Hitless Resizing Optical Transport Network Tributary Slots
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Solution Overview
Problem
Existing data transport networks face challenges in dynamically resizing network connections without packet loss, particularly for packet-based data with varying bandwidth requirements, as current methods like VCAT/LCAS are complex and inefficient, leading to resource wastage and high complexity.
Innovation Solution
A method for controlling dynamic hitless resizing in data transport networks involves receiving a connection resize control signal at each node along the network path, adding or removing tributary slots in a synchronized manner between nodes, and adjusting the transport data rate, allowing for flexible bandwidth adjustments without packet loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If VCAT/LCAS is used for dynamic bandwidth adjustment, then bandwidth flexibility is improved, but system complexity increases significantly
Solution Approach 1:
The patent extracts the complex LCAS protocol functionality and replaces it with a simplified resize control signal mechanism. Instead of implementing the full VCAT/LCAS framework with its complex status reporting and acknowledgment protocols, the invention uses a dedicated resize control signal that directly commands bandwidth changes, eliminating the need for complex status tracking and acknowledgment exchanges between network elements.
Solution Approach 2:
The patent employs a simple, lightweight resize control signal that can be generated and discarded after use, replacing the need for persistent complex state management. The resize control signal carries only the essential bandwidth change information without requiring maintenance of complex protocol states, making it a disposable control mechanism that significantly reduces system complexity.
2Adaptability or versatility
If connection is terminated and re-initiated for resizing, then bandwidth change is achieved, but packet loss occurs
Solution Approach 1:
The patent applies preliminary action by sending the resize control signal to prepare the network path for bandwidth change before actually modifying the data transmission. The network elements receive and process the resize control signal in advance, allocating or releasing tributary slots beforehand, so that when the bandwidth change is executed, the path is already prepared and no packets are lost.
Solution Approach 2:
The patent maintains continuity of useful action by keeping the connection active throughout the resizing process. Instead of terminating and re-initiating the connection, the resize control signal enables continuous data transmission while the bandwidth is being adjusted. The tributary slots are dynamically allocated or released without interrupting the data flow, ensuring uninterrupted service.
3Productivity
If multiple tributary slots are allocated for bandwidth increase, then bandwidth capacity is improved, but resource wastage occurs if not properly synchronized
Solution Approach 1:
The patent implements feedback through the resize control signal mechanism that provides confirmation and status information back to the signal source. When tributary slots are allocated or released in response to the resize control signal, the system can track and confirm the actual bandwidth changes, ensuring that resources are properly managed and no wastage occurs due to unsynchronized or incomplete allocation.
Solution Approach 2:
The patent merges the control of multiple tributary slots into a single resize control signal. Instead of managing each tributary slot independently with separate control mechanisms, the resize control signal simultaneously controls the allocation or release of multiple slots, ensuring they are adjusted together in a synchronized manner. This prevents resource wastage that would occur if slots were allocated at different times or states.
Data Source
Figure 1a~1b
Figure 2
Figure 3a
AI summary
The invention relates to techniques for controlling a dynamic hitless resizing in data transport networks. According to a method aspect of the invention, a network connection comprises M tributary slots defined in a payload area of a higher order transport scheme of the data transport network and the method comprises the steps of receiving a connection resize control signal at each of the nodes along the path of the network connection; adding at each node along the path in response to the connection resize control signal a second set of N tributary slots to the first set of the M tributary slots, such that the network connection comprises M+N tributary slots; and increasing, after M+N tributary slots are available for the network connection at each node along the path, a transport data rate of the network connection.