Quasi Slave Nodes for Passive PTP Timing Distribution
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Solution Overview
Problem
Conventional methods for timing distribution in packet-switched networks, such as Metro Ethernet networks, face limitations due to the need for additional PTP slave functions and bandwidth consumption, especially when dealing with multiple slave nodes, which can exceed the capacity of a single PTP master node.
Innovation Solution
Implementing virtual or quasi slave nodes that passively process existing PTP-type packet streams to retrieve timing information without generating additional traffic, allowing for clock and phase recovery, packet delay measurement, and PDV monitoring at intermediate network nodes, thereby reducing the load on master nodes and conserving bandwidth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional PTP slave functions are deployed at each network node for timing distribution, then timing synchronization is achieved, but the master node capacity is exceeded and bandwidth is consumed
Solution Approach 1:
The patent introduces an intermediary mechanism where existing network nodes (routers, switches) act as passive observers of PTP traffic rather than active participants requiring slave functions. These intermediaries monitor timing packets and extract synchronization information without being formally registered as PTP slaves, thereby extending timing distribution capability without increasing master node capacity or consuming additional bandwidth.
Solution Approach 2:
The patent enables multiple virtual copies of slave functionality to be created at existing network nodes by passively copying and processing PTP timing packets. Instead of requiring physical slave devices at each location, the system creates virtual slave instances that derive timing information from intercepted PTP streams, allowing scalable deployment without additional hardware or bandwidth allocation.
2Adaptability or versatility
If additional PTP slave functions are added to support multiple slave nodes, then timing distribution coverage is improved, but bandwidth consumption increases
Solution Approach 1:
The patent makes existing network nodes universal by enabling them to perform multiple functions: their primary networking role plus passive PTP monitoring. By allowing routers and switches to simultaneously handle their conventional traffic while also observing PTP streams for timing information, the system extends timing distribution coverage without requiring dedicated bandwidth for additional slave functions.
Solution Approach 2:
The patent enables network nodes to self-configure timing monitoring capabilities by automatically detecting and processing PTP packets in their traffic stream. Nodes autonomously extract timing information without requiring explicit configuration or additional resource allocation, allowing the system to scale coverage organically as PTP traffic naturally flows through the network infrastructure.
3Measurement precision
If PTP protocol is used for timing distribution, then timing accuracy is improved, but the system requires additional slave functions that consume resources
Solution Approach 1:
The patent extracts the essential timing measurement function from the complete PTP slave implementation. Instead of requiring full PTP slave functionality with its associated resource consumption, the system extracts only the critical capability of observing PTP packets and deriving timing information, separating this lightweight function from the resource-intensive complete slave implementation.
Solution Approach 2:
The patent applies partial action by implementing only the necessary portion of PTP slave functionality required for timing accuracy. Rather than deploying full slave nodes with complete PTP stacks, the system implements minimal processing to capture timing packets and extract synchronization data, achieving sufficient timing accuracy with reduced resource consumption.
Data Source
AI summary
A method and a network node are provided, for distributing timing information in a packet-switched network. The method is characterized in that at least one network node used as a quasi slave node is located at a path extending between a master node and a slave node. The method comprising a step of calculating the timing at that network node, by passively processing packets belonging to a PTP-type packet stream being exchanged between the master node and the slave node and conveyed via that intermediate network node operating as a quasi slave.