NTP

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NTP Poll modes

•Client mode

When a networking device is operating in the client mode, it polls its assigned time serving hosts for the current time.

The host will not capture or use any time information sent by the local client device.

Use the ntp server command to individually specify the time serving hosts that you want your networking device to consider synchronizing with and to set your networking device to operate in the client mode.

•Symmetric active mode

Polls its assigned time serving hosts for the current time and it responds to polls by its hosts. Since this is a peer-to-peer relationship, the host will also retain time-related information about the local networking device that it is communicating with. This mode should be used when there is a number of mutually redundant servers that are interconnected via diverse network paths. Most Stratum 1 and stratum 2 servers on the Internet today adopt this form of network setup. Use the ntp peer command to individually specify the time serving hosts that you want your networking device to consider synchronizing with and to set your networking device to operate in the symmetric active mode.

Broadcast mode

Listens for NTP broadcast packets

Set on the interface rather than globally

Configuration commands Client

ntp server {IP ADDRESS} - Client mode

ntp peer {IP ADDRESS} - Symmetric Active mode

Server

NTP master {stratum}

Broadcast

* Server = ntp broadcast

* Client = ntp broadcast client