Anyone who gave a try to the new Fedora 13 Beta.
Few new features which I appreciate:
1. NetworkManager Command Line
2.Enhanced NFS Client IPv6
3.System Rollback With Btrfs
4.Zarafa - Zarafa Outlook Sharing is a Microsoft Exchange replacement
Tuesday, April 20, 2010
Sunday, April 18, 2010
Installing Mac Fonts on Ubuntu 10.04
Installing the fonts:
1. From the Linux terminal, download Mac fonts with this command:
$ wget http://ubuntu-debs.googlecode.com/files/macfonts.tar.gz
2. Untar or extract the downloaded file:
$ tar zxvf macfonts.tar.gz
3. Move macfonts folder to the /fonts directory:
$ sudo mv macfonts /usr/share/fonts/
4. Reload the font cache:
$ sudo fc-cache -f -v
Using the fonts:
You can now test or use the fonts by going to System --> Preferences --> Appearance, and then clicking on the "Fonts" tab. Here is a sample setup on using theMac fonts:
Application font: Lucida MAC 10
Document font: Lucida MAC 10
Desktop font: Lucida MAC 10
Window title font: LucidaMacBold 10
Fixed width font: Lucida Console 10
1. From the Linux terminal, download Mac fonts with this command:
$ wget http://ubuntu-debs.googlecode.com/files/macfonts.tar.gz
2. Untar or extract the downloaded file:
$ tar zxvf macfonts.tar.gz
3. Move macfonts folder to the /fonts directory:
$ sudo mv macfonts /usr/share/fonts/
4. Reload the font cache:
$ sudo fc-cache -f -v
Using the fonts:
You can now test or use the fonts by going to System --> Preferences --> Appearance, and then clicking on the "Fonts" tab. Here is a sample setup on using theMac fonts:
Application font: Lucida MAC 10
Document font: Lucida MAC 10
Desktop font: Lucida MAC 10
Window title font: LucidaMacBold 10
Fixed width font: Lucida Console 10
Minimum RAM for Fedora 13 beta?
As a rule of thumb, I wouldn't go one byte less than 512MB for 32-bit, or 1GB for 64-bit.
More realistically, 1GB is a probably a good "minimum RAM" to start with for any GUI OS (32- or 64-bit), then increase as-needed. People might disagree, but it's honestly my experience that if you really need to have less than 1GB RAM ... then you probably shouldn't be considering a Gnome or KDE desktop. If you don't have enough RAM, you should probably consider a server (e.g. text-mode) environment, or a distro like Puppy Linux (which supports REALLY tiny memory footprints!), or Ubuntu Remix.
More realistically, 1GB is a probably a good "minimum RAM" to start with for any GUI OS (32- or 64-bit), then increase as-needed. People might disagree, but it's honestly my experience that if you really need to have less than 1GB RAM ... then you probably shouldn't be considering a Gnome or KDE desktop. If you don't have enough RAM, you should probably consider a server (e.g. text-mode) environment, or a distro like Puppy Linux (which supports REALLY tiny memory footprints!), or Ubuntu Remix.
Wednesday, March 31, 2010
How to test Multicast Packet Filtering?
Today morning I started my day testing with Multicast Packet Filtering. I had Ubuntu 9.10 and CentOS 5.4 in my VM running over ESX 4.1.I decided to make CentOS as Client and Ubuntu as server for the setup.
First of all, I downloaded iperf as yum was not feeling well today(just kidding).
Its simple to install,download the package and install. Luckily, I dint get any dependency hell.
On Ubuntu Box:
SERVER MACHINE
=====================================
sudo iperf -s -u -B 224.0.65.68 -i 1
--------------------------------------
server listening on UDP port 5001
Binding to local address 224.0.65.68
Joining multicast group 224.0.65.68
UDP Buffer size: 120 Kbytes(default)
------------------------------------------
[ 3] local 224.0.65.688 port 5001 connected with 10.112.173.86 port 38577
[ 3] 0.0.-1.0 sec 128 KBytes 1.05 Mbits/sec 0.228 ms 0/ 89 (0%)
...
...
On CenTOS Box(Client):
iperf -c 224.0.65.68 -u -T 5 -t 5
----------------------------------
Client connecting to 224.0.65.68, UDP port 5001
sending 1470 byte datagrams
setting multicast TTL to 5
UDP buffer size: 126 KBytes(default)
------------------------------------------
[ 3] local 10.112.173.86 port 38577 connected with 224.0.65.68 port 5001
[ 3] 0.0- 5.0 sec 642 Kbytes 1.05 Mbits/sec
[ 3] Sent 447 datagrams
1.It clearly shows that multicast address is 224.0.65.68.
e.g. server> iperf -s -u -B -i 1
This will have the iperf servers listening for datagram (-u) from the address (-B multicast address), with a periodic interval of 1s (-i 1)
2. Configure the client VM, connecting to the multicast group address and setting the TTL (-T, --ttl) as needed
e.g. client> iperf -c -u -T 5 -t 5
This will have the client connected to the multicast address (-c multicast address), with a TTL of 5 (-T 5), sending data for 5 seconds
NOTE: Use tcpdump or ethereal on server VMs to capture and analyze IP packets and ensure its validity.
Run the test for 120 sec.
That's it..
You Have just finally tested Multicast packet Filtering.
Have a Cool Rainy Weather in Bangalore.
First of all, I downloaded iperf as yum was not feeling well today(just kidding).
Its simple to install,download the package and install. Luckily, I dint get any dependency hell.
On Ubuntu Box:
SERVER MACHINE
=====================================
sudo iperf -s -u -B 224.0.65.68 -i 1
--------------------------------------
server listening on UDP port 5001
Binding to local address 224.0.65.68
Joining multicast group 224.0.65.68
UDP Buffer size: 120 Kbytes(default)
------------------------------------------
[ 3] local 224.0.65.688 port 5001 connected with 10.112.173.86 port 38577
[ 3] 0.0.-1.0 sec 128 KBytes 1.05 Mbits/sec 0.228 ms 0/ 89 (0%)
...
...
On CenTOS Box(Client):
iperf -c 224.0.65.68 -u -T 5 -t 5
----------------------------------
Client connecting to 224.0.65.68, UDP port 5001
sending 1470 byte datagrams
setting multicast TTL to 5
UDP buffer size: 126 KBytes(default)
------------------------------------------
[ 3] local 10.112.173.86 port 38577 connected with 224.0.65.68 port 5001
[ 3] 0.0- 5.0 sec 642 Kbytes 1.05 Mbits/sec
[ 3] Sent 447 datagrams
1.It clearly shows that multicast address is 224.0.65.68.
e.g. server> iperf -s -u -B
This will have the iperf servers listening for datagram (-u) from the address (-B multicast address), with a periodic interval of 1s (-i 1)
2. Configure the client VM, connecting to the multicast group address and setting the TTL (-T, --ttl) as needed
e.g. client> iperf -c
This will have the client connected to the multicast address (-c multicast address), with a TTL of 5 (-T 5), sending data for 5 seconds
NOTE: Use tcpdump or ethereal on server VMs to capture and analyze IP packets and ensure its validity.
