##########
Cisco NXOS
在5.2版本之后，NTP支持多实例。默认为在default vdc下配置，除非拟单独配置了其他vdc的ntp配置。
只有一个vdc同步时间，默认为default vdc。其他vdc只可以用来作为NTP server对外提供服务。要修改用来同步时间的vdc，命令为： clock protocol ntp vdc vdc-id
关于VRF，默认使用default vrf
在default vdc下
ntp enable
ntp server x.x.x.x use-vrf Mgmt
(Optional) ntp source x.x.x.x
(Optional) ntp source-interface eth x
ntp logging
ntp distribute #用来同步配置
ntp commit #需要配置提交，同时可解除cfs的lock
ntp abort #取消NTP配置的更改
标准配置梳理：
ntp enable
clock timezone BJT 8 0
ntp server x.x.x.x use-vrf Mgmt
ntp logging
ntp distribute
ntp commit 需要配置提交
备注：https://www.cisco.com/c/en/us/td/docs/switches/datacenter/sw/5_x/nx-os/system_management/configuration/guide/sm_nx_os_cg/sm_2cfs.html#27128
CFS可用来同步的配置包括
Table 4-1 CFS-Supported Applications
| Application | Default State |
|---|---|
##########
Cisco IOS
!--- This router has a hardware calendar. !--- To configure a system as an !--- authoritative time source for a network !--- based on its hardware clock (calendar), !--- use the clock calendar-valid global !--- configuration command. Notice later that !--- NTP will be allowed to update the calendar !--- and Cisco IOS will be configured to be an !--- NTP master clock source. !--- Cisco IOS will then obtain its clock from !--- the hardware calendar. clock calendar-valid !--- This allows NTP to update the hardware !--- calendar chip. ntp update-calendar
!--- When the system sends an NTP packet, the !--- source IP address is normally set to the !--- address of the interface through which the !--- NTP packet is sent. !--- Change this to use loopback0. ntp source Loopback0 总结：标准配置
clock timezone BJT 8
clock calendar-valid
ntp source GigabitEthernet1/X
ntp update-calendar
ntp server x.x.x.x prefer
##########
ASR
ntp asr有可能是先NTP，然后进去配置相关项