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45 views

How slow can be a QCOW2 vm disk (proxmox/KVM) over NFS (dedicated 1Gbit)?

I'm running 3 proxmox 3.4 nodes using NFS shared storage with a dedicated 1GB network switch. root@lnxvt10:~# pveversion pve-manager/3.4-11/6502936f (running kernel: 2.6.32-43-pve) root@lnxvt10:~# ...
0
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0answers
25 views

Strange iperf3 behaviour with UDP streams

I am using iperf3 verson 3.0.11 to measure the throughput of a UDP stream between two virtual machines. The virtual machines are deployed via OpenStack. Of the physical hosts, one is located in ...
0
votes
2answers
164 views

No package iperf3 available CentOS

I'm trying to install iperf3 on a server to run some tests... Unfortunately I cannot. What do I need to do? Enable a repo or download a rpm file with wget? [root@localhost hodor]# yum install iperf3 ...
1
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0answers
12 views

Iperf Tcp Client and Server

I'd really like to know why the bandwith in the client is higher than the server, i can´t find the answer explaining why this happens. Thank you, Tiago Melancia Values of the bandwidth: Client ...
0
votes
1answer
48 views

Why is Apache2 serving as an iperf server?

My Question: Does anybody know why an apache2 server can act as an iperf server? I thought that an apache2 server does only answer HTTP requests. My Situation: I accidentally realized that an apache2 ...
1
vote
0answers
19 views

Network Traffic fluctuating, even with loopback

I am using iperf tool to benchmark my network interfaces on two identical machines (Dell Blade Server M620). Both have given different results. On 1st machine, I ran server and clients as: Server ...
1
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0answers
37 views

iperf shows 200Mb when host is the client, but 900Mb when it is the server

On host 'abc' I run: iperf -s -w 256k On host 'xyz' I run: iperf -c -w 256k And I get 900Mb. When I reverse the commands, making 'abc' the client, I get 200Mb. This means that abc's upload speed ...
0
votes
1answer
84 views

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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0answers
74 views

network throughput test: iperf vs netcat

I'm trying to measure the throughput of a 10 Gbit/s network. With iperf test I'm reaching about 9,3 gbits/s. However when I'm trying to copy some data with netcat, I'm getting just about 1,8 gbits/s. ...
0
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0answers
37 views

How to route multicast traffic under Ubutun 14.04

I am trying to achieve a very simple goal here, which is to set up a iperf server on my desktop machine to receive any incoming traffic, joe@longbeach:~$ iperf -s -u -B 224.0.0.1 -i 1 ...
0
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0answers
128 views

How to fix the amount of bandwidth of iperf in tcp mode?

I'm working on some experiments about my master's degree project. I'm studying some load-balancers (I'm not supposed to cite them here) and the aim is to get for each bandwidth the cpu % usage of a ...
1
vote
1answer
142 views

Network connection slow to server, only from one device

I have looked around, but there doesn't seem to be anyone with the same problem. I am getting almost no connection from my console (laptop) to one of my servers (Raspberry Pi 2 B) . All other ...
8
votes
2answers
3k views

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 ...
0
votes
1answer
64 views

Troubleshooting poor point to point (over internet) bandwidth between two machines

My problem started out as poor bandwidth between a 64 bit Win 7 Home OpenVPN server in location A (Northern Europe) and a Win 7 or Linux Client in location B (Southern Europe). Location A has FTTC ...
0
votes
1answer
73 views

Simulation of TX/RX Drop

I'm trying to get the "TX/RX Drop" values to increase. I've tried dropping packets using both iperf and iptables but the statistics aren't increasing even when packets are being dropped. Is there a ...
-2
votes
2answers
79 views

Is it possible to test throughput without server cooperation?

To measure throughput between two points in a network using iperf, you have to run iperf at one point in server mode. My question is, is there a tool I can use to measure this bandwidth without ...
0
votes
1answer
245 views

Teaming two NIC: iperf shows 200MB/s downloads but only 100MB/s upload

I have: One client with two 1000Mbps NICs, teamed using round-robin method One master with a 10Gbps NIC They are connected with a Huawei 10G switch (S5700). Then I ran iperf -s on master and ...
0
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0answers
2k views

my iperf connection test client side keeps showing connection refused

I am trying to setup an iperf test but the client side keeps getting connection refused message. Server side: ubuntu@webserver1:~$ iperf -s ...
1
vote
2answers
559 views

Slow local area network speeds

Updated on 2014-10-09 Disclaimer This question is similar to Unexplained slow gigabit network speeds but because the latter is still unanswered after 5 years, and that I think I'm able to add more ...
0
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0answers
51 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 ...
1
vote
0answers
383 views

Network Performance / SMB-CIFS / Guidance

I'm an IT professional working out of my home office. I'm having some performance problems (NAS file copies) which I'm trying to isolate, using iperf. My question is on iperf. Infrastructure - ...
2
votes
1answer
183 views

