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--- wiki:show_connected_multicasts [2017/06/19 20:27] – created walkeradmin
+++ wiki:show_connected_multicasts [2023/03/09 22:35] (current) – external edit 127.0.0.1
@@ Line 1: / Line 1: @@
 ====== Show Connected Multicasts ======
+<color #db5f0b>Jun 2017</color>
+\\
+\\
+----
+This page discusses two tools. <color #ed1c24>netstat</color> and <color #ed1c24>ip</color>
+\\
+\\
+To show if an interface is actively listening to any multicast streams, we can show this by using the <color #ed1c24>netstat</color> command: (<color #ed1c24>netstat -ng</color>)
+\\
+\\
+If <color #ed1c24>netstat</color> is not available, you will have to install <color #ed1c24>net-tools</color> (yum install net-tools)
+\\
+<file>
+netstat -ng
+IPv6/IPv4 Group Memberships
+Interface       RefCnt Group
+--------------- ------ ---------------------
+lo              1      224.0.0.1
+eth2            4      239.0.200.1
+eth2            1      224.0.0.1
+eth3            1      224.0.0.1
+eth4            1      224.0.0.1
+eth5            1      224.0.0.1
+eth0            1      224.0.0.1
+eth1            1      224.0.0.1
+lo              1      ff02::1
+eth2            1      ff02::1
+eth3            1      ff02::1
+eth4            1      ff02::1
+eth5            1      ff02::1
+eth0            1      ff02::1
+eth1            1      ff02::1
+</file>
+\\
+This is a packager (v8) that I have setup a service on. That service is an ABR service containing four streams, so the line:
+\\
+\\
+<color #ed1c24>eth2            4      239.0.200.1</color>
+\\
+\\
+Is interesting to me, I can see that from address 239.0.200.1 (the MFEL multicast output) Interface 2 is connected to four multicasts.
+\\
+\\
+Another tool we can use is <color #ed1c24>ip maddr</color> this gives more information.
+\\
+<file>
+:      lo
+        inet  224.0.0.1
+        inet6 ff02::1
+:      eth2
+        link  01:00:5e:00:c8:01
+        link  33:33:00:00:00:01
+        link  01:00:5e:00:00:01
+        inet  239.0.200.1 users 4
+        inet  224.0.0.1
+        inet6 ff02::1
+:      eth3
+        link  01:00:5e:00:00:01
+        inet  224.0.0.1
+        inet6 ff02::1
+:      eth4
+        link  33:33:00:00:00:01
+        link  01:00:5e:00:00:01
+        inet  224.0.0.1
+        inet6 ff02::1
+:      eth5
+        link  01:00:5e:00:00:01
+        inet  224.0.0.1
+        inet6 ff02::1
+:      eth0
+        link  33:33:00:00:00:01
+        link  01:00:5e:00:00:01
+        inet  224.0.0.1
+        inet6 ff02::1
+:      eth1
+        link  01:00:5e:00:00:01
+        inet  224.0.0.1
+        inet6 ff02::1
+</file>
+\\
+\\
+On interface 2, we can see the same information, but just formatted in a different way:
+\\
+\\
+eth2\\
+link  01:00:5e:00:c8:01\\
+link  33:33:00:00:00:01\\
+link  01:00:5e:00:00:01\\
+<color #ed1c24>        inet  239.0.200.1 users 4</color>\\
+inet  224.0.0.1\\
+inet6 ff02::1\\
+\\
+\\