Run the test for 120 sec.
That's it..
You Have just finally tested Multicast packet Filtering.
Have a Cool Rainy Weather in Bangalore.
Tuesday, March 30, 2010
Quick Command Reference: List Loaded Drivers on Linux?
driverquery is the command on Windows to get list of drivers. In the same way, on Linux we have lsmod which lists the drivers installed on the box.
lsmod is a program to show the status of modules in the Linux Kernel. lsmod is a trivial program which nicely formats the contents of the /proc/modules, showing what kernel modules are currently loaded.
Example: lsmod of a typical ESX 4.1 Box could show:
[root@esx]# lsmod
Module Size Used by
nfs 245688 2
lockd 68016 2 nfs
nfs_acl 3904 1 nfs
edd 10696 0
ppdev 10056 0
parport_pc 28584 0
i2c_dev 10696 0
i2c_core 23128 1 i2c_dev
sunrpc 162248 11 nfs,lockd,nfs_acl
ipt_REJECT 6080 0
xt_tcpudp 3520 0
ipt_LOG 6656 0
x_tables 17096 3 ipt_REJECT,xt_tcpudp,ipt_LOG
parport 41100 2 ppdev,parport_pc
nvram 8456 0
sg 36520 0
vmxnet_console 23360 1
vmnixmod 789052 56 vmxnet_console
lsmod is a program to show the status of modules in the Linux Kernel. lsmod is a trivial program which nicely formats the contents of the /proc/modules, showing what kernel modules are currently loaded.
Example: lsmod of a typical ESX 4.1 Box could show:
[root@esx]# lsmod
Module Size Used by
nfs 245688 2
lockd 68016 2 nfs
nfs_acl 3904 1 nfs
edd 10696 0
ppdev 10056 0
parport_pc 28584 0
i2c_dev 10696 0
i2c_core 23128 1 i2c_dev
sunrpc 162248 11 nfs,lockd,nfs_acl
ipt_REJECT 6080 0
xt_tcpudp 3520 0
ipt_LOG 6656 0
x_tables 17096 3 ipt_REJECT,xt_tcpudp,ipt_LOG
parport 41100 2 ppdev,parport_pc
nvram 8456 0
sg 36520 0
vmxnet_console 23360 1
vmnixmod 789052 56 vmxnet_console
Sunday, March 28, 2010
Understanding Jumbo Frames !!
Whether or not Gigabit Ethernet (and beyond) should support frame sizes (i.e. packets) larger than 1500 bytes has been a topic of great debate. With the explosive growth of Gigabit ethernet, the impact of this decision is critically important and will affect Internet performance for years to come.
Most of the debate about jumbo frames has focused on local area network performance and the impact that frame size has on host processing requirements, interface cards, memory, etc. But what is less well known, and of critical concern for high performance computing, is the impact that frame size has on wide area network performance. This document discusses why you should care, and about the largely ignored but important impact that frame size has on the wide area performance of TCP.
How jumbo is a jumbo frame anyway?
Ethernet has used 1500 byte frame sizes since it was created (around 1980). To maintain backward compatibility, 100 Mbps ethernet used the same size, and today "standard" gigabit ethernet is also using 1500 byte frames. This is so a packet to/from any combination of 10/100/1000 Mbps ethernet devices can be handled without any layer two fragmentation or reassembly.
"Jumbo frames" extends ethernet to 9000 bytes. Why 9000? First because ethernet uses a 32 bit CRC that loses its effectiveness above about 12000 bytes. And secondly, 9000 was large enough to carry an 8 KB application datagram (e.g. NFS) plus packet header overhead. Is 9000 bytes enough? It's a lot better than 1500, but for pure performance reasons there is little reason to stop there. At 64 KB we reach the limit of an IPv4 datagram, while IPv6 allows for packets up to 4 GB in size. For ethernet however, the 32 bit CRC limit is hard to change, so don't expect to see ethernet frame sizes above 9000 bytes anytime soon.
How can jumbo frames and 1500 byte frames coexist?
Two basic approaches exist:
* On a port by port basis, where everything "downstream" from a given port is known to support jumbo frames.
* Using 802.1q Virtual LANs, where jumbo frame and non-jumbo frame devices are segregated to different VLANs.
Jumbo frames bad for multimedia?
For applications that are sensitive to burst drops, delay jitter, etc., it can be argued that large frames are a bad idea. No application has to use large frames however, so the question is really whether other application's large frames will negatively impact your application's small ones. This is primarily an issue of slot time, i.e. how much will a large packet delay (or quantize) the time(s) available to transmit the small packets.
A 9000 byte GigE packet takes the same amount of time to transmit as a 900 byte fast ethernet packet or a 90 byte 10 Mbps ethernet packet. So jumbo frames on gigabit ethernet at worse add less delay variation than 1500 byte frames do on slower ethernets. And no one is suggesting that slower ethernets use 9000 byte frames. As for queueing delay concerns, that could happen whether packets are large or small. If delivery QoS is required, then the routers need to implement some kind of priority or expedited forwarding, regardless of the packet sizes. Tiny frames (including 53 byte ATM cells) may be helpful when multiplexing lower bit rate streams, but they become increasingly ridiculous on gigabit and beyond links.
Most of the debate about jumbo frames has focused on local area network performance and the impact that frame size has on host processing requirements, interface cards, memory, etc. But what is less well known, and of critical concern for high performance computing, is the impact that frame size has on wide area network performance. This document discusses why you should care, and about the largely ignored but important impact that frame size has on the wide area performance of TCP.
How jumbo is a jumbo frame anyway?
Ethernet has used 1500 byte frame sizes since it was created (around 1980). To maintain backward compatibility, 100 Mbps ethernet used the same size, and today "standard" gigabit ethernet is also using 1500 byte frames. This is so a packet to/from any combination of 10/100/1000 Mbps ethernet devices can be handled without any layer two fragmentation or reassembly.
