Inter-Packet Gap Clock Synchronization for Ethernet TDM
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Solution Overview
Problem
Ethernet networks face challenges in providing sufficient Quality of Service (QoS) for time division multiplexed (TDM) data due to jitter and data loss issues, particularly in supporting stringent requirements of voice traffic in public switched telephone networks, and existing enhancements fail to combine flexibility with high QoS requirements.
Innovation Solution
The introduction of Huawei-Enhanced (HE) Ethernet operational modes, including frequency-synchronized communication mode (H-Sync) and frequency-synchronized and phase-aligned communication mode (H-TDM), which utilize inter-packet gaps for timestamp transmission, enabling deterministic data transfer and supporting high priority data without contention, and an overlay synchronous timeslot scheme for precise synchronization and phase alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Ethernet packets are transported through the network with resource arbitration and buffers at nodes, then Quality of Service for TDM data is improved, but network complexity increases
Solution Approach 1:
The patent extracts the synchronization function from the data packets themselves by utilizing the inter-packet gap period for timestamp transmission. This separation allows Ethernet to maintain its simple, decentralized nature while incorporating TDM synchronization capabilities, avoiding the need for complex resource arbitration and buffering mechanisms.
Solution Approach 2:
The inter-packet gap, which is traditionally an idle period in Ethernet communication, is given a dual function: it serves both as a separator between data packets and as a carrier for synchronization timestamps. This multi-functionality enables QoS for TDM data without adding separate synchronization infrastructure or increasing network complexity.
2Reliability
If resource arbitration and buffers are implemented at nodes, then data loss is reduced, but delay increases
Solution Approach 1:
The patent implements preliminary synchronization by embedding timestamps in the inter-packet gaps before the actual data packets arrive at the destination. This allows the receiving node to pre-prepare for incoming TDM data with known timing characteristics, eliminating the need for buffering delays while preventing data loss through proactive clock synchronization.
3Reliability
If Ethernet enhancements such as circuit emulation are used, then jitter requirements are met, but flexibility is lost
Solution Approach 1:
The patent introduces dynamic operational modes that allow the Ethernet network to adapt its behavior based on traffic requirements. The system can dynamically switch between standard Ethernet operation and TDM-synchronized operation, maintaining flexibility while meeting jitter requirements when needed. The inter-packet gap synchronization mechanism can be activated or deactivated based on whether TDM traffic is present.
Data Source
AI summary
A network component comprising a processor configured to receive a data stream from an upstream node, wherein the data stream comprises a plurality of Ethernet packets and a synchronization request comprising a timestamp, synchronize a clock with the timestamp, and transmit a response to the upstream node, wherein the data stream has the same bandwidth as a second data stream that does not have the synchronization request and the timestamp.