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Questions tagged [iperf]

120 questions
12
votes
2 answers

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 connected via a single 1Gb switch. Testing UDP…
Evgeniy Berezovsky
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11
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5 answers

Iperf CSV output format

If I use iperf with -y C and -r arguments to test bidirectional transfer and export it as a CSV. I get some output but the problem is that I don't know what the column names are. For example it shows three rows of data but I don't know which…
user350325
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11
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3 answers

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?
Hao
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11
votes
4 answers

Packet loss rate with iperf and tcpdump

I tested a line for its link quality with iperf. The measured speed (UDP port 9005) was 96Mbps, which is fine, because both servers are connected with 100Mbps to the internet. On the other hand the datagram loss rate was shown to be 3.3-3.7%, which…
stefita
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8
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3 answers

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 only listen via that. From the documentation, I…
William Hilsum
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7
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2 answers

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 it results in something like 95 Mbit/s (almost…
Alexei Osipov
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7
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1 answer

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 Docker overlay network and then run iperf inside…
arne.z
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7
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3 answers

Pre-compiled Iperf 2.x binary for win32?

I'd like to do some network testing on Windows using Iperf. The latest on sourceforge appears to be 2.0.4. However, it's only available as source to be compiled. I attempted to do some google searching for a pre-compiled version, but all I could…
Ryan Bolger
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7
votes
1 answer

Increasing the number of outbound TCP connections

I am developing a small test client for websockets. I am using Ubuntu 11.04 . I have read https://stackoverflow.com/questions/410616/increasing-the-maximum-number-of-tcp-ip-connections-in-linux and I have done the following sudo sysctl -w …
Harihara Vinayakaram
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6
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2 answers

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 root 3u IPv4 15606995 0t0 TCP *:5201…
WoJ
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6
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1 answer

iperf max udp multicast performance peaking at 10Mbit/s?

I'm trying to test UDP multicast throughput via iperf but it seems like it's not sending more than 10Mbit/s from my dev machine: C:\> iperf -c 224.0.166.111 -u -T 1 -t 100 -i 1 -b…
TJF
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5
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1 answer

ESXi 5.5, slow network speed when writing to guests

This is an issue that has been bugging me for a lot time with ESXi. I had the issue with my old Dell server (ESXi 5.0 and 5.5) and even with my new Dell T20 (ESXi 5.5). For the current issue at hand I will only focus on the new Dell T20 server, to…
Jueki
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5
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1 answer

Bandwidth Throttling using tc qdiscs

I am trying to limit the bandwidth between a simple iperf server and client, using a third, passive machine acting as a bridge. With no interference, iperf returns a bandwidth of ~90 Mbits/sec. My goal is to create a root qdisc that sends all…
Ian
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4
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1 answer

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 when I am starting the server instance and then…
arne.z
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4
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2 answers

Is it reasonably safe to host a publicly accessible iperf3 server?

CentOS 6.x An IT team member would like run iperf3 on a publicly accessible server for the purpose of running on-demand connectivity checks from anywhere (no restrictions on remote source IP). Does this present any major security concerns? The…
Mike B
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