Synchronization Mechanism - H3C SR6600-X Configuration Manual

b. Clock node with higher time class.
c. Clock node with higher time accuracy.
d. Clock node with higher priority 2.
e. Clock node with a smaller port ID (containing clock number and port number).
The master nodes, member nodes, master ports, and subordinate ports are determined during the
process. Then a spanning tree with the GM as the root is generated for the PTP domain.
2. The master node periodically sends announce messages to the member nodes. If the member
nodes do not receive announce messages from the master node, they consider the master node
invalid, and they start to elect another GM.
Clock source type
A clock node of a device can use one of the following clock sources:
Local clock—38.88 MHz clock signals generated by a crystal oscillator inside the clock monitoring
•
module.
• ToD clock—Clock signals generated by a ToD clock. The signals are sent to the clock monitoring
module through a ToD interface (ToD0 or ToD1) on the MPU and then sent to all cards by the clock
monitoring module.
The clock node determines which type of clock source to use.

Synchronization mechanism

PTP sends synchronization messages between the master and member nodes to determine the delay
measurement. The one-way delay time is the average of the delay of the transmit and receive messages.
The member nodes use this delay time to adjust their local clocks.
PTP defines the following transmission delay measurement mechanisms:
• Request_Response.
Peer Delay.
•
Both mechanisms assume a symmetric communication path.
Request_Response
The Request_Response mechanism includes the following modes:
• Single-step mode—t1 is carried in the Sync message, and no Follow_Up message is sent.
Two-step mode—t1 is carried in the Follow_Up message.
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