Metro Transport Networking Timing Distribution via 66b Blocks
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Solution Overview
Problem
Existing timing techniques in Metro Transport Networking (MTN) are inefficient as they require packet-aware circuitry and cannot implement multiple Precision Time Protocol (PTP) timing islands for various clients, and timing information cannot be switched with client paths, limiting synchronization capabilities.
Innovation Solution
The use of 66b blocks from 64b/66b encoding for timing, where a specific block with an O-code is detected to sample a clock and transmit timing information via PTP messages, allowing for client-specific and switchable timing distribution at the path layer in MTN networks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If PTP timing is implemented at the FlexE layer, then timing distribution is achieved, but multiple PTP timing islands cannot be implemented for various clients and timing information cannot be switched with client paths
Solution Approach 1:
The timing distribution system is segmented into per-path timing islands rather than a single global timing domain. Each client path can have its own timing characteristics and synchronization parameters, allowing independent timing control for different clients while sharing the same physical FlexE infrastructure.
Solution Approach 2:
The solution moves from section-layer timing (affecting all clients) to path-layer timing (affecting individual clients). This dimensional shift enables timing information to be associated with and switched along with specific client paths, providing client-specific timing without requiring separate physical infrastructure.
2Reliability
If packet-aware circuitry is used for timing, then PTP messages can be processed, but device complexity increases and timing efficiency decreases
Solution Approach 1:
The timing function is extracted from the packet processing plane and implemented at the physical layer using 66b blocks. By removing timing processing from packet-aware circuitry and placing it in the physical layer, the system achieves timing accuracy without requiring complex packet classification and processing capabilities.
Solution Approach 2:
The solution replaces packet-based software/timestamp mechanisms with physical layer block-based timing. Instead of using packet headers and software processing, the system uses dedicated 66b blocks that can be processed by simple physical layer circuitry, substituting complex packet processing with simpler physical signal processing.
3Productivity
If FlexE timing is used, then timing distribution is achieved, but the periodic multi-frame reference bounds the amount of sync messages
Solution Approach 1:
The system transitions from static periodic timing references to dynamic on-demand timing distribution. Instead of being constrained by fixed multi-frame periods, timing information can be transmitted dynamically at any moment when needed, allowing flexible and adaptive synchronization that responds to actual network conditions and client requirements.
Data Source
AI summary
Systems and methods for timing over a Metro Transport Networking (MTN) path include detecting a specific block in a stream of blocks, wherein each block is encoded based on a line code, and sampling an output of a clock to determine a timestamp reference based on detection of the specific block, and transmitting timing information based on the timestamp reference. The specific block can be a control block. The timing information can be transmitted via a Precision Time Protocol (PTP) message. The timing information can be transmitted via a plurality of subsequent specific blocks.