Configuring NTP Operating Modes

Context

The following NTP operating modes are supported by devices:

Operating Mode	Usage Scenario	Configuration
Unicast client/server mode	Within a synchronization subnet, the unicast client/server mode operates on a higher stratum. In this mode, the server IP address must be obtained in advance.	Only the client requires configuration. The server needs to be configured with only an NTP primary clock. The client can be synchronized to the server. The server cannot be synchronized to the client.
Symmetric peer mode	Within a synchronization subnet, symmetric peer mode operates on a lower stratum. In this mode, symmetric active and passive peers can be synchronized with each other.	Only the symmetric active peer requires configuration. In symmetric peer mode, symmetric peers of higher strata are synchronized to symmetric peers of lower strata.
Broadcast mode	In broadcast mode, clock synchronization can be implemented when: The IP addresses of servers or symmetric peers are not determined. When the clocks of a large number of devices require synchronization on a network.	Relevant commands need to be run on both the server and client. The client can be synchronized to the server. The server cannot be synchronized to the client.
Multicast mode	Multicast mode applies to high-speed networks with multiple clients but do not require high precision. In a typical scenario, one or more clock servers on the network periodically send multicast packets to clients, and the clients synchronize time based on the multicast packets.	Relevant commands need to be run on both the server and client. The client can be synchronized to the server. The server cannot be synchronized to the client.
Manycast mode	Manycast mode applies to scenarios where servers are scattered throughout a network. Once discovered, the client can synchronize with the closest manycast server. Manycast mode applies to scenarios where servers are unstable and network clients do not require reconfiguration if server characteristics or configuration change.	Relevant commands need to be run on both the server and client. Note that the client can be synchronized to the server. The server cannot be synchronized to the client.

Switches can function as both an NTP server and NTP client.

If a source address from which NTP packets are sent is specified on the server, the address must be identical to the server IP address of the client. If these addresses differ, the client will be unable to process the NTP packets sent by the server. This will result in clock synchronization failure.

Procedure

Unicast Client/Server Mode

In the unicast client/server mode, only the client and the NTP primary clock on the server require configuration.

Once the server clock is synchronized, the server can function as a clock server. Other devices can then be synchronized to that server. When the clock stratum of the server is greater than or equal to the clock stratum of the client, the client will not synchronize to the server.

To configure multiple servers, run the ntp-service unicast-server command repeatedly. The optimal clock is that which the client selects as the preferred clock.

Configure the unicast client.
1. Run system-view
  The system view is displayed.
2. Run
  - ntp-service unicast-server ip-address [ version number | authentication-keyid key-id | source-interface interface-type interface-number | preference | vpn-instance vpn-instance-name | maxpoll max-number | minpoll min-number | burst | iburst | preempt | port port-number ] ^*
    
    An NTP server with a specified IPv4 address is configured.
  - ntp-service unicast-server ipv6 ipv6-address [ authentication-keyid key-id | source-interface interface-type interface-number | preference | vpn-instance vpn-instance-name | maxpoll max-number | minpoll min-number | burst | iburst | preempt | port port-number ] ^*
    
    An NTP server with a specified IPv6 address is configured.
  The value of ip-address or ipv6-address is the IP address of the NTP server. It can be a host address but cannot be a broadcast or multicast address.
  
  To specify the authentication-keyid parameter, see Configuring NTP Authentication.
  
  If the port parameter is specified, specify the same port number on the server using the ntp-service port port-value command.
Symmetric Peer Mode

Only the IP address of the symmetric passive peer on the symmetric active peer requires specification. Both symmetric peers use this IP address when exchanging NTP packets.

Either the symmetric active or symmetric passive peer must be in the synchronized state. They cannot be synchronized without one in synchronized state.

To configure multiple symmetric passive peers, run the ntp-service unicast-peer command repeatedly. When multiple symmetric passive peers are configured for a symmetric active peer, the synchronization direction follows the rule that symmetric peers of higher strata are synchronized with symmetric peers of lower strata.

