-eth2 and s2-eth1 is also connected. h1 is for ...
1
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0
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406
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iPerf3 --reverse different results (2.5GB link)
I recently purchased 2.5GB adapters for my main Desktop (Windows 10) and NAS server (Ubuntu 20.04).
When testing with iPerf3 FROM Windows, I only get 1GB. But when I use the --reverse flag, I get the ...
0
votes
1
answer
94
views
KVM guest low network speed
I have a KVM guest VM running RHEL 8.7 (12vCPU, 24GB RAM) and a hypervisor with 10Gb NICs.
I'm getting weird results when using iperf3 on my guest machine as a client and a TrueNAS server as a server. ...
0
votes
1
answer
2k
views
iperf3 test bandwidth : TCP much slower than UDP
I'm trying to find out why one of my servers, used for fileserving, is sending files at a very slow rate, around 7 Mbits/sec, through nginx.
I've been using iperf3 to test transfer rate between ...
2
votes
1
answer
859
views
iperf3 errors and retransmissions on ESXi
When running iperf3 to test a 100G connection between a VMware ESXi box and a TrueNAS Core box, I'm seeing the following on the ESXi box:
The message "iperf3: getsockopt - Function not ...
5
votes
4
answers
26k
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Testing download speed using iperf
I am using iperf to test my bandwidth. But I am not getting whether it is showing my upload or download speed. Say, I have two PCs A and B. If I want to test how fast I can download a file to A from B,...
0
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1
answer
2k
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Getting an iperf "connect failed: connection refused" error on ubuntu when running multiple threads
I have 3 computers hooked up to a local network. I have written a python script to open a dedicated iperf server and an iperf client on separate threads. I want every computer to connect to the other ...
1
vote
1
answer
375
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Why is iperf3 data transfer slower than scp?
I have been measuring the throughput between two hosts connected via a fiber channel. The OS is CentOS 7.9.2009 and iperf3 version is 3.1.7 (RPM). One of the tests was the measurement of transfer ...
0
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1
answer
918
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How can I use an iperf output and only grep average Bandwidth?
I am here finding a way to display the average of iperf bandwidth using the script. I am not sure whats wrong with command, i dont get the output of Bandwidth displayed. I need output something like ...
2
votes
3
answers
3k
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Why am I only achieving 2.5Gbps over a 10Gbe direct connection between 2 machines?
I have 2 machines directly connected to each other with a 7 foot Cat6a ethernet cable (included in the box of the NIC cards). The PCIe x4 NIC I bought and in both machines is this: https://www.amazon....
0
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0
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479
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how to test 10G NIC in loopback for full throughput?
I am using 10G NIC x520-DA2 (which is x8 Lane) in windows 10 Enterprise 64 Bit on DELL Optiplex 7080 Tower with Intel Core i7-10700 . X520-DA is installed on PCie slot 2 of optiplex 7080 that is PCIe ...
1
vote
0
answers
572
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Windows Server 2019 high round-trip time low transfer bandwidth
I have two Windows Servers 2019 with a round-trip time of 88 ms between them. When I try to measure bandwidth with iperf3 I get only around 16 Mbits/sec in both directions with a single stream. To get ...
10
votes
3
answers
42k
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Iperf from one interface to another on the same computer?
I need to test network throughput of a server to/from itself (it's a lonnnng story!).
I love Iperf and use it across the network, but, I just can't figure out how to bind it to a single interface and ...
12
votes
2
answers
39k
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Extreme UDP packet loss at 300Mbit (14%), but TCP > 800Mbit w/o retransmits
I have a linux box I use as the iperf3 client, testing 2 identically equipped Windows 2012 R2 server boxes with Broadcom BCM5721, 1Gb adapters (2 ports, but only 1 used for the test). All machines are ...
7
votes
2
answers
2k
views
Why multicast UDP can be slower than unicast UDP?
I have two machines (with Centos 7.3 on both) connected via 1G switch.
When I measure UDP thoughput between macines with iperf it gives about 850 Mbit/s.
However when I measure multicast UDP thoughput ...
0
votes
1
answer
2k
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Benchmarking AWS outbound Internet bandwidth (egress) "up to 25 Gbps"
We conducted our tests on c6gn.2xlarge AWS instances located is us-east-1 region, which are advertised in AWS documentation to have a network performance of "Up to 25 Gbps" with a baseline ...
5
votes
1
answer
3k
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socat tun device very low throughput
I was tinkering around with socat and tried to use socat for creating a TUN device for tunneling between two debian stretch servers. However, throughput seemed very low and comparing with iperf ...
3
votes
1
answer
410
views
AMD EPYC 7413 slow down to arround 400mhz when running iperf
we are trying to setup a 40gbit connection between two servers and get weird cpu behaviour when using iperf. It is also only using around 10Gbit/s of the possible 40.
Server specs:
AMD EPYC 7413
8x ...
0
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1
answer
32
views
Does Throughput calculated adds up using multiple (all active) physical adaptor
I had a network adaptor of speed 20Gbps. By stressing this adaptor using one of benchmarking tools (netperf is the tool which I used), I was able to get ~18Gbps which is well accepted.
Now, after ...
0
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0
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356
views
transfer file at iperf bandwidth/throughput
I need to transfer a file between 2 servers, the output of iperf is:
TCP window size: 85.0 KByte (default)
------------------------------------------------------------
[ 3] local X.X.X.X port 58986 ...
