Core-Switch-1#show clock
Core-Switch-1#show ntp status
Core-Switch-1#conf t
Core-Switch-1(config)# clock timezone GMT +8   //设置时区
Core-Switch-1(config)#service timestamps debug datetime msec localtime show-timezone   //debug 时间为本地时间
Core-Switch-1(config)#service timestamps log datetime msec localtime show-timezone    //log 时间为本地时间
Core-Switch-1(config)#exit
Core-Switch-1# clock set 13:51:00 Sep 7 2011 //设置时间
或通过NTP服务器时间同步：
Core-Switch-1#ntp server 192.168.0.254 key 8888     //注：8888是指ntp服务器的Key值
Core-Switch-1#wr
Core-Switch-1#sh log

默认情况下日志消息不包括日期和时间戳。
service timestamps {debug | log } uptime
service timestamps {debug | log } datetime [mesc] [localtime] [show-timezone] [year]
debug 参数 在调试输出时包括时间戳
log 参数 在每种日志消息中添加一个时间戳
uptime 在消息中包括路由器开机以来的时间
0w2d: #SYS-5-CONFIG_I : Configured from console by console
0w2d    开机后0周2天
datetime 显示准确的日期和时间 UTC 格式   标准格式 MM DD HH:MM:SS
datetime后面可以跟一些参数
mesc 消息中包括毫秒信息
localtime 显示基于本地配置的时区时间
show-timezone 输出包括时区名称
year 输出包括年份信息

未设置时间前：
#sh log
4w0d: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/6, changed state to up
4w0d: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/6, changed state to down
4w0d: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/6, changed state to up
4w1d: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/5, changed state to down
4w1d: %LINK-3-UPDOWN: Interface FastEthernet0/5, changed state to down
4w1d: %LINK-3-UPDOWN: Interface FastEthernet0/5, changed state to up
4w1d: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/5, changed state to up
4w1d: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/3, changed state to down
4w1d: %LINK-3-UPDOWN: Interface FastEthernet0/3, changed state to down
4w1d: %LINK-3-UPDOWN: Interface FastEthernet0/3, changed state to up
4w1d: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/3, changed state to up

设置后
#sh log
.Sep  7 05:59:22: %SYS-6-CLOCKUPDATE: System clock has been updated from 13:59:22 BJ Wed Sep 7 2011 to 05:59:22 UTC Wed Sep 7 2011, configured from console by wht on vty2 (172.16.100.10).
.Sep  7 13:59:23: %SYS-6-CLOCKUPDATE: System clock has been updated from 05:59:23 UTC Wed Sep 7 2011 to 13:59:23 GMT Wed Sep 7 2011, configured from console by wht on vty2 (172.16.100.10).
.Sep  7 13:59:24: %SYS-5-CONFIG_I: Configured from console by wht on vty2 (172.16.100.10)
.Sep  7 13:58:00: %SYS-6-CLOCKUPDATE: System clock has been updated from 14:00:05 GMT Wed Sep 7 2011 to 13:58:00 GMT Wed Sep 7 2011, configured from console by wht on vty2 (172.16.100.10).