"Jumbo frames" extends ethernet to 9000 bytes. Why 9000? First because ethernet uses a 32 bit CRC that loses its effectiveness above about 12000 bytes. And secondly, 9000 was large enough to carry an 8 KB application datagram (e.g. NFS) plus packet header overhead. Is 9000 bytes enough? It's a lot better than 1500, but for pure performance reasons there is little reason to stop there. At 64 KB we reach the limit of an IPv4 datagram, while IPv6 allows for packets up to 4 GB in size. For ethernet however, the 32 bit CRC limit is hard to change, so don't expect to see ethernet frame sizes above 9000 bytes anytime soon.
How can jumbo frames and 1500 byte frames coexist?
Two basic approaches exist:
* On a port by port basis, where everything "downstream" from a given port is known to support jumbo frames.
* Using 802.1q Virtual LANs, where jumbo frame and non-jumbo frame devices are segregated to different VLANs.
Jumbo frames bad for multimedia?
For applications that are sensitive to burst drops, delay jitter, etc., it can be argued that large frames are a bad idea. No application has to use large frames however, so the question is really whether other application's large frames will negatively impact your application's small ones. This is primarily an issue of slot time, i.e. how much will a large packet delay (or quantize) the time(s) available to transmit the small packets.
A 9000 byte GigE packet takes the same amount of time to transmit as a 900 byte fast ethernet packet or a 90 byte 10 Mbps ethernet packet. So jumbo frames on gigabit ethernet at worse add less delay variation than 1500 byte frames do on slower ethernets. And no one is suggesting that slower ethernets use 9000 byte frames. As for queueing delay concerns, that could happen whether packets are large or small. If delivery QoS is required, then the routers need to implement some kind of priority or expedited forwarding, regardless of the packet sizes. Tiny frames (including 53 byte ATM cells) may be helpful when multiplexing lower bit rate streams, but they become increasingly ridiculous on gigabit and beyond links.
Understanding iperf?
Iperf is a tool to measure the bandwidth and the quality of a network link. Jperf can be associated with Iperf to provide a graphical frontend written in Java.
The network link is delimited by two hosts running Iperf.
The quality of a link can be tested as follows:
- Latency (response time or RTT): can be measured with the ping command.
- Jitter (latency variation): can be measured with an Iperf UDP test.
- Datagram loss: can be measured with an Iperf UDP test.
The bandwidth is measured through TCP tests.
To be clear, the difference between TCP (Transmission Control Protocol) and UDP (User Datagram Protocol) is that TCP use processes to check that the packets are correctly sent to the receiver whereas with UDP the packets are sent without any checks but with the advantage of being quicker than TCP.
Iperf uses the different capacities of TCP and UDP to provide statistics about network links.
Finally, Iperf can be installed very easily on any UNIX/Linux or Microsoft Windows system. One host must be set as client, the other one as server.
Here is a diagram where Iperf is installed on a Linux and Microsoft Windows machine.
Linux is used as the Iperf client and Windows as the Iperf server. Of course, it is also possible to use two Linux boxes.
screenshot Iperf bandwidth measure client server
Iperf tests:
no arg.
-b
-r
-d
-w
Default settings
Data format
Bi-directional bandwidth
Simultaneous bi-directional bandwidth
TCP Window size
-p, -t, -i
-u, -b
-m
-M
-P
-h Port, timing and interval
UDP tests, bandwidth settings
Maximum Segment Size display
Maximum Segment Size settings
Parallel tests
help
Jperf:
no arg.
-d
-u, -b Default settings
Simultaneous bi-directional bandwidth
UDP tests, bandwidth settings
Default Iperf settings:
Also check "Jperf section.
By default, the Iperf client connects to the Iperf server on the TCP port 5001 and the bandwidth displayed by Iperf is the bandwidth from the client to the server.
If you want to use UDP tests, use the -u argument.
The -d and -r Iperf client arguments measure the bi-directional bandwidths. (See further on this tutorial)
Client side:
#iperf -c 10.1.1.1
------------------------------------------------------------
Client connecting to 10.1.1.1, TCP port 5001
TCP window size: 16384 Byte (default)
------------------------------------------------------------
[ 3] local 10.6.2.5 port 33453 connected with 10.1.1.1 port 5001
[ 3] 0.0-10.2 sec 1.26 MBytes 1.05 Mbits/sec
Server side:
#iperf -s
------------------------------------------------------------
Server listening on TCP port 5001
TCP window size: 8.00 KByte (default)
------------------------------------------------------------
[852] local 10.1.1.1 port 5001 connected with 10.6.2.5 port 33453
[ ID] Interval Transfer Bandwidth
[852] 0.0-10.6 sec 1.26 MBytes 1.03 Mbits/sec
Data formatting: (-f argument)
The -f argument can display the results in the desired format: bits(b), bytes(B), kilobits(k), kilobytes(K), megabits(m), megabytes(M), gigabits(g) or gigabytes(G).
Generally the bandwidth measures are displayed in bits (or Kilobits, etc ...) and an amount of data is displayed in bytes (or Kilobytes, etc ...).
As a reminder, 1 byte is equal to 8 bits and, in the computer science world, 1 kilo is equal to 1024 (2^10).
For example: 100'000'000 bytes is not equal to 100 Mbytes but to 100'000'000/1024/1024 = 95.37 Mbytes.
Client side:
#iperf -c 10.1.1.1 -f b
------------------------------------------------------------
Client connecting to 10.1.1.1, TCP port 5001
TCP window size: 16384 Byte (default)
------------------------------------------------------------
[ 3] local 10.6.2.5 port 54953 connected with 10.1.1.1 port 5001
[ 3] 0.0-10.2 sec 1359872 Bytes 1064272 bits/sec
Server side:
#iperf -s
------------------------------------------------------------
Server listening on TCP port 5001
TCP window size: 8.00 KByte (default)
------------------------------------------------------------
[852] local 10.1.1.1 port 5001 connected with 10.6.2.5 port 33453
[ ID] Interval Transfer Bandwidth
[852] 0.0-10.6 sec 920 KBytes 711 Kbits/sec
Top of the page
Bi-directional bandwidth measurement: (-r argument)
The Iperf server connects back to the client allowing the bi-directional bandwidth measurement. By default, only the bandwidth from the client to the server is measured.
If you want to measure the bi-directional bandwidth simultaneously, use the -d keyword. (See next test.)
