how to know reason of interface went down

what is configuration for adding in CMBD ,SMC , OBS for cisco cisco switch 

Hello team,The utilization for the interface is not normalized what is reason 

TenGigabitEthernet2/0/24 is down, line protocol is down (notconnect)   what could be the possible solution

 i see, in most of organization   ospf  neighborship is  on loopback interface  ,i dont understand why we  require physical port & cable connectivity ,what is use of it. can any  one explian in deatils