====== Test Multicast Join (iperf) ======
<color #db5f0b>Jun 2017</color>
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We can test if our device can join a multicast using a tool called <color #ed1c24>iperf</color>. <color #ed1c24>iperf</color> is not installed by default, so you will have to add it by us9ing:
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    yum install iperf
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If you see the following error when trying to install iperf:
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<file>
Loaded plugins: fastestmirror
base                                                                                  | 3.6 kB  00:00:00
extras                                                                                | 3.4 kB  00:00:00
updates                                                                               | 3.4 kB  00:00:00
(1/4): base/7/x86_64/group_gz                                                         | 156 kB  00:00:00
(2/4): extras/7/x86_64/primary_db                                                     | 110 kB  00:00:00
(3/4): updates/7/x86_64/primary_db                                                    | 2.7 MB  00:00:00
(4/4): base/7/x86_64/primary_db                                                       | 5.7 MB  00:00:01
Determining fastest mirrors
 * base: anorien.csc.warwick.ac.uk
 * extras: mirrors.clouvider.net
 * updates: mirrors.coreix.net
No package iperf available.
Error: Nothing to do
</file>
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The last line that states <color #ed1c24>Error: Nothing to do</color> means that CentOS doesn't know where to get iperf from (not in the repositories that CentOS is aware of) then you can run the following.
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    yum install epel-release
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This will install the relevant repositories for CentOS to find iperf. Once again you can run:
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    yum install iperf
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Once installed, you can use <color #ed1c24>iperf</color> to connect to a multicast stream by using the following syntax.
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    iperf -s -u -B 239.0.200.1 -p 10001 -i 1
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==== Example output ====
<file>
------------------------------------------------------------
Server listening on UDP port 10001
Binding to local address 239.0.200.1
Joining multicast group  239.0.200.1
Receiving 1470 byte datagrams
UDP buffer size: 16.0 MByte (default)
------------------------------------------------------------
[  3] local 239.0.200.1 port 10001 connected with 10.27.250.1 port 10000
[ ID] Interval       Transfer     Bandwidth        Jitter   Lost/Total Datagrams
[  3]  0.0- 1.0 sec   775 KBytes  6.35 Mbits/sec  1472463338220.286 ms 1195888311/1195888914 (1e+02%)
[  3]  0.0- 1.0 sec  595 datagrams received out-of-order
[  3]  1.0- 2.0 sec   775 KBytes  6.35 Mbits/sec  1590510364122.785 ms    0/    0 (-nan%)
[  3]  1.0- 2.0 sec  603 datagrams received out-of-order
[  3]  2.0- 3.0 sec   775 KBytes  6.35 Mbits/sec  1477144115030.008 ms    0/    0 (-nan%)
[  3]  2.0- 3.0 sec  603 datagrams received out-of-order
[  3]  3.0- 4.0 sec   775 KBytes  6.35 Mbits/sec  1472946740641.257 ms    0/    0 (-nan%)
[  3]  3.0- 4.0 sec  603 datagrams received out-of-order
[  3]  4.0- 5.0 sec   775 KBytes  6.35 Mbits/sec  1264384362197.854 ms    6/    7 (86%)
</file>