Client side:
#iperf -c 10.1.1.1 -r
------------------------------------------------------------
Server listening on TCP port 5001
TCP window size: 85.3 KByte (default)
------------------------------------------------------------
------------------------------------------------------------
Client connecting to 10.1.1.1, TCP port 5001
TCP window size: 16.0 KByte (default)
------------------------------------------------------------
[ 5] local 10.6.2.5 port 35726 connected with 10.1.1.1 port 5001
[ 5] 0.0-10.0 sec 1.12 MBytes 936 Kbits/sec
[ 4] local 10.6.2.5 port 5001 connected with 10.1.1.1 port 1640
[ 4] 0.0-10.1 sec 74.2 MBytes 61.7 Mbits/sec
Server side:
#iperf -s
------------------------------------------------------------
Server listening on TCP port 5001
TCP window size: 8.00 KByte (default)
------------------------------------------------------------
[852] local 10.1.1.1 port 5001 connected with 10.6.2.5 port 54355
[ ID] Interval Transfer Bandwidth
[852] 0.0-10.1 sec 1.15 MBytes 956 Kbits/sec
------------------------------------------------------------
Client connecting to 10.6.2.5, TCP port 5001
TCP window size: 8.00 KByte (default)
------------------------------------------------------------
[824] local 10.1.1.1 port 1646 connected with 10.6.2.5 port 5001
[ ID] Interval Transfer Bandwidth
[824] 0.0-10.0 sec 73.3 MBytes 61.4 Mbits/sec
Top of the page
Simultaneous bi-directional bandwidth measurement: (-d argument)
Also check the "Jperf" section.
To measure the bi-directional bandwidths simultaneousely, use the -d argument. If you want to test the bandwidths sequentially, use the -r argument (see previous test).
By default (ie: without the -r or -d arguments), only the bandwidth from the client to the server is measured.
Client side:
#iperf -c 10.1.1.1 -d
------------------------------------------------------------
Server listening on TCP port 5001
TCP window size: 85.3 KByte (default)
------------------------------------------------------------
------------------------------------------------------------
Client connecting to 10.1.1.1, TCP port 5001
TCP window size: 16.0 KByte (default)
------------------------------------------------------------
[ 5] local 10.6.2.5 port 60270 connected with 10.1.1.1 port 5001
[ 4] local 10.6.2.5 port 5001 connected with 10.1.1.1 port 2643
[ 4] 0.0-10.0 sec 76.3 MBytes 63.9 Mbits/sec
[ 5] 0.0-10.1 sec 1.55 MBytes 1.29 Mbits/sec
Server side:
#iperf -s
------------------------------------------------------------
Server listening on TCP port 5001
TCP window size: 8.00 KByte (default)
------------------------------------------------------------
[852] local 10.1.1.1 port 5001 connected with 10.6.2.5 port 60270
------------------------------------------------------------
Client connecting to 10.6.2.5, TCP port 5001
TCP window size: 8.00 KByte (default)
------------------------------------------------------------
[800] local 10.1.1.1 port 2643 connected with 10.6.2.5 port 5001
[ ID] Interval Transfer Bandwidth
[800] 0.0-10.0 sec 76.3 MBytes 63.9 Mbits/sec
[852] 0.0-10.1 sec 1.55 MBytes 1.29 Mbits/sec
Top of the page
TCP Window size: (-w argument)
The TCP window size is the amount of data that can be buffered during a connection without a validation from the receiver.
It can be between 2 and 65,535 bytes.
On Linux systems, when specifying a TCP buffer size with the -w argument, the kernel allocates double as much as indicated.
Client side:
#iperf -c 10.1.1.1 -w 2000
WARNING: TCP window size set to 2000 bytes. A small window size
will give poor performance. See the Iperf documentation.
------------------------------------------------------------
Client connecting to 10.1.1.1, TCP port 5001
TCP window size: 3.91 KByte (WARNING: requested 1.95 KByte)
------------------------------------------------------------
[ 3] local 10.6.2.5 port 51400 connected with 10.1.1.1 port 5001
[ 3] 0.0-10.1 sec 704 KBytes 572 Kbits/sec
Server side:
#iperf -s -w 4000
------------------------------------------------------------
Server listening on TCP port 5001
TCP window size: 3.91 KByte
------------------------------------------------------------
[852] local 10.1.1.1 port 5001 connected with 10.6.2.5 port 51400
[ ID] Interval Transfer Bandwidth
[852] 0.0-10.1 sec 704 KBytes 570 Kbits/sec
Top of the page
Communication port (-p), timing (-t) and interval (-i):
The Iperf server communication port can be changed with the -p argument. It must be configured on the client and the server with the same value, default is TCP port 5001.
The -t argument specifies the test duration time in seconds, default is 10 secs.
The -i argument indicates the interval in seconds between periodic bandwidth reports.
Client side:
#iperf -c 10.1.1.1 -p 12000 -t 20 -i 2
------------------------------------------------------------
Client connecting to 10.1.1.1, TCP port 12000
TCP window size: 16.0 KByte (default)
------------------------------------------------------------
[ 3] local 10.6.2.5 port 58316 connected with 10.1.1.1 port 12000
[ 3] 0.0- 2.0 sec 224 KBytes 918 Kbits/sec
[ 3] 2.0- 4.0 sec 368 KBytes 1.51 Mbits/sec
[ 3] 4.0- 6.0 sec 704 KBytes 2.88 Mbits/sec
[ 3] 6.0- 8.0 sec 280 KBytes 1.15 Mbits/sec
[ 3] 8.0-10.0 sec 208 KBytes 852 Kbits/sec
[ 3] 10.0-12.0 sec 344 KBytes 1.41 Mbits/sec
[ 3] 12.0-14.0 sec 208 KBytes 852 Kbits/sec
[ 3] 14.0-16.0 sec 232 KBytes 950 Kbits/sec
[ 3] 16.0-18.0 sec 232 KBytes 950 Kbits/sec
[ 3] 18.0-20.0 sec 264 KBytes 1.08 Mbits/sec
[ 3] 0.0-20.1 sec 3.00 MBytes 1.25 Mbits/sec
Server side:
#iperf -s -p 12000
------------------------------------------------------------
Server listening on TCP port 12000
TCP window size: 8.00 KByte (default)
------------------------------------------------------------
[852] local 10.1.1.1 port 12000 connected with 10.6.2.5 port 58316
[ ID] Interval Transfer Bandwidth
[852] 0.0-20.1 sec 3.00 MBytes 1.25 Mbits/sec
Top of the page
UDP tests: (-u), bandwidth settings (-b)
Also check the "Jperf" section.
The UDP tests with the -u argument will give invaluable information about the jitter and the packet loss. If you don't specify the -u argument, Iperf uses TCP.
To keep a good link quality, the packet loss should not go over 1 %. A high packet loss rate will generate a lot of TCP segment retransmissions which will affect the bandwidth.
The jitter is basically the latency variation and does not depend on the latency. You can have high response times and a very low jitter. The jitter value is particularly important on network links supporting voice over IP (VoIP) because a high jitter can break a call.
