Cisco ASR 9000 Series User Configuration Manual page 228

Configuring Poll-Based Associations
Use the 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.
When a networking device is operating in the symmetric active mode, it polls its assigned time-serving hosts
for the current time and it responds to polls by its hosts. Because this is a peer-to-peer relationship, the host
also retains time-related information about the local networking device that it is communicating with. This
mode should be used when there are several 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 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.
When the router polls several other devices for the time, the router selects one device with which to synchronize.
Note To configure a peer-to-peer association between the router and another device, you must also configure
the router as a peer on the other device.
You can configure multiple peers and servers, but you cannot configure a single IP address as both a peer
and a server at the same time.
To change the configuration of a specific IP address from peer to server or from server to peer, use the
no form of the peer or server command to remove the current configuration before you perform the
new configuration. If you do not remove the old configuration before performing the new configuration,
the new configuration does not overwrite the old configuration.
SUMMARY STEPS
1. configure
2. ntp
3. server ip-address [version number] [key key-id] [minpoll interval] [maxpoll interval] [source type
interface-path-id] [prefer] [burst] [iburst]
4. peer ip-address [version number] [key key-id] [minpoll interval] [maxpoll interval] [source type
interface-path-id] [prefer]
5. Use one of the following commands:
DETAILED STEPS
Command or Action
Step 1 configure
Step 2
ntp
Example:
RP/0/RSP0/CPU0:router(config)# ntp
Cisco ASR 9000 Series Aggregation Services Router System Management Configuration Guide, Release 5.1.x
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• end
• commit
Purpose
Enters NTP configuration mode.
Implementing NTP