Ethernet-PON ONU Frame Filtering via LLID Matching
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Solution Overview
Problem
Existing Ethernet-PON systems face compatibility issues with upper bridges due to the broadcast nature of downstream data and the need for excessive bandwidth consumption and complex frame multiplexing in point-to-point communication environments, where upstream frames are not efficiently forwarded to the intended ONUs.
Innovation Solution
A communication node system that utilizes an LLID register, preamble generator, CRC generator, and filter to create and manage transport frames, ensuring point-to-point communication by selectively forwarding frames based on LLID matching, thereby reducing bandwidth consumption and simplifying frame multiplexing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If all frames are broadcast to all ONUs in the PON to ensure point-to-point communication compatibility with upper bridges, then compatibility with existing bridges is improved, but down-stream bandwidth consumption increases excessively
Solution Approach 1:
The patent extracts the LLID filtering function from the upper bridge layer and implements it directly in the ONU's emulation sublayer. Each ONU compares the LLID in received frames with its own LLID and discards mismatched frames before they consume bandwidth, thereby maintaining bridge compatibility while eliminating excessive bandwidth usage.
Solution Approach 2:
The LLID acts as an intermediary identifier that enables the upper bridge to operate in a point-to-multipoint environment without modification. By inserting LLID into the Ethernet frame structure, the system mediates between the broadcast nature of PON and the point-to-point expectations of traditional bridges, allowing selective frame delivery without full broadcasting.
2Adaptability or versatility
If multiple logical MAC layers are provided for each ONU to handle frame multiplexing, then point-to-point communication is enabled, but the frame multiplexing process becomes complicated
Solution Approach 1:
The patent segments the frame handling process into two independent stages: LLID-based filtering at the emulation sublayer and standard Ethernet MAC processing at the upper layer. This segmentation eliminates the need for complex inter-MAC layer multiplexing by resolving frame destination identification at a lower level, simplifying the overall multiplexing process.
Solution Approach 2:
The emulation sublayer performs preliminary frame filtering based on LLID comparison before frames reach the MAC layer. By pre-processing frames and discarding those not intended for the local ONU, the system eliminates the need for complex post-MAC multiplexing operations, reducing overall system complexity.
3Adaptability or versatility
If frames are returned to the PON interface for broadcasting to all ONUs, then point-to-point communication is supported, but bandwidth is wasted on frames not intended for specific ONUs
Solution Approach 1:
Each ONU performs self-service frame filtering by comparing received frame LLIDs with its own LLID. This self-service mechanism eliminates the need for centralized frame routing control and prevents bandwidth waste by discarding unrelated frames at the source, improving overall bandwidth utilization efficiency.
Data Source
AI summary
A communication node system for an Ethernet-PON includes: an LLID register for storing an LLID being an allocated identifier; a preamble generator for generating a PON preamble; a CRC generator for generating a CRC for the preamble; a transmission connector for combining transport data with the CRC-including preamble to generate a transport frame, and forwarding the transport frame; a reception connector for receiving the frame and dividing the frame into a preamble and received data; a filter for extracting an LLID from the preamble, comparing the extracted LLID with the LLID stored in the register, and selectively filtering the extracted LLID; and a received frame generator for discarding the received data, or combining the received data with the preamble to generate a received frame.