Skip to main content

Questions tagged [iperf]

The tag has no usage guidance.

Filter by
Sorted by
Tagged with
0 votes
1 answer
32 views

Slow throughput when iptables is running (10GbE)

When iptables is running the throughput on the 10GbE gets slowed down and I have no idea why. Gentoo Linux with Kernel 6.6.21 CPU: Intel Xeon E5-1650v4 ~#@❯ iperf3 -c 192.168.0.12 Connecting to host ...
Daniel Mann's user avatar
0 votes
1 answer
75 views

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 ...
lnksz's user avatar
  • 101
0 votes
1 answer
137 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
  • 1
0 votes
0 answers
223 views

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 : ...
Elerir's user avatar
  • 1
0 votes
1 answer
186 views

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 ...
Ken Y-N's user avatar
  • 115
1 vote
1 answer
821 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). ...
asdfmoin's user avatar
1 vote
0 answers
460 views

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 ...
EngageBasic's user avatar
0 votes
1 answer
103 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. ...
chetzz's user avatar
  • 1
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 ...
Baptiste Placé's user avatar
0 votes
1 answer
2k views

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 ...
Tyler Durden's user avatar
2 votes
1 answer
915 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 ...
lunadesign's user avatar
0 votes
1 answer
1k views

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 ...
ls440's user avatar
  • 1
0 votes
0 answers
513 views

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 ...
optiplex91's user avatar
1 vote
0 answers
584 views

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 ...
hwfanatic's user avatar
1 vote
1 answer
399 views

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 ...
pdp's user avatar
  • 778
0 votes
1 answer
2k views

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 ...
Eric's user avatar
  • 101
3 votes
1 answer
430 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 ...
Flaep's user avatar
  • 81
0 votes
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 ...
Chandan Hegde's user avatar
0 votes
0 answers
387 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 ...
nbari's user avatar
  • 568
1 vote
0 answers
139 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 ...
skb007's user avatar
  • 146
1 vote
0 answers
37 views

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/...
Salvatore D'angelo's user avatar
0 votes
1 answer
314 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 ...
francisaugusto's user avatar
0 votes
0 answers
1k views

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-...
Jyoti Kumar's user avatar
1 vote
0 answers
153 views

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 ...
Kaiser's user avatar
  • 11
0 votes
0 answers
241 views

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 ...
UserSN's user avatar
  • 159
1 vote
0 answers
83 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?
PRVS's user avatar
  • 135
1 vote
1 answer
401 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 ...
laxer's user avatar
  • 121
1 vote
1 answer
1k views

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: (...
Rohit Lal's user avatar
  • 111
0 votes
1 answer
651 views

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 ...
BigK's user avatar
  • 33
1 vote
2 answers
5k views

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 ...
sarah sh's user avatar
  • 111
0 votes
1 answer
925 views

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 ...
Aaron Hesse's user avatar
3 votes
4 answers
21k views

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
USER's user avatar
  • 63
3 votes
1 answer
4k views

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 ...
USER's user avatar
  • 63
0 votes
1 answer
706 views

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 ...
nimdrak's user avatar
  • 139
8 votes
2 answers
61k views

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 ...
WoJ's user avatar
  • 3,657
5 votes
1 answer
3k views

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 ...
1gd_1bs37coua9dd's user avatar
0 votes
1 answer
542 views

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 ...
ChrisKnowles's user avatar
2 votes
3 answers
3k views

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....
Mike's user avatar
  • 121
2 votes
1 answer
3k views

How can iperf reporting packet loss in udp

Iperf is the well known tool to calculate throughput. When i tried udp throughput using iperf on my linuxpc, It reported that 10% of packet loss. In UDP protocol, data gram did not receice any ...
Vijay Kalyanam's user avatar
0 votes
1 answer
3k views

iperf3 UDP not reliable with iptables drop random

I'm performing some local test on my network with iperf3 using UDP connections between 2 Ubuntu 18.04 hosts. But it seems that the UDP iperf3 connections it is not robust to support a random packet ...
user886869's user avatar
0 votes
1 answer
2k views

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 (...
Edvinas's user avatar
  • 63
1 vote
1 answer
4k views

How can I use an iperf output and only grep 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 ...
Gutsygibbon's user avatar
0 votes
2 answers
3k views

Undefined iperf3 ports?

I am trying to identify all of the ports affiliated with an iperf3 UDP session and am noticing that the TCP handshaking uses an undefined(?) port on the iperf3 server. Is there a way to specify all ...
Nate's user avatar
  • 557
0 votes
1 answer
482 views

Iperf2 capture received promiscous mode traffic Not Multicast

I want to capture all traffic in my Iperf server that I listen for promiscously, even if I am not the intended IP. I know you can do this with Multicast addresses, but I do not want to follow that ...
Daniël Schoonwinkel's user avatar
1 vote
1 answer
1k views

The FastNetMon client why not show the Incoming and Outgoing traffic?

I use VMWare created two VMs on my Windows Server. two VM all are CentOS-7.2. My FastNetMon version is bellow: /opt/fastnetmon/fastnetmon --version Version: 1.1.3 master git-...
aircraft's user avatar
  • 396
1 vote
0 answers
851 views

I test the Iperf failed

In my Server(CentOS7.2, address is 103.193.202.2), I run the iperf server: # iperf -u -s ------------------------------------------------------------ Server listening on UDP port 5001 Receiving 1470 ...
aircraft's user avatar
  • 396
0 votes
1 answer
462 views

ieprf vs iperf3 metrics does not match

I am not a network expert but I was measuring the network between to physical hosts using iperf and I got different results depending of the version I was using. Server configuration: CPU: ...
masber's user avatar
  • 205
1 vote
2 answers
942 views

How to measure bandwidth per cpu utilization [closed]

I'm trying to measure efficiency of the networking system and looking for a tool that either allows to limit max bandwidth for each test or, ideally, limit cpu utilization. At the end I need to have ...
Kentzo's user avatar
  • 131
1 vote
1 answer
192 views

Can ARP expire mid iperf connection?

If one runs an iperf connection between a node 'A' and a node 'B' is it possible that the arp entry expires from one of the nodes. [I have a simple mininet topology and while running an iperf ...
George J. Adams's user avatar
1 vote
0 answers
2k views

Low network speed with small packets

Using iperf3 to test the network with --length 1000 --no-delay: iperf3 --interval 1 --time 3 --no-delay --length 1000 --parallel 100 --client 10.0.0.3 Result: [SUM] 0.00-3.00 sec 835 MBytes ...
benji's user avatar
  • 487