DCAM Sparing via Local State Segmentation
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Solution Overview
Problem
The existing self-healing architecture for CCAP devices in broadband networks experiences signal attenuation and increased costs due to the need for high-powered amplifiers and extensive memory storage for state information, leading to reduced signal-to-noise ratio and longer switch-over times during sparing events.
Innovation Solution
Implementing a sparing approach where each DCAM card stores state information for only its adjacent active card and switches operations within a single hop of the daisy chain, reducing signal propagation distance and memory requirements, and allowing for instant switch-over by pre-loading standby registers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single spare DCAM card is used to back up multiple active DCAM cards, then device complexity is reduced, but signal attenuation and cross-talk increase due to long daisy chain propagation
Solution Approach 1:
The system divides the sparing function into multiple segments, where each active DCAM card maintains state information for its adjacent spare card. This segmentation reduces the daisy chain propagation distance for each sparing operation, thereby minimizing signal attenuation and cross-talk while maintaining manageable device complexity.
Solution Approach 2:
Each DCAM card is configured with local state information specifically for its adjacent spare card, rather than requiring one spare card to hold state information for all active cards. This local quality approach reduces the propagation distance and signal degradation while maintaining the sparing functionality.
2Reliability
If high-powered amplifiers are used to compensate for signal attenuation, then signal quality is maintained, but board power consumption and thermal issues increase
Solution Approach 1:
The system pre-loads standby registers with state information for adjacent DCAM cards before a failure occurs. This preliminary action enables instant switch-over without requiring high-powered amplifiers to maintain signal quality during transition, thereby reducing power consumption and thermal issues while maintaining reliability.
3Reliability
If extensive memory storage is used to store state information for multiple cards, then sparing capability is improved, but manufacturing and operational costs increase
Solution Approach 1:
Each DCAM card stores state information locally for only its adjacent spare card, rather than requiring extensive memory to store state information for multiple cards. This local quality approach reduces memory requirements and manufacturing costs while maintaining adequate sparing capability through distributed state information across multiple cards.
Data Source
AI summary
A device and method for routing separate data flows to subscribers on a content distribution network are provided. The device includes a group of access modules having signal processing circuitry each coupled to a corresponding interface unit. The interface units are coupled in a daisy chain configuration. The access modules include at least first and second active access modules and a spare access module. The group being configured for normal mode operation in which the first active access module processes a first data flow and the second active access module processes a second data flow, and the group being configured for sparing event mode operation in which the first data flow is automatically switched to the second active access module and the second data flow is automatically switched to the spare access module.