The -b argument allows the allocation if the desired bandwidth.
Client side:
#iperf -c 10.1.1.1 -u -b 10m
------------------------------------------------------------
Client connecting to 10.1.1.1, UDP port 5001
Sending 1470 byte datagrams
UDP buffer size: 108 KByte (default)
------------------------------------------------------------
[ 3] local 10.6.2.5 port 32781 connected with 10.1.1.1 port 5001
[ 3] 0.0-10.0 sec 11.8 MBytes 9.89 Mbits/sec
[ 3] Sent 8409 datagrams
[ 3] Server Report:
[ 3] 0.0-10.0 sec 11.8 MBytes 9.86 Mbits/sec 2.617 ms 9/ 8409 (0.11%)
Server side:
#iperf -s -u -i 1
------------------------------------------------------------
Server listening on UDP port 5001
Receiving 1470 byte datagrams
UDP buffer size: 8.00 KByte (default)
------------------------------------------------------------
[904] local 10.1.1.1 port 5001 connected with 10.6.2.5 port 32781
[ ID] Interval Transfer Bandwidth Jitter Lost/Total Datagrams
[904] 0.0- 1.0 sec 1.17 MBytes 9.84 Mbits/sec 1.830 ms 0/ 837 (0%)
[904] 1.0- 2.0 sec 1.18 MBytes 9.94 Mbits/sec 1.846 ms 5/ 850 (0.59%)
[904] 2.0- 3.0 sec 1.19 MBytes 9.98 Mbits/sec 1.802 ms 2/ 851 (0.24%)
[904] 3.0- 4.0 sec 1.19 MBytes 10.0 Mbits/sec 1.830 ms 0/ 850 (0%)
[904] 4.0- 5.0 sec 1.19 MBytes 9.98 Mbits/sec 1.846 ms 1/ 850 (0.12%)
[904] 5.0- 6.0 sec 1.19 MBytes 10.0 Mbits/sec 1.806 ms 0/ 851 (0%)
[904] 6.0- 7.0 sec 1.06 MBytes 8.87 Mbits/sec 1.803 ms 1/ 755 (0.13%)
[904] 7.0- 8.0 sec 1.19 MBytes 10.0 Mbits/sec 1.831 ms 0/ 850 (0%)
[904] 8.0- 9.0 sec 1.19 MBytes 10.0 Mbits/sec 1.841 ms 0/ 850 (0%)
[904] 9.0-10.0 sec 1.19 MBytes 10.0 Mbits/sec 1.801 ms 0/ 851 (0%)
[904] 0.0-10.0 sec 11.8 MBytes 9.86 Mbits/sec 2.618 ms 9/ 8409 (0.11%)
Top of the page
Maximum Segment Size (-m argument) display:
The Maximum Segment Size (MSS) is the largest amount of data, in bytes, that a computer can support in a single, unfragmented TCP segment.
It can be calculated as follows:
MSS = MTU - TCP & IP headers
The TCP & IP headers are equal to 40 bytes.
The MTU or Maximum Transmission Unit is the greatest amount of data that can be transferred in a frame.
Here are some default MTU size for different network topology:
Ethernet - 1500 bytes: used in a LAN.
PPPoE - 1492 bytes: used on ADSL links.
Token Ring (16Mb/sec) - 17914 bytes: old technology developed by IBM.
Dial-up - 576 bytes
Generally, a higher MTU (and MSS) brings higher bandwidth efficiency
Client side:
#iperf -c 10.1.1.1 -m
------------------------------------------------------------
Client connecting to 10.1.1.1, TCP port 5001
TCP window size: 16.0 KByte (default)
------------------------------------------------------------
[ 3] local 10.6.2.5 port 41532 connected with 10.1.1.1 port 5001
[ 3] 0.0-10.2 sec 1.27 MBytes 1.04 Mbits/sec
[ 3] MSS size 1448 bytes (MTU 1500 bytes, ethernet)
Here the MSS is not equal to 1500 - 40 but to 1500 - 40 - 12 (Timestamps option) = 1448
Server side:
#iperf -s
Top of the page
Maximum Segment Size (-M argument) settings:
Use the -M argument to change the MSS. (See the previous test for more explanations about the MSS)
#iperf -c 10.1.1.1 -M 1300 -m
WARNING: attempt to set TCP maximum segment size to 1300, but got 536
------------------------------------------------------------
Client connecting to 10.1.1.1, TCP port 5001
TCP window size: 16.0 KByte (default)
------------------------------------------------------------
[ 3] local 10.6.2.5 port 41533 connected with 10.1.1.1 port 5001
[ 3] 0.0-10.1 sec 4.29 MBytes 3.58 Mbits/sec
[ 3] MSS size 1288 bytes (MTU 1328 bytes, unknown interface)
Server side:
#iperf -s
Top of the page
Parallel tests (-P argument):
Use the -P argument to run parallel tests.
Client side:
#iperf -c 10.1.1.1 -P 2
------------------------------------------------------------
Client connecting to 10.1.1.1, TCP port 5001
TCP window size: 16.0 KByte (default)
------------------------------------------------------------
[ 3] local 10.6.2.5 port 41534 connected with 10.1.1.1 port 5001
[ 4] local 10.6.2.5 port 41535 connected with 10.1.1.1 port 5001
[ 4] 0.0-10.1 sec 1.35 MBytes 1.12 Mbits/sec
[ 3] 0.0-10.1 sec 1.35 MBytes 1.12 Mbits/sec
[SUM] 0.0-10.1 sec 2.70 MBytes 2.24 Mbits/sec
Server side:
#iperf -s
Top of the page
Iperf help:
#iperf -h
Usage: iperf [-s|-c host] [options]
iperf [-h|--help] [-v|--version]
Client/Server:
-f
-i
-l
-m
-p
-u
-w
-B
-C
-M
-N
-V --format
--interval
--len
--print_mss
--port
--udp
--window
--bind
--compatibility
--mss
--nodelay
--IPv6Version [kmKM]
#
#[KM]
#
#[KM]
"host"
#
format to report: Kbits, Mbits, KBytes, MBytes
seconds between periodic bandwidth reports
length of buffer to read or write (default 8 KB)
print TCP maximum segment size (MTU - TCP/IP header)
server port to listen on/connect to
use UDP rather than TCP
TCP window size (socket buffer size)
bind to "host", an interface or multicast address
for use with older versions does not sent extra msgs
set TCP maximum segment size (MTU - 40 bytes)
set TCP no delay, disabling Nagle's Algorithm
Set the domain to IPv6
Server specific:
-s
-U
-D --server
--single_udp
--daemon
run in server mode
run in single threaded UDP mode
run the server as a daemon
Client specific:
-b
-c
-d
-n
-r
-t
-F
-I
-L
-P
-T --bandwidth
--client
--dualtest
--num
--tradeoff
--time
--fileinput
--stdin
--listenport
--parallel
--ttl #[KM]
"host"
#[KM]
#
"name"
#
#
# for UDP, bandwidth to send at in bits/sec (default 1 Mbit/sec, implies -u)
run in client mode, connecting to "host"
Do a bidirectional test simultaneously
number of bytes to transmit (instead of -t)
Do a bidirectional test individually
time in seconds to transmit for (default 10 secs)
input the data to be transmitted from a file
input the data to be transmitted from stdin
port to recieve bidirectional tests back on
number of parallel client threads to run
time-to-live, for multicast (default 1)
Miscellaneous:
-h
-v --help
--version
print this message and quit
print version information and quit
The network link is delimited by two hosts running Iperf.