Configure the symmetric active peer.
1. Run system-view
  The system view is displayed.
2. Run
  - ntp-service unicast-peer ip-address [ version number | authentication-keyid key-id | source-interface interface-type interface-number | preference | vpn-instance vpn-instance-name | maxpoll max-number | minpoll min-number | preempt | port port-number ]^*
    The NTP peer with a specified IPv4 address is configured.
  - ntp-service unicast-peer ipv6 ipv6-address [ authentication-keyid key-id | source-interface interface-type interface-number | preference | vpn-instance vpn-instance-name | maxpoll max-number | minpoll min-number | preempt | port port-number ]^*
    The NTP peer with a specified IPv6 address is configured.
  The value of ip-address or ipv6-address must be a unicast address.
  
  To specify the authentication-keyid parameter, see Configuring NTP Authentication.
  
  If the port parameter is specified, specify the same port number on the passive peer using the ntp-service port port-value command.
Broadcast Mode

Broadcast mode can be used only on LANs.

The broadcast client can be synchronized with the broadcast server only after the clock of the broadcast server is synchronized.

Configure the NTP broadcast server.
1. Run system-view
  The system view is displayed.
2. Run interface interface-type interface-number
  The interface for sending NTP broadcast packets is specified, and the interface view is displayed.
3. Run ntp-service broadcast-server [ version number | authentication-keyid key-id | port port-number ] ^*
  The local switch is configured as the NTP broadcast server.
  
  To specify the authentication-keyid parameter, see Configuring NTP Authentication.
  
  If the port parameter is specified, specify the same port number on the broadcast client using the ntp-service port port-value command.
Configure the NTP broadcast client.
1. Run system-view
  The system view is displayed.
2. Run interface interface-type interface-number
  The interface for receiving NTP broadcast packets is specified, and the interface view is displayed.
3. Run ntp-service broadcast-client
  The local switch is configured as the NTP broadcast client.
Multicast Mode

The multicast client can synchronize with the multicast server only after the clock of the multicast server is synchronized. A maximum of 128 multicast servers can be configured on the device.

A maximum of 1024 multicast clients can be configured, and a maximum of 128 multicast clients can operate simultaneously.

Configure the NTP multicast server.
1. Run system-view
  The system view is displayed.
2. Run interface interface-type interface-number
  The interface for sending NTP multicast packets is specified, and the interface view is displayed.
3. Run
  - ntp-service multicast-server [ ip-address ] [ version number | authentication-keyid key-id | ttl ttl-number | port port-number ] ^*
    The local switch is configured as the NTP multicast server on an IPv4 network.
  - ntp-service multicast-server ipv6 [ ipv6-address ] [ authentication-keyid key-id | ttl ttl-number | port port-number ] ^*
    The local switch is configured as the NTP multicast server on an IPv6 network.
  To specify the authentication-keyid parameter, see Configuring NTP Authentication.
  
  If the port parameter is specified, specify the same port number on the multicast client using the ntp-service port port-value command.
Configure the NTP multicast client.
1. Run system-view
  The system view is displayed.
2. Run interface interface-type interface-number
  The interface for receiving NTP multicast packets is specified, and the interface view is displayed.
3. Run ntp-service multicast-client [ ip-address | ipv6 [ ipv6-address ] ]
  The local switch is configured as the NTP multicast client.
Manycast Mode
Configure the NTP manycast server.
1. Run system-view
  The system view is displayed.
2. Run interface interface-type interface-number
  The interface for receiving NTP manycast packets is specified, and the interface view is displayed.
3. Run ntp-service manycast-server [ ip-address | ipv6 [ ipv6-address ] ]
  The local switch is configured as the NTP manycast server.
Configure the NTP manycast client.
1. Run system-view
  The system view is displayed.
2. Run interface interface-type interface-number
  The interface for sending NTP manycast packets is specified, and the interface view is displayed.
3. Run ntp-service manycast-client [ ip-address | ipv6 [ ipv6-address ] ] [ authentication-keyid key-id | ttl ttl-number | port port-number ] ^*
  The local switch is configured as the NTP manycast client.
  
  To specify the authentication-keyid parameter, see Configuring NTP Authentication.
  
  If the port parameter is specified, specify the same port number on the manycast server using the ntp-service port port-value command.