Протестировал LBD на прошивке v1.84.B009 
LBD Global Settings
 ---------------------------
 Status           : Enabled
 Mode             : Port Based
 Interval         : 1 sec
 Recover Time     : 77 sec
 Trap State       : None
 Function Version : 4.04
Index Date       Time     Log Text
----- ---------- -------- ------------------------------------------------------
16    0000-00-00 00:13:42 Port 2 link up, 100Mbps  FULL duplex
15    0000-00-00 00:13:39 Port 2 LBD port recovered. Loop detection restarted
14    0000-00-00 00:12:23 Port 2 link down
13    0000-00-00 00:12:22 Port 2 LBD loop occurred. Port blocked
Обновите ПО. 
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