The quality of a link can be tested as follows:
- Latency (response time or RTT): can be measured with the ping command.
- Jitter (latency variation): can be measured with an Iperf UDP test.
- Datagram loss: can be measured with an Iperf UDP test.
The bandwidth is measured through TCP tests.
To be clear, the difference between TCP (Transmission Control Protocol) and UDP (User Datagram Protocol) is that TCP use processes to check that the packets are correctly sent to the receiver whereas with UDP the packets are sent without any checks but with the advantage of being quicker than TCP.
Iperf uses the different capacities of TCP and UDP to provide statistics about network links.
Finally, Iperf can be installed very easily on any UNIX/Linux or Microsoft Windows system. One host must be set as client, the other one as server.
Here is a diagram where Iperf is installed on a Linux and Microsoft Windows machine.
Linux is used as the Iperf client and Windows as the Iperf server. Of course, it is also possible to use two Linux boxes.
screenshot Iperf bandwidth measure client server
Iperf tests:
no arg.
-b
-r
-d
-w
Default settings
Data format
Bi-directional bandwidth
Simultaneous bi-directional bandwidth
TCP Window size
-p, -t, -i
-u, -b
-m
-M
-P
-h Port, timing and interval
UDP tests, bandwidth settings
Maximum Segment Size display
Maximum Segment Size settings
Parallel tests
help
Jperf:
no arg.
-d
-u, -b Default settings
Simultaneous bi-directional bandwidth
UDP tests, bandwidth settings
Default Iperf settings:
Also check "Jperf section.
By default, the Iperf client connects to the Iperf server on the TCP port 5001 and the bandwidth displayed by Iperf is the bandwidth from the client to the server.
If you want to use UDP tests, use the -u argument.
The -d and -r Iperf client arguments measure the bi-directional bandwidths. (See further on this tutorial)
Client side:
#iperf -c 10.1.1.1
------------------------------------------------------------
Client connecting to 10.1.1.1, TCP port 5001
TCP window size: 16384 Byte (default)
------------------------------------------------------------
[ 3] local 10.6.2.5 port 33453 connected with 10.1.1.1 port 5001
[ 3] 0.0-10.2 sec 1.26 MBytes 1.05 Mbits/sec
Server side:
#iperf -s
------------------------------------------------------------
Server listening on TCP port 5001
TCP window size: 8.00 KByte (default)
------------------------------------------------------------
[852] local 10.1.1.1 port 5001 connected with 10.6.2.5 port 33453
[ ID] Interval Transfer Bandwidth
[852] 0.0-10.6 sec 1.26 MBytes 1.03 Mbits/sec
Data formatting: (-f argument)
The -f argument can display the results in the desired format: bits(b), bytes(B), kilobits(k), kilobytes(K), megabits(m), megabytes(M), gigabits(g) or gigabytes(G).
Generally the bandwidth measures are displayed in bits (or Kilobits, etc ...) and an amount of data is displayed in bytes (or Kilobytes, etc ...).
As a reminder, 1 byte is equal to 8 bits and, in the computer science world, 1 kilo is equal to 1024 (2^10).
For example: 100'000'000 bytes is not equal to 100 Mbytes but to 100'000'000/1024/1024 = 95.37 Mbytes.
Client side:
#iperf -c 10.1.1.1 -f b
------------------------------------------------------------
Client connecting to 10.1.1.1, TCP port 5001
TCP window size: 16384 Byte (default)
------------------------------------------------------------
[ 3] local 10.6.2.5 port 54953 connected with 10.1.1.1 port 5001
[ 3] 0.0-10.2 sec 1359872 Bytes 1064272 bits/sec
Server side:
#iperf -s
------------------------------------------------------------
Server listening on TCP port 5001
TCP window size: 8.00 KByte (default)
------------------------------------------------------------
[852] local 10.1.1.1 port 5001 connected with 10.6.2.5 port 33453
[ ID] Interval Transfer Bandwidth
[852] 0.0-10.6 sec 920 KBytes 711 Kbits/sec
Top of the page
Bi-directional bandwidth measurement: (-r argument)
The Iperf server connects back to the client allowing the bi-directional bandwidth measurement. By default, only the bandwidth from the client to the server is measured.
If you want to measure the bi-directional bandwidth simultaneously, use the -d keyword. (See next test.)
Client side:
#iperf -c 10.1.1.1 -r
------------------------------------------------------------
Server listening on TCP port 5001
TCP window size: 85.3 KByte (default)
------------------------------------------------------------
------------------------------------------------------------
Client connecting to 10.1.1.1, TCP port 5001
TCP window size: 16.0 KByte (default)
------------------------------------------------------------
[ 5] local 10.6.2.5 port 35726 connected with 10.1.1.1 port 5001
[ 5] 0.0-10.0 sec 1.12 MBytes 936 Kbits/sec
[ 4] local 10.6.2.5 port 5001 connected with 10.1.1.1 port 1640
[ 4] 0.0-10.1 sec 74.2 MBytes 61.7 Mbits/sec
Server side:
#iperf -s
------------------------------------------------------------
Server listening on TCP port 5001
TCP window size: 8.00 KByte (default)
------------------------------------------------------------
[852] local 10.1.1.1 port 5001 connected with 10.6.2.5 port 54355
[ ID] Interval Transfer Bandwidth
[852] 0.0-10.1 sec 1.15 MBytes 956 Kbits/sec
------------------------------------------------------------
Client connecting to 10.6.2.5, TCP port 5001
TCP window size: 8.00 KByte (default)
------------------------------------------------------------
[824] local 10.1.1.1 port 1646 connected with 10.6.2.5 port 5001
[ ID] Interval Transfer Bandwidth
[824] 0.0-10.0 sec 73.3 MBytes 61.4 Mbits/sec
Top of the page
Simultaneous bi-directional bandwidth measurement: (-d argument)
Also check the "Jperf" section.