Poor network performance on Server 2008 machines

I have a network consisting of about 40 Windows 7 machines (physical) and 2 servers (Virtual, ESX) which are Server 2008 Std ed (one is a SBS 2008 but they're the same 'under the hood'). Network is a ...
2
votes
2answers
304 views

tcpreplay throughput on eth0 well below (iperf confirmed) max

I'm trying to replay captured UDP multicast packets at a rate of a couple of hundreds of Mbps, but it maxes out at about 86 Mbps. (For some strange reason, at other times during the day it ...
0
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0answers
336 views

Iperf UDP listening on used port

I get WARNING[9157] chan_sip.c: Retransmission timeout reached on transmission error on asterisk and trying to troubleshoot the problem. Now asterisk is listening on 5060 port: udp 0 0 ...
0
votes
1answer
421 views

iperf udp sequence number wireshark

I'm using iperf for generating udp traffic and my objective is to measure paquet loss. I wanted to know if the first 4 Bytes of Iperf Data are currently the sequence number.
0
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1answer
816 views

Difference in iperf output between client and server

Been playing with iperf for the last 4 hours and I'm unable to understand why the results are different in client and server. Consider the following iperf output on client : iperf -c 91.121.112.163 ...
0
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2answers
337 views

Debugging slow transfer rate from server [duplicate]

I'm trying to explain this as simple but documented as possible. This is not exclusive to this server or my current ISP. I've seen the same exact issue over the years while being with different ISPs ...
5
votes
1answer
10k views

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 ...
0
votes
0answers
646 views

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 ...
3
votes
1answer
342 views

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 ...
2
votes
2answers
423 views

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). ...
0
votes
2answers
133 views

Occasional Delay on Website Resources: Packet Loss Due to Bandwidth Cap?

My website loads more slowly than I think it should, due to a few of the assets taking an absurdly long time to download from the server. I've been trying to track down the cause of this. I'm about ...
4
votes
4answers
6k views

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 ...
3
votes
1answer
3k views

SSH tunnel speed is very slow

I have remote server with Ubuntu Linux and I want to establish SSH tunnel with this server from Windows machine using PuTTY(plink). I have to use this method for getting access to some service on this ...
1
vote
0answers
253 views

Iperf multiple streams

I need to test my network between two sites using iperf. I'd like to open parallel streams sending data on different (let's say 5 defined) ports, with random length from 10-1000, with random 1-2 ...
1
vote
3answers
7k views

Why is UDP slower than TCP on Ubuntu Server?

I transfer data between two Ubuntu Servers (12.04) via iperf on 1Gb LAN. iperf -s <-> iperf -c <addr> -n2G TCP speed = 925 Mbits/sec iperf -su <-> iperf ...
3
votes
1answer
2k views

How does iperf calculate throughput and jitter?

I've read that iperf basically tries to send as much information down a connection as quickly as possible reporting on the throughput achieved. This tool is especially useful in determining the volume ...
1
vote
1answer
2k views

Iperf bidirectional bandwidth measurement

Server side: # iperf -s ------------------------------------------------------------ Server listening on TCP port 5001 TCP window size: 85.3 KByte (default) ...
4
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3answers
3k views

Different versions of iperf for windows give totally different results

Measuring TCP output from a Windows client to Solaris server: WXP SP3 with iperf 1.7.0 --> returns an average around 90Mbit Same client, same server but iperf 2.0.5 for windows --> returns an average ...
2
votes
2answers
5k views

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 ...
2
votes
2answers
478 views

Interconnected switches Slow throughput

I am in charge of a network of which a portion of it looks like this: One DLink DGS-1210-24 (1) as the main switch. One DLink DGS-1210-16 (2) connected with cat5e 250 feet away connected on (1) One ...
6
votes
1answer
5k views

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 http://stackoverflow.com/questions/410616/increasing-the-maximum-number-of-tcp-ip-connections-in-linux and I ...
1
vote
1answer
2k views

Iperf udp test show only 50 % of bandwidth

I test bandwith with iperf. I set up UDP protocol. I'm trying to setup limit from 10 to 100 megabit/s. Until 90 megabit max speed is correct. When I write -b 100m or don't write this speed become ...
3
votes
1answer
3k views

iperf-like bidirectional bandwidth measurement through NAT

I am using iperf to measure my uplink speed between my home PC behind NAT and a fully accessible root server. It does so using a TCP connection. For whatever reason it seems that iperf can only ...
2
votes
2answers
130 views

File transfer - Bandwidth flickering for no reason

We are experiencing file transfer issues. I try to troubleshoot this problem but it is really hard. Here is a screenshot I took while transferring a file from my workstation to another server. The ...
7
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1answer
2k views

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 1000000000 ...
3
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1answer
2k views

IPerf - Reverse test

I'm trying to perform a test using IPerf but in a special case. Usually iperf client send data to iperf server, what I need in this case is the server send data back to the client in the same ...
2
votes
1answer
2k views

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 ...
1
vote
2answers
22k views

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?
3
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1answer
1k views

iperf 2.0.5 on Windows 7: degraded/inaccurate throughput

Was testing out some wireless equipment today using iperf on (at first) two Windows XP workstations. Throughput testing was fairly consistent at around 18Mbps. Moved equipment around (outside), ...