Staggered CCM Transmission Windows for Ethernet MEP Congestion
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Solution Overview
Problem
In Ethernet Connectivity Fault Management, as the number of Maintenance Association End Points (MEPs) increases, the burst of Continuity Check Messages (CCM) can overwhelm network queues, leading to packet drops, especially when all MEPs transmit simultaneously or synchronize their transmission timers, causing network congestion and packet loss.
Innovation Solution
Each MEP is configured to determine a unique transmission window by dividing the CCM interval by the maximum number of MEPs in the maintenance association, using a synchronized clock, such as Network Time Protocol (NTP), to ensure only one MEP transmits a CCM at a time, thereby preventing simultaneous transmissions and reducing network congestion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the CCM interval is increased to handle more MEPs, then the network load and reception load are reduced, but CCM transmission bursts occur when all MEPs transmit simultaneously
Solution Approach 1:
The CCM transmission interval is segmented into multiple transmission windows, with each MEP assigned to a specific window. This divides the single transmission interval into N smaller intervals, where N is the number of MEPs, ensuring that MEPs transmit in distributed time slots rather than simultaneously, thus preventing bursts while maintaining the ability to handle large numbers of MEPs.
Solution Approach 2:
The transmission timing is made dynamic by assigning each MEP a unique transmission window based on its MEP ID. Instead of all MEPs using a fixed static interval, each MEP dynamically determines its transmission time within its assigned window, creating a distributed temporal pattern that avoids synchronization issues and simultaneous transmissions.
2Speed
If the CCM interval is increased to one minute, then the transmission frequency is reduced, but the burst problem still occurs and packet drops increase
Solution Approach 1:
The transmission interval is segmented into multiple transmission windows distributed across the MA. Even with a long interval like one minute, the segmentation ensures that MEPs transmit in distributed time slots rather than simultaneously, preventing bursts and packet drops while maintaining the reduced transmission frequency.
Solution Approach 2:
Each MEP transmits CCMs periodically within its assigned transmission window. This periodic action with distributed timing ensures that while the overall transmission frequency is low (e.g., once per minute), the transmissions are spread out in time rather than occurring as simultaneous bursts, preventing packet drops.
3Reliability
If all MEPs transmit CCMs simultaneously, then the continuity check coverage is maximized, but network queues are overwhelmed and packets are dropped
Solution Approach 1:
The simultaneous transmission is segmented into distributed time slots across multiple transmission windows. Each MEP transmits within its assigned window, maintaining continuity check coverage across all MEPs while distributing the traffic load over time, thus preventing network queue overflow and packet drops.
Solution Approach 2:
The transmission timing is made dynamic and distributed rather than static and simultaneous. Each MEP determines its transmission time based on its unique ID and assigned window, creating a dynamic temporal distribution that maintains comprehensive coverage while avoiding network congestion through staggered transmissions.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach ensures that CCMs are transmitted at unique intervals, reducing the likelihood of packet drops and network congestion, even in large maintenance associations, by coordinating the transmission times of MEPs, thus maintaining network stability and reliability.
Implementation Method 1
Each clock is synchronized using a network time protocol
Data Source
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AI summary
A system and method minimizes collisions between transmitted connectivity fault management (CFM) packets. Maintenance association endpoints are formed from a plurality of network switch elements to form a maintenance association. The clocks between each network switch element within the maintenance association are synchronized. A unique transmission window is assigned to each maintenance association endpoint as part of the maintenance association. A respective CFM packet is transmitted as a continuity check message (CCM) within the unique transmission window.