Cause thanks to dell support was having spanning-tree guard loop configured per switch. 
hi all,   I am trying to find connected devices to the dell switch I have here using show mac address-table and show arp, however, I have a problem the 'show mac address-table' lists the mac address for the device on port 27 as 00BB.C1CC.3A97 but the show arp tells me the mac address is B40E.xxyy.CCF6 the correct mac address.... I am trying to get the IP, Mac address and port number for each devices so i can programmatically detect the devices i am after... I have tried clearing the mac address table with no luck (via web GUI).. Any know what is going on??
Dell N2000 Series - Incorrect Mac address-table