ODUflex Bandwidth Resizing Synchronization via Overhead Signaling
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Solution Overview
Problem
In telecommunications, particularly in Optical Transport Networks (OTN), existing methods for changing the rate of ODUflex client signals during the Hitless Adjustment of ODUflex (HAO) protocol face challenges such as buffer overflow/underflow issues due to asynchronous rate changes across intermediate nodes, leading to instability and non-deterministic network behavior.
Innovation Solution
A method where a rate change indication signal is sent through the overhead of the client signal to coordinate rate changes across all nodes in the signal path, allowing them to adjust their output rates in parallel at a nominal rate, thereby maintaining buffer stability and transit latency within predetermined ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If asynchronous rate changes are implemented at intermediate nodes during HAO protocol operation, then each node can independently adjust its output rate, but buffer overflow and underflow issues occur leading to instability
Solution Approach 1:
The patent implements a feedback mechanism where a rate change indication signal is sent through the overhead of the client signal to coordinate rate changes across all nodes. Each node monitors this signal and adjusts its output rate in parallel at a nominal rate only when synchronized, preventing buffer overflow and underflow by ensuring all nodes change rates simultaneously rather than asynchronously
Solution Approach 2:
The rate change indication signal carried in the overhead area acts as an intermediary that coordinates between source node and intermediate nodes. This mediator ensures all nodes receive the rate change command and execute it in parallel, resolving the contradiction between independent rate adjustment and buffer stability
2Reliability
If rate changes are coordinated across all nodes using a rate change indication signal, then buffer stability is maintained, but additional overhead signaling is required
Solution Approach 1:
The patent reuses the existing overhead area of the client signal for dual purposes: carrying normal client data and simultaneously conveying rate change indication signals. This multi-functionality approach maintains buffer stability through coordinated rate changes without adding separate dedicated signaling channels, thus avoiding excessive device complexity
3Speed
If intermediate nodes independently adjust output rates without coordination, then faster rate changes are possible, but non-deterministic network behavior occurs
Solution Approach 1:
The source node sends a rate change indication signal through the overhead area before actually changing the client signal rate. This preliminary action allows all intermediate nodes to prepare for the rate change in advance and execute it simultaneously at the predetermined nominal rate, ensuring deterministic network behavior while maintaining fast rate adjustment
Data Source
AI summary
Methods and systems are provided for controlling elements in a signal path of a communication network to accommodate changes in the rate of a client signal. In particular, during the bandwidth resizing (BWR) portion of ITU-T Recommendation G.7044 Hitless Adjustment of ODUflex(GFP) protocol (HAO), the nodes in the chain along the ODUflex(GFP) signal path change their output rates in parallel such that FIFO over/underflow is avoided in the nodes. Certain embodiments provide mechanisms to synchronize and stabilize the nodes in a verifiable manner.