1
vote
0
answers
133
views
iperf3 showing packetloss between 2 directly connected servers
I have 2 Dell PowerEdge-R620 servers with following configuration
Processor: 2 X Intel(R) Xeon(R) CPU E5-2637 v2 @ 3.50GHz
RAM: 64GB
Storage: 10 SAS drives (10K RPM) with RAID 10.
NIC: QUAD Ports 2 X ...
1
vote
0
answers
36
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Asymmetry in Linux VM transfer rate
I have two Linux VMs, let's call them VM1 and VM2.
I have on VM1 an 80 Gb file.
When I try to transfer this file from VM1 to VM2 the transfer rate is almost 256 Mb/s.
scp 80Gblargefile VM2:/home/...
0
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1
answer
300
views
iperf3 not consistent across different OS'es
I have connected two rooms via a 10Gbit fiber connection. The connection has one MikroTik switch with four SFP+ on one end (room A) and an Ubiquiti Unifi 24 ports with two SFP+ (room B).
On Room A, I ...
0
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0
answers
1k
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append date and time before each line in a text log file in windows 10
I want to append date and time before each line in a text log file in windows
I run iperf command in cmd in windows 10.
iperf.exe -c192.168.5.199 -u -t4 -i1 -f Kbytes -w1024k -b1024k >> client-...
1
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0
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143
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iPerf3 - normal and reverse measurement in the same instance
I can start a normal measurement (with 192.168.1.2 being the server) with
iperf3 -c 192.168.1.2
and a reverse measurement with
iperf3 -c 192.168.1.2 -R
Is there any way I can do both a normal and a ...
0
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0
answers
233
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Getting 2g speeds on hyper-v VM through a 10g nic
I'm testing my speeds using IPERF as I've recently installed a 10G cisco switch and intel 10g NIC's on some servers to communicate with a nas server.
I noticed my reads and write were awful so I've ...
1
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0
answers
76
views
iptables tool to measure latency instead of bandwidth
I'm trying to measure the latency of having a lot of iptables rules.
I tried to use iperf but I think that bandwidth is not what i want.
Any help with this?
1
vote
1
answer
1k
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Why is there a difference in speed of forward and reverse traffic over 10 G network in iperf tool
I have a 10G network setup between my two servers (say, Server1 and Server2) and I'm using iperf tool to measure the bandwidth of the network.
Here are test cases that I performed,
Test Case 1: (...
1
vote
1
answer
398
views
FreeNAS + LAGG Slow Transfer?
I built a new file server that should be way overbuilt for its purpose. It has 2 Intel(R) Xeon(R) CPU E5-2660 v3, with 128GB of ram and it is running LCAP through an Intel X540T2 network card to a ...
1
vote
0
answers
7k
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Can't get multicast to work (iperf)
I have some problems to get SLP (service location protocol; I play around with the OpenSLP implementation) to work. It uses multicast on 239.255.255.253, port 427. To narrow down the problem I decided ...
0
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1
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643
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variable number of lost UDP packets reported by iperf, linux scheduling?
I am testing a connectivity with an iperf server (iperf version 2.0.13 (21 Jan 2019) pthreads) running on a Bananpi M2+ single-board computer (Debian, 5.1.1-BPI-Kernel #1 SM). For different target ...
1
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2
answers
4k
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Why udp has lower throughput than tcp? [duplicate]
I am measuring the tcp and udp throughput by iperf3. I run iperf3 in virtual machines, one as server and the other as client. The VMs are connecting via 10 Gbps link. The results show that tcp get ...
0
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1
answer
849
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Using trickle/trickled to limit bandwidth throughput of iperf3
I'm doing some throughput testing on some radio units that have narrow channel bandwidth settings (for example sub 250KHz bandwidth). During my testing of iperf3, I noticed that the slowest speed it ...
2
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2
answers
9k
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Measuring network performance between Windows and Linux
I'm using iperf to estimate network performance between Windows and Linux.
For TCP iperf shows 312 Mbits/sec from a Linux server to a Windows client, but it shows only 160 Mbits/sec from a Windows ...
3
votes
1
answer
4k
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using random ports with iperf/iperf3 [closed]
I am using Iperf/iperf3 -c remotehost which is
iPerf3 is a tool for active measurements of the maximum achievable bandwidth on IP networks. It supports tuning of various parameters related to ...
0
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1
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699
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At Iperf3, TCP weird behavior
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 ...
1
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2
answers
5k
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Is iperf valid to measure network performance?
We are investigating performance issues in one of our software deployment between our application servers (Windows) and our Redis instances (Linux).
On a 10 Gbits/s link single TCP connections can ...
0
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1
answer
527
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Issues with Cisco IPSec VPN speed. Fast uploads, slow downloads from external to internal servers
We are using a Cisco ASA5516, configured with a IPsec (IKEv1) split tunnel VPN.
When uploading files to a server behind the firewall, the transfer speeds are normal (up to 10mbps).
When downloading ...
1
vote
4
answers
24k
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WARNING: did not receive ack of last datagram after 10 tries
I use iperf to test bandwidth, if i set large test bandwidth, it gives me "WARNING: did not receive ack of last datagram after 10 tries" and there is no report, i want to know what does this mean?
...
0
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1
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2k
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Low bandwidth when Iperfing data thorugh IPSEC tunnel
We have two server connected next to each other. When we're iperfing each other through 'simple' physical interaces - we're getting ~5GB/S of bandwidth. But when im sending traffic through tunneled (...