手动设置：
LGY-2960-29.11(config)#clock timezone BJ +8
LGY-2960-29.11#clock set 15:40:09 23 december 2017
NTP：
ntp server 10.10.101.21
注：ntp服务器可以用AD
时间戳
service timestamps debug datetime msec localtime year
service timestamps log datetime msec localtime year