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Configuration Guide - Device Management

CloudEngine 8800, 7800, 6800, and 5800 V200R005C10

This document describes the configurations of Device Management, including device status query, hardware management, Information Center Configuration, NTP, Synchronous Ethernet Configuration, Fault Management Configuration, Energy-Saving Management Configuration, Performance Management Configuration, Maintenance Assistant Configuration, and OPS Configuration.
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Establishing the Master-Slave Hierarchy

Establishing the Master-Slave Hierarchy

During master-slave hierarchy establishment, 1588v2 selects the grandmaster clock (GMC) and determines the master and slave ports.

Process of Establishing the Master-Slave Hierarchy

In 1588v2, ports receive and send Announce messages to exchange data sets and port state machine information. Best Master Clock (BMC) algorithm compares the data sets and port state machine information to determine the master-slave hierarchy.

The process of establishing the master-slave hierarchy is as follows:

  1. The local device receives and processes Announce messages from the peer port.
  2. The local device uses the BMC algorithm to determine the GMC and recommended port state, namely, master, slave, or passive state.
  3. The local device updates data sets based on the recommended port state.
  4. The local device determines the actual port state based on the port state machine and establishes the master-slave hierarchy based on the recommended state and state decision event. The state decision event is generated when an Announce message is received or when no Announce message is received within the specified timeout period. When the interval at which a port receives an Announce message is larger than the Announce message timeout period, the state of this port is set to master.

BMC Algorithm

The BMC algorithm is used to select the GMC and determine port states in a PTP domain. This algorithm compares the data sets carried in the Announce messages exchanged between clock nodes to select the GMC and determine port states.

The BMC algorithm compares the following attributes in Announce messages in sequence:

  • Priority1: indicates clock priority 1 value. The value is configurable and ranges from 0 to 255. A smaller value indicates a higher priority.
  • Clock-Class: indicates the clock class. A smaller value indicates a higher clock class.
  • Clock-Accuracy: defines clock accuracy. A smaller value indicates higher accuracy.
  • OffsetScaledLogVariance: defines clock stability. A smaller value indicates higher stability.
  • Priority2: indicates clock priority 2 value. The value is configurable and ranges from 0 to 255. A smaller value indicates a higher priority.

In the BMC algorithm, Priority1 of each candidate time source is compared first, then Clock-Class, Clock-Accuracy, OffsetScaledLogVariance, and Priority2. If Priority1 of candidate time sources is the same, Clock-Class is compared, and so on. The time source with the highest priority, class, and accuracy is selected as the GMC.

The preceding attributes can be changed to affect system master clock selection and finally select the clock signals to receive. The BMC algorithm can allocate PTP clock sources and implement protection switching.

Updated: 2019-04-20

Document ID: EDOC1100075362

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