To measure the bi-directional bandwidths simultaneousely, use the -d argument. If you want to test the bandwidths sequentially, use the -r argument (see previous test).
By default (ie: without the -r or -d arguments), only the bandwidth from the client to the server is measured.
Client side:
#iperf -c 10.1.1.1 -d
------------------------------------------------------------
Server listening on TCP port 5001
TCP window size: 85.3 KByte (default)
------------------------------------------------------------
------------------------------------------------------------
Client connecting to 10.1.1.1, TCP port 5001
TCP window size: 16.0 KByte (default)
------------------------------------------------------------
[ 5] local 10.6.2.5 port 60270 connected with 10.1.1.1 port 5001
[ 4] local 10.6.2.5 port 5001 connected with 10.1.1.1 port 2643
[ 4] 0.0-10.0 sec 76.3 MBytes 63.9 Mbits/sec
[ 5] 0.0-10.1 sec 1.55 MBytes 1.29 Mbits/sec
Server side:
#iperf -s
------------------------------------------------------------
Server listening on TCP port 5001
TCP window size: 8.00 KByte (default)
------------------------------------------------------------
[852] local 10.1.1.1 port 5001 connected with 10.6.2.5 port 60270
------------------------------------------------------------
Client connecting to 10.6.2.5, TCP port 5001
TCP window size: 8.00 KByte (default)
------------------------------------------------------------
[800] local 10.1.1.1 port 2643 connected with 10.6.2.5 port 5001
[ ID] Interval Transfer Bandwidth
[800] 0.0-10.0 sec 76.3 MBytes 63.9 Mbits/sec
[852] 0.0-10.1 sec 1.55 MBytes 1.29 Mbits/sec
Top of the page
TCP Window size: (-w argument)
The TCP window size is the amount of data that can be buffered during a connection without a validation from the receiver.
It can be between 2 and 65,535 bytes.
On Linux systems, when specifying a TCP buffer size with the -w argument, the kernel allocates double as much as indicated.
Client side:
#iperf -c 10.1.1.1 -w 2000
WARNING: TCP window size set to 2000 bytes. A small window size
will give poor performance. See the Iperf documentation.
------------------------------------------------------------
Client connecting to 10.1.1.1, TCP port 5001
TCP window size: 3.91 KByte (WARNING: requested 1.95 KByte)
------------------------------------------------------------
[ 3] local 10.6.2.5 port 51400 connected with 10.1.1.1 port 5001
[ 3] 0.0-10.1 sec 704 KBytes 572 Kbits/sec
Server side:
#iperf -s -w 4000
------------------------------------------------------------
Server listening on TCP port 5001
TCP window size: 3.91 KByte
------------------------------------------------------------
[852] local 10.1.1.1 port 5001 connected with 10.6.2.5 port 51400
[ ID] Interval Transfer Bandwidth
[852] 0.0-10.1 sec 704 KBytes 570 Kbits/sec
Top of the page
Communication port (-p), timing (-t) and interval (-i):
The Iperf server communication port can be changed with the -p argument. It must be configured on the client and the server with the same value, default is TCP port 5001.
The -t argument specifies the test duration time in seconds, default is 10 secs.
The -i argument indicates the interval in seconds between periodic bandwidth reports.
Client side:
#iperf -c 10.1.1.1 -p 12000 -t 20 -i 2
------------------------------------------------------------
Client connecting to 10.1.1.1, TCP port 12000
TCP window size: 16.0 KByte (default)
------------------------------------------------------------
[ 3] local 10.6.2.5 port 58316 connected with 10.1.1.1 port 12000
[ 3] 0.0- 2.0 sec 224 KBytes 918 Kbits/sec
[ 3] 2.0- 4.0 sec 368 KBytes 1.51 Mbits/sec
[ 3] 4.0- 6.0 sec 704 KBytes 2.88 Mbits/sec
[ 3] 6.0- 8.0 sec 280 KBytes 1.15 Mbits/sec
[ 3] 8.0-10.0 sec 208 KBytes 852 Kbits/sec
[ 3] 10.0-12.0 sec 344 KBytes 1.41 Mbits/sec
[ 3] 12.0-14.0 sec 208 KBytes 852 Kbits/sec
[ 3] 14.0-16.0 sec 232 KBytes 950 Kbits/sec
[ 3] 16.0-18.0 sec 232 KBytes 950 Kbits/sec
[ 3] 18.0-20.0 sec 264 KBytes 1.08 Mbits/sec
[ 3] 0.0-20.1 sec 3.00 MBytes 1.25 Mbits/sec
Server side:
#iperf -s -p 12000
------------------------------------------------------------
Server listening on TCP port 12000
TCP window size: 8.00 KByte (default)
------------------------------------------------------------
[852] local 10.1.1.1 port 12000 connected with 10.6.2.5 port 58316
[ ID] Interval Transfer Bandwidth
[852] 0.0-20.1 sec 3.00 MBytes 1.25 Mbits/sec
Top of the page
UDP tests: (-u), bandwidth settings (-b)
Also check the "Jperf" section.
The UDP tests with the -u argument will give invaluable information about the jitter and the packet loss. If you don't specify the -u argument, Iperf uses TCP.
To keep a good link quality, the packet loss should not go over 1 %. A high packet loss rate will generate a lot of TCP segment retransmissions which will affect the bandwidth.
The jitter is basically the latency variation and does not depend on the latency. You can have high response times and a very low jitter. The jitter value is particularly important on network links supporting voice over IP (VoIP) because a high jitter can break a call.
The -b argument allows the allocation if the desired bandwidth.
