This section describes how to configure time attributes for 1588v2 packets. 1588v2 routers exchange Announce, Sync, and Delay or Pdelay packets to send time information and maintain 1588v2 connections. You can set the interval at which a 1588v2 interface sends Announce, Sync, and Delay or Pdelay packets and the maximum number of Announce packet timeouts. Using the default time attribute values is recommended.
Context
Two devices exchange
Announce packets to determine the master/slave relationship. The master
device sends Sync packets to notify the slave device of time signal
parameters and uses a delay measurement mechanism to achieve time
signals accuracy.
If routers exchange 1588v2 packets frequently and consume a lot of bandwidth resources, increase the interval value. If the time synchronization accuracy is low, reduce the interval value.
Announce packets
To set the maximum number of Announce packets that a 1588v2 interface fails to receive consecutively, run the ptp announce receipt-timeout command. If the 1588v2 interface on a device fails to receive a specified number of Announce packets, the interface status becomes Master, and the device stops attempting to synchronize the time with other 1588v2 devices. The device uses the BMC algorithm to select a clock source and synchronize the time with the clock source. Increase receipt-timeout to reduce the clock source switching frequency; reduce receipt-timeout to switch clock sources. Using the default value is recommended.
Sync packets
The master interface periodically sends multicast Sync packets.
The time when the Sync packets can be stamped into the
Sync packets if the one-step timestamping mode is used or into Follow_Up
packets if the two-step timestamping mode is used. To specify a timestamping
mode, run the ptp clock-step { one-step | two-step } command.
Delay or Pdelay packets
A router uses a delay measurement mechanism to send request packets and receive response packets from its remote router. The router uses timestamps carried in the packets to correct time signals.
Perform the following steps on each 1588v2 router:
Procedure
- Configure time attributes for Announce packets.
- Run system-view
The system view is displayed.
- Run interface interface-type interface-number
The interface view is displayed.
- Run ptp announce-interval announce-interval
The interval at which the interface sends Announce packets is set. The following formula applies:
Interval = 2n x 1/1024s, where n equals to announce-interval
Remote timeout period of receiving Announce packets = Remotely configured receipt-timeout x Local interval at which Announce packets are sent
- Run ptp announce receipt-timeout receipt-timeout
The maximum number of Announce packets that the interface fails to receive is set. If the interface fails to consecutively receive the specified maximum number of Announce packets, the interface enters the Master state.
Local timeout period of receiving Announce packets = Locally configured receipt-timeout x Remote interval at which Announce packets are sent
- Run commit
The configuration is committed.
- Configure time attributes for Sync packets.
- Run system-view
The system view is displayed.
- Run interface interface-type interface-number
The interface view is displayed.
- Run ptp sync-interval sync-interval
The interval at which the interface sends Sync packets is set. The following formula applies:
Interval = 2n x 1/1024s, where n equals to sync-interval
- Run commit
The configuration is committed.
- Configure time attributes for Delay or Pdelay packets.
- Run system-view
The system view is displayed.
- Run interface interface-type interface-number
The interface view is displayed.
- Run ptp min-delayreq-interval min-delayreq-interval
The interval at which the interface sends Delay_Req packets is set. The following formula applies:
Interval = 2n x 1/1024s, where n equals to min-delayreq-interval
- Run ptp min-pdelayreq-interval min-pdelayreq-interval
The interval at which the interface sends Pdelay_Req packets is set. The following formula applies:
Interval = 2n x 1/1024s, where n equals to min-pdelayreq-interval
- Run commit
The configuration is committed.