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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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1588v2 Messages

1588v2 Messages

On a PTP network, all clocks are organized into a master-slave hierarchy, with the grandmaster clock at the top of the hierarchy. Time synchronization is implemented through the exchange of 1588v2 messages. A slave clock calculates its time offset and link delay compared with the master clock based on the timestamp carried in a 1588v2 message to synchronize its local clock with the master clock in the hierarchy.

In Figure 6-3, 1588v2 messages are timestamped on the physical chip instead of on an upper-layer network, maximizing timestamp accuracy. Compared with the Network Time Protocol (NTP), 1588v2 ensures higher accuracy.
Figure 6-3 Timestamping in 1588v2 messages

Message Types

1588v2 messages are classified into event messages and general messages depending on timestamps:
  • Event message

    It is used to calculate the time offset and link delay between the master and slave clocks. Event messages are tagged with a timestamp when reaching or leaving a port. Event messages include Sync, Delay_Req, Pdelay_Req, and Pdelay_Resp messages.

  • General message

    It is used to establish a master-slave hierarchy and request and send time information. General messages are not tagged with timestamps. General messages include Announce, Follow_Up, Delay_Resp, Pdelay_Resp_Follow_Up, Management, and Signaling messages. Currently, switches do not support Management and Signaling messages.

Message Format

1588v2 messages can be encapsulated in Layer 2 and Layer 3 packets for transmission. 1588v2 messages can be classified into MAC-encapsulated and UDP-encapsulated messages based on the link type used for 1588v2 message transmission:
  • MAC-encapsulated messages

    When 1588v2 messages are transmitted on a Layer 2 link, use MAC encapsulation with the Ethernet Type 0x88F7. In this situation, you can set the VLAN ID and 802.1p priority to be carried in 1588v2 messages.

    Figure 6-4 Untagged MAC-encapsulated messages

    Figure 6-5 Tagged MAC-encapsulated messages

  • UDP-encapsulated messages

    When 1588v2 messages are transmitted on a Layer 3 link, the destination UDP port number is 319 (for non-Announce messages) or 320 (for Announce messages). In this situation, you can set the VLAN ID, 802.1p priority, and Differentiated Services Code Point (DSCP) priority to be carried in 1588v2 messages.

    Figure 6-6 Untagged UDP-encapsulated messages

    Figure 6-7 Tagged UDP-encapsulated messages

Updated: 2019-04-20

Document ID: EDOC1100075362

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