CFM Traffic Field Indicator for PBB-TE Mismatch Detection
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Solution Overview
Problem
Current PBB-TE systems face challenges in detecting and reporting mismatches between bridge/selector positions in 1:1 bidirectional protection switching, which can lead to incomplete or incorrect protection switching, and existing solutions like the APS protocol are complex and unnecessary for this specific environment.
Innovation Solution
A Traffic field indicator is introduced in the Flags field of CFM messages to monitor and report mismatches automatically, using a reserved bit to indicate traffic status, allowing for immediate detection and adjustment of CCM intervals to save bandwidth and provide in-band signaling support.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the APS protocol is used to detect mismatch in bridge/selector positions, then mismatch detection capability is improved, but device complexity increases
Solution Approach 1:
The invention extracts the essential mismatch detection function from the complex APS protocol and implements it directly within the CFM message structure. By utilizing the existing CFM messaging infrastructure and adding a simple Traffic field to indicate working/protection path status, the patent eliminates the need for separate APS protocol processing while maintaining reliable mismatch detection between bridge and selector positions
Solution Approach 2:
The CFM message structure is enhanced to serve multiple functions: continuity checking, fault detection, and mismatch detection. The Traffic field in the CFM message simultaneously indicates the current active path (working or protection) and enables mismatch detection when bridge and selector positions differ, consolidating multiple OAM functions into a single messaging framework
2Speed
If CCM messages are sent at high frequency to detect mismatches, then detection speed is improved, but bandwidth consumption increases
Solution Approach 1:
The patent utilizes the periodic transmission of CCM messages already established in the CFM framework. Rather than increasing transmission frequency, the solution leverages the existing periodic CCM exchanges and enhances them with the Traffic field to carry mismatch detection information, maintaining energy efficiency while achieving constant monitoring through the information carried in each periodic message
Data Source
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AI summary
A method in a Maintenance Association Endpoint, MEP (110), for controlling traffic between a first network element (23) and a second network element (24) connected by a working Traffic Engineering Service Instance, TESI (21), and a protection TESI (22). The first network element sets a Traffic field (41) in a Connectivity Check Message, CCM, sent to the second network element. The Traffic field may be set by utilizing a reserved bit within a Flags field (14') of the CCM. The Traffic field indicates which TESI is being utilized to transport the traffic. The second network element takes action to control the traffic based upon a value of the Traffic field in the received CCM. When the Traffic field value in the received CCM does not match the Traffic field value in CCMs sent from the second network element for a predefined period of time, the second network element moves the traffic from its current TESI to the other TESI.