Client side:
#iperf -c 10.1.1.1 -u -b 10m
------------------------------------------------------------
Client connecting to 10.1.1.1, UDP port 5001
Sending 1470 byte datagrams
UDP buffer size: 108 KByte (default)
------------------------------------------------------------
[ 3] local 10.6.2.5 port 32781 connected with 10.1.1.1 port 5001
[ 3] 0.0-10.0 sec 11.8 MBytes 9.89 Mbits/sec
[ 3] Sent 8409 datagrams
[ 3] Server Report:
[ 3] 0.0-10.0 sec 11.8 MBytes 9.86 Mbits/sec 2.617 ms 9/ 8409 (0.11%)
Server side:
#iperf -s -u -i 1
------------------------------------------------------------
Server listening on UDP port 5001
Receiving 1470 byte datagrams
UDP buffer size: 8.00 KByte (default)
------------------------------------------------------------
[904] local 10.1.1.1 port 5001 connected with 10.6.2.5 port 32781
[ ID] Interval Transfer Bandwidth Jitter Lost/Total Datagrams
[904] 0.0- 1.0 sec 1.17 MBytes 9.84 Mbits/sec 1.830 ms 0/ 837 (0%)
[904] 1.0- 2.0 sec 1.18 MBytes 9.94 Mbits/sec 1.846 ms 5/ 850 (0.59%)
[904] 2.0- 3.0 sec 1.19 MBytes 9.98 Mbits/sec 1.802 ms 2/ 851 (0.24%)
[904] 3.0- 4.0 sec 1.19 MBytes 10.0 Mbits/sec 1.830 ms 0/ 850 (0%)
[904] 4.0- 5.0 sec 1.19 MBytes 9.98 Mbits/sec 1.846 ms 1/ 850 (0.12%)
[904] 5.0- 6.0 sec 1.19 MBytes 10.0 Mbits/sec 1.806 ms 0/ 851 (0%)
[904] 6.0- 7.0 sec 1.06 MBytes 8.87 Mbits/sec 1.803 ms 1/ 755 (0.13%)
[904] 7.0- 8.0 sec 1.19 MBytes 10.0 Mbits/sec 1.831 ms 0/ 850 (0%)
[904] 8.0- 9.0 sec 1.19 MBytes 10.0 Mbits/sec 1.841 ms 0/ 850 (0%)
[904] 9.0-10.0 sec 1.19 MBytes 10.0 Mbits/sec 1.801 ms 0/ 851 (0%)
[904] 0.0-10.0 sec 11.8 MBytes 9.86 Mbits/sec 2.618 ms 9/ 8409 (0.11%)
Top of the page
Maximum Segment Size (-m argument) display:
The Maximum Segment Size (MSS) is the largest amount of data, in bytes, that a computer can support in a single, unfragmented TCP segment.
It can be calculated as follows:
MSS = MTU - TCP & IP headers
The TCP & IP headers are equal to 40 bytes.
The MTU or Maximum Transmission Unit is the greatest amount of data that can be transferred in a frame.
Here are some default MTU size for different network topology:
Ethernet - 1500 bytes: used in a LAN.
PPPoE - 1492 bytes: used on ADSL links.
Token Ring (16Mb/sec) - 17914 bytes: old technology developed by IBM.
Dial-up - 576 bytes
Generally, a higher MTU (and MSS) brings higher bandwidth efficiency
Client side:
#iperf -c 10.1.1.1 -m
------------------------------------------------------------
Client connecting to 10.1.1.1, TCP port 5001
TCP window size: 16.0 KByte (default)
------------------------------------------------------------
[ 3] local 10.6.2.5 port 41532 connected with 10.1.1.1 port 5001
[ 3] 0.0-10.2 sec 1.27 MBytes 1.04 Mbits/sec
[ 3] MSS size 1448 bytes (MTU 1500 bytes, ethernet)
Here the MSS is not equal to 1500 - 40 but to 1500 - 40 - 12 (Timestamps option) = 1448
Server side:
#iperf -s
Top of the page
Maximum Segment Size (-M argument) settings:
Use the -M argument to change the MSS. (See the previous test for more explanations about the MSS)
#iperf -c 10.1.1.1 -M 1300 -m
WARNING: attempt to set TCP maximum segment size to 1300, but got 536
------------------------------------------------------------
Client connecting to 10.1.1.1, TCP port 5001
TCP window size: 16.0 KByte (default)
------------------------------------------------------------
[ 3] local 10.6.2.5 port 41533 connected with 10.1.1.1 port 5001
[ 3] 0.0-10.1 sec 4.29 MBytes 3.58 Mbits/sec
[ 3] MSS size 1288 bytes (MTU 1328 bytes, unknown interface)
Server side:
#iperf -s
Top of the page
Parallel tests (-P argument):
Use the -P argument to run parallel tests.
Client side:
#iperf -c 10.1.1.1 -P 2
------------------------------------------------------------
Client connecting to 10.1.1.1, TCP port 5001
TCP window size: 16.0 KByte (default)
------------------------------------------------------------
[ 3] local 10.6.2.5 port 41534 connected with 10.1.1.1 port 5001
[ 4] local 10.6.2.5 port 41535 connected with 10.1.1.1 port 5001
[ 4] 0.0-10.1 sec 1.35 MBytes 1.12 Mbits/sec
[ 3] 0.0-10.1 sec 1.35 MBytes 1.12 Mbits/sec
[SUM] 0.0-10.1 sec 2.70 MBytes 2.24 Mbits/sec
Server side:
#iperf -s
Top of the page
Iperf help:
#iperf -h
Usage: iperf [-s|-c host] [options]
iperf [-h|--help] [-v|--version]
Client/Server:
-f
-i
-l
-m
-p
-u
-w
-B
-C
-M
-N
-V --format
--interval
--len
--print_mss
--port
--udp
--window
--bind
--compatibility
--mss
--nodelay
--IPv6Version [kmKM]
#
#[KM]
#
#[KM]
"host"
#
format to report: Kbits, Mbits, KBytes, MBytes
seconds between periodic bandwidth reports
length of buffer to read or write (default 8 KB)
print TCP maximum segment size (MTU - TCP/IP header)
server port to listen on/connect to
use UDP rather than TCP
TCP window size (socket buffer size)
bind to "host", an interface or multicast address
for use with older versions does not sent extra msgs
set TCP maximum segment size (MTU - 40 bytes)
set TCP no delay, disabling Nagle's Algorithm
Set the domain to IPv6
Server specific:
-s
-U
-D --server
--single_udp
--daemon
run in server mode
run in single threaded UDP mode
run the server as a daemon
Client specific:
-b
-c
-d
-n
-r
-t
-F
-I
-L
-P
-T --bandwidth
--client
--dualtest
--num
--tradeoff
--time
--fileinput
--stdin
--listenport
--parallel
--ttl #[KM]
"host"
#[KM]
#
"name"
#
#
# for UDP, bandwidth to send at in bits/sec (default 1 Mbit/sec, implies -u)
run in client mode, connecting to "host"
Do a bidirectional test simultaneously
number of bytes to transmit (instead of -t)
Do a bidirectional test individually
time in seconds to transmit for (default 10 secs)
input the data to be transmitted from a file
input the data to be transmitted from stdin
port to recieve bidirectional tests back on
number of parallel client threads to run
time-to-live, for multicast (default 1)
Miscellaneous:
-h
-v --help
--version
print this message and quit
print version information and quit
Subscribe to:
Posts (Atom)