2-Fiber Shared Protection Ring Bandwidth Utilization
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Solution Overview
Problem
Current 2-fiber shared protection ring systems in SDH/SONET networks cannot implement shared protection and extra traffic on STM-1/OC-3 interfaces due to the requirement for an even number of AU4s/AU3s/STS-1s, limiting bandwidth utilization and extra traffic capacity in ring topologies.
Innovation Solution
Configuring the 2-fiber shared protection ring with predetermined granularities such as VC12, VC11, VC3, and VC12-VC3 for AU4 mapping, and VC12, VC11, and VC3 for AU3 mapping, to allocate specific time slots as work or protect channels, enabling efficient bandwidth sharing and extra traffic carrying capabilities on STM-1/OC-3 interfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If 2-fiber shared protection ring is implemented on STM-1/OC-3 interfaces, then bandwidth utilization and extra traffic capacity are improved, but the system cannot be implemented due to the requirement for an even number of AU4s/AU3s/STS-1s
Solution Approach 1:
The patent segments the STM-1/OC-3 interface bandwidth into smaller granularities (VC12, VC11, VC3, VC12-VC3 for AU4 mapping; VC12, VC11, VC3 for AU3 mapping) instead of requiring even division at the AU4/AU3/STS-1 level. This segmentation allows flexible allocation of time slots as work or protect channels, enabling 2-fiber shared protection ring implementation on interfaces with odd numbers of basic units by configuring appropriate granularity combinations that sum to the total available capacity.
Solution Approach 2:
The patent changes the parameter of protection channel allocation from fixed even division at AU4/AU3/STS-1 level to flexible allocation at finer VC granularity levels. By changing the allocation parameter from coarse-grained (AU4/AU3/STS-1) to fine-grained (VC12/VC11/VC3), the system can accommodate interfaces with odd numbers of basic units while maintaining the 2-fiber shared protection ring functionality and enabling extra traffic capacity.
2Productivity
If protect capacity is shared among N network elements, then extra traffic capacity is improved, but the complexity of managing shared protection increases
Solution Approach 1:
The patent applies preliminary action by pre-configuring the granularity allocation (VC12, VC11, VC3, VC12-VC3 for AU4 mapping; VC12, VC11, VC3 for AU3 mapping) and establishing work-protect channel mappings before failures occur. The system pre-allocates specific time slots as work channels and others as protect channels, and pre-configures the mapping relationships between them. This preliminary configuration simplifies real-time failure response by eliminating the need for complex dynamic calculations during protection switching events.
Solution Approach 2:
The patent implements self-service through automatic detection and switching mechanisms that enable the protection ring to manage its own shared protect capacity without external intervention. When a failure occurs, the system automatically detects it, identifies the affected work channels, and switches them to use the shared protect capacity of neighboring links. The K-Byte protocol carries failure detection information automatically around the ring, enabling self-managed protection switching that reduces operational complexity despite the shared nature of the protect capacity.
Data Source
AI summary
A method for protection of data traffic transmitted over 2-fiber shared protection ring on STM-1/OC-3 interface is provided. Also, the method involves carrying extra traffic in a ring topology for STM-1/OC-3 interface. This is achieved by fixing the granularity to one of ‘VC12/VC11/VC3/VC12-VC3/VC11-VC3’ for the STM-1 interface and to one of ‘VT2/VT1.5/STS-1’ for the OC-3 interface upfront when the protection is configured on the network element.