Questions tagged [iperf]

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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/...
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1answer
20 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 ...
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8 views

How can I simulate UDP fragementation for network testing?

Is there a way to use iperf3—or another similar tool—to generate fragmented UDP packets? I suspect my firewall isn't reassembling them properly.
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0answers
32 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-...
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21 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 ...
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0answers
99 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 ...
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14 views

Measuring speed of multiple OpenVPN servers

Use-case: I was provided with a bunch of OpenVPN configs that I can connect to, but the speed of the different servers vary to a great extent. And no way was provided to check the speed from provider. ...
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22 views

Swanctl rw scenario: Better iperf3 performance running [rw --> gw --> client] than [rw <— gw <— client]

I'm testing out some StrongSwan scenarios, (specifically this one) and I've discovered something interesting, when running iperf3 -c (client) from the roadwarrior Carol and iperf3 -s (server) from the ...
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0answers
25 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?
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1answer
224 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 ...
0
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1answer
297 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: (...
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1answer
146 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 ...
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2answers
735 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 ...
0
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1answer
95 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 ...
1
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1answer
5k 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
3
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1answer
713 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 ...
0
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1answer
241 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 ...
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2answers
12k 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 ...
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0answers
421 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 ...
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1answer
178 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 ...
2
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1answer
650 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....
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1answer
2k 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 ...
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1answer
1k 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 ...
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1answer
876 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 (...
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1answer
2k 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 ...
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2answers
2k 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 ...
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1answer
230 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 ...
1
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1answer
825 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-...
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0answers
536 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 ...
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1answer
327 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: ...
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2answers
574 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 ...
0
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1answer
79 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 ...
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0answers
1k 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 ...
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2answers
391 views

iperf bandwidth less than interface speed

I used linux bonding driver to bond 2 NICs in mode 6 in client PC. ethtool ethX shows speed =1000 ethtool bond0 shows speed =2000 but when i use iperf bandwidth of eth0 = 934Mbps bandwidth of eth1 ...
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1answer
5k views

How to increase bandwidth of bonding interface in mode 6?

I am new to Linux Bonding Driver. I have configured a bond in mode 6 which combines 2 ethernet interfaces. Their individual bandwidth is 937Mbps and 700 Mbps. But when both the interfaces are up, the ...
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2answers
921 views

What's the operation about iperf udp

I'm trying to doing some bandwidth test by run iperf on my device, My Network Max Bandwith is 100 Mbps (test by speed test CLI - https://github.com/sivel/speedtest-cli) And I ran the iperf UDP ...
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0answers
1k 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 ...
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1answer
415 views

LACP bond work intermittently on Cisco N5000

Our clients are using Centos 7.1 and 7.3. They are two 10GB card bonded to make a 20GB link. Each of the network card is connected to a pair of Cisco N5000 switch. While running cp or iperf, I can see ...
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0answers
145 views

What network setting could impact iperf3 results?

I am making some bandwidth tests to set a baseline for some other tests and I have a behaviour I cannot understand. The tests are done with iperf3 on Linux (with and without -R to get both up- and ...
2
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0answers
55 views

Measuring effectiveness of qdisc

I am trying to set the incoming and outgoing bandwidth of a particular interface. I set the outgoing bandwidth in the following way. sudo tc qdisc add dev f30e888e9a857_c handle 1: root htb default ...
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0answers
135 views

slow single connection between two otherwise fast machines

I'm having trouble with larger file transfers from one of our virtual servers to our office network. The virtual server acts as a VPN server, therefore we call it "VPN", but the usage of VPN is not of ...
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2answers
19k views

How to set the UDP Packet Size with iperf3?

How to set the UDP Packet Size with iperf3? The flag "-M" does not work with iperf3. Is there an alternative?
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3answers
5k views

IPERF 2.0.8/2.0.9 in Windows - "connect failed: Connection refused

I've been using iperf for some time but at present day i need to use the birectional test using -d or -r in the iperf command. The thing is that i always have "Connect failed: Connection refused" when ...
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1answer
4k views

Why the bandwidth is not ~10G?

I originally posted on "Network Engineering", but I was told to ask here. I have 2 servers connected with 10G cable between them directly. I need to know that the connection is good and it has indeed ...
2
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2answers
14k views

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 --...
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1answer
5k views

What's the default TCP window size of iperf3?

Does anyone know what's the default TCP window size for iperf3? It is not mentioned in the manual and I also can't find it in the output, when running a test.
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1answer
1k views

Iperf3 keeps hanging when running UDP test

I wrote a Python program that runs iperf3 in a for loop with different datagram sizes. I am using Python's subprocess.call function to run iperf3 like this: iperf3 -u -c 185.82.21.60 -b 100M -t 5 -l ...
4
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1answer
619 views

Segmentation fault when running nuttcp inside Docker

I am measuring the UDP throughput between two Docker containers that are connected by Docker's native overlay network. I already used iperf but also want to measure the throughput with nuttcp. But ...
7
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1answer
631 views

Right way of measuring overlay network performance

I am currently examining the performance (especially UDP throughput) of different Docker overlay networks. I do this by creating point-to-point connections between two hosts that are connected with a ...
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0answers
329 views

iperf actual send rate always lower than the expected target bandwidth until some equilibrium reached. Why?

I did an UDP iperf 2.0.5-Ubuntu test between two VMs on the same hypervisor. As can be seen in the iperf output below I started my first test with "-b 686M" flag. However, iperf reported that it was ...