SONET Frame Mapper Buffer Reduction via Packet Segmentation
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Solution Overview
Problem
Current transmission systems face challenges in managing diverse packet lengths and bandwidth allocations, leading to increased buffer sizes and potential 'head of line blocking' in SONET frame mappers, which complicates device design and reduces efficiency.
Innovation Solution
The system divides packets into fixed-length segments and multiplexes them using a TDM scheduler, shifting the packet-to-TDM unit conversion from the SONET frame mapper to the QoS engine, and allocates SPI4.2 interfaces to manage channel identification and bandwidth efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If packets are directly mapped in SONET frames without segmentation, then device complexity is reduced, but buffer sizes increase and head of line blocking occurs
Solution Approach 1:
The patent segments packets into fixed-length TDM units (e.g., 53-byte units) before mapping to SONET frames. This segmentation is performed by a TDM scheduler in the QoS engine, which divides variable-length packets into uniform segments that can be efficiently buffered and mapped. The segmentation resolves the contradiction by enabling smaller buffers while maintaining manageable device complexity through structured data flow.
Solution Approach 2:
The patent performs packet segmentation and TDM multiplexing in advance, before the data reaches the SONET frame mapper. The QoS engine pre-processes packets by dividing them into fixed-length segments and organizing them into TDM frames, so that the SONET frame mapper receives pre-organized data requiring minimal buffering. This preliminary action eliminates the need for large buffers at the mapper while maintaining system manageability.
2Quantity of substance
If packets are segmented into fixed-length units and multiplexed early, then buffer sizes are reduced, but device complexity increases due to additional processing components
Solution Approach 1:
The patent introduces a TDM scheduler as an intermediary component between the packet source and the SONET frame mapper. This intermediary performs the segmentation and multiplexing functions, acting as a mediator that transforms variable-length packets into fixed-length TDM units. The intermediary resolves the contradiction by enabling buffer size reduction while concentrating the processing complexity in a dedicated component rather than distributing it throughout the system.
Solution Approach 2:
The patent implements dynamic segmentation where packets are divided into fixed-length TDM units based on configurable parameters. The TDM scheduler dynamically manages the segmentation process, adjusting to different packet sizes and traffic patterns while maintaining consistent output unit sizes. This dynamic approach enables buffer size reduction while managing processing complexity through adaptive, parameter-driven operation.
3Productivity
If variable-length packets are handled directly in SONET mapping, then bandwidth allocation is simple, but head of line blocking occurs and transmission efficiency decreases
Solution Approach 1:
The patent segments variable-length packets into fixed-length TDM units (e.g., 53-byte units) that are then multiplexed into TDM frames before SONET mapping. This segmentation eliminates head of line blocking because each segment can be independently processed and transmitted according to its timing slot, rather than waiting for the entire variable-length packet to be ready. The fixed-length segmentation enables continuous flow and improves transmission efficiency.
Solution Approach 2:
The patent implements periodic TDM multiplexing where fixed-length segments are assigned to regular time slots in the TDM frame structure. This periodic allocation of transmission slots to different segments eliminates head of line blocking by ensuring that each segment has a guaranteed periodic transmission opportunity, regardless of when it arrived or how long the original packet was. This periodic action improves productivity by maintaining continuous transmission flow.
Data Source
AI summary
A transmission apparatus that receives plural packets and transmits a frame of a synchronous network, includes a multiplexing part that divides, in segment units, the plural packets, each segment having a predetermined length, and multiplexes the segments to generate a data stream signal; a transmitting part that transmits the data stream signal to a mapping part; and the mapping part that maps the data stream signal in the frame of the synchronous network.