@Bruce I think you might be on to something here, the Force10s I think are running MST but to be sure, I forced them. The 2960 may well have not had PVST turned off and if I capture the traffic coming into the 355 port that it is connected to I see the below: 23:36:06.808535 STP 802.1d, Config, Flags [none], bridge-id 80ca.00:1f:27:98:25:80.8019, length 42 23:36:08.871307 STP 802.1d, Config, Flags [none], bridge-id 8061.00:1f:27:98:25:80.8019, length 42 23:36:08.873530 STP 802.1d, Config, Flags [none], bridge-id 80ca.00:1f:27:98:25:80.8019, length 42 23:36:08.888086 STP 802.1d, Config, Flags [none], bridge-id 80de.00:1f:27:98:25:80.8019, length 42 23:36:10.797447 STP 802.1d, Config, Flags [none], bridge-id 8064.00:1f:27:98:25:80.8019, length 42 23:36:10.812630 STP 802.1d, Config, Flags [none], bridge-id 8067.00:1f:27:98:25:80.8019, length 42 23:36:10.823630 STP 802.1d, Config, Flags [none], bridge-id 80d3.00:1f:27:98:25:80.8019, length 42 23:36:12.742462 STP 802.1d, Config, Flags [none], bridge-id 8004.00:1f:27:98:25:80.8019, length 42 23:36:12.743131 STP 802.1d, Config, Flags [none], bridge-id 8060.00:1f:27:98:25:80.8019, length 42 23:36:14.741285 STP 802.1d, Config, Flags [none], bridge-id 8005.00:1f:27:98:25:80.8019, length 42 23:36:14.741311 STP 802.1d, Config, Flags [none], bridge-id 800a.00:1f:27:98:25:80.8019, length 42 23:36:14.741335 STP 802.1d, Config, Flags [none], bridge-id 801e.00:1f:27:98:25:80.8019, length 42 23:36:14.741360 STP 802.1d, Config, Flags [none], bridge-id 805a.00:1f:27:98:25:80.8019, length 42 23:36:14.770695 STP 802.1d, Config, Flags [none], bridge-id 80d3.00:1f:27:98:25:80.8019, length 42 23:36:14.771391 STP 802.1d, Config, Flags [none], bridge-id 80de.00:1f:27:98:25:80.8019, length 42 23:36:16.775371 STP 802.1d, Config, Flags [none], bridge-id 801e.00:1f:27:98:25:80.8019, length 42 23:36:16.775398 STP 802.1d, Config, Flags [none], bridge-id 8061.00:1f:27:98:25:80.8019, length 42 23:36:16.776242 STP 802.1d, Config, Flags [none], bridge-id 8064.00:1f:27:98:25:80.8019, length 42 23:36:16.786084 STP 802.1d, Config, Flags [none], bridge-id 80a9.00:1f:27:98:25:80.8019, length 42 23:36:18.774561 STP 802.1d, Config, Flags [none], bridge-id 8002.00:1f:27:98:25:80.8019, length 42 23:36:18.774589 STP 802.1d, Config, Flags [none], bridge-id 8003.00:1f:27:98:25:80.8019, length 42 23:36:18.774613 STP 802.1d, Config, Flags [none], bridge-id 8004.00:1f:27:98:25:80.8019, length 42 23:36:18.774635 STP 802.1d, Config, Flags [none], bridge-id 8005.00:1f:27:98:25:80.8019, length 42 23:36:18.774658 STP 802.1d, Config, Flags [none], bridge-id 800a.00:1f:27:98:25:80.8019, length 42 23:36:18.774683 STP 802.1d, Config, Flags [none], bridge-id 805a.00:1f:27:98:25:80.8019, length 42 As you can see, plenty of STP messages. I cannot ping it at the moment, it is one of the affected devices, but it looks like it needs a tweak. I will test tomorrow by disabling the port on the 355 to see if it then stabalises.
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