Software LCAS Emulation for SONET VCG Capacity Control
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Solution Overview
Problem
Existing SONET networks face challenges in managing link capacity efficiently, particularly in high-speed networks, as hardware support for the Link Capacity Adjustment Scheme (LCAS) protocol is often limited, leading to costly hardware replacements and incomplete LCAS support for vendors providing both low-speed and high-speed networks.
Innovation Solution
The implementation of a software-based emulation of the LCAS protocol using a hardware poller facility with VCG state machines and member state machines to manage the status and state of virtual concatenation groups, allowing for dynamic adjustment of bandwidth by monitoring and responding to SONET defects and H4 byte corruption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If hardware support for LCAS protocol is implemented, then link capacity adjustment capability is improved, but device complexity and cost increase
Solution Approach 1:
The patent replaces hardware-based LCAS protocol implementation with a software-based implementation. The line card controller executes software modules that emulate LCAS functionality, including generating LCAS control words, processing LCAS messages, and managing virtual concatenation groups. This substitution eliminates the need for specialized hardware circuits while maintaining full LCAS capability, thereby reducing device complexity and cost without sacrificing adaptability.
2Adaptability or versatility
If hardware replacement is performed to support LCAS, then LCAS feature support is improved, but loss of time and cost increase
Solution Approach 1:
The patent implements LCAS functionality through software that is pre-configured and loaded into the existing line card controller's memory. The controller is already equipped with the necessary processing capabilities, and the LCAS software modules are ready to execute immediately upon activation. This eliminates the time-consuming hardware replacement process entirely, as the existing hardware can be upgraded to support LCAS simply by loading and activating the appropriate software, thus avoiding network downtime and replacement costs.
3Speed
If LCAS is implemented at hardware level, then protocol processing speed is improved, but ease of manufacture and deployment worsen
Solution Approach 1:
The patent designs the line card controller as a universal platform capable of executing multiple functions through software modules. The same controller hardware that performs standard SONET/SDH routing and switching functions also executes LCAS protocol processing when the appropriate software is loaded. This multi-functional approach allows a single hardware design to serve multiple purposes, simplifying manufacturing and deployment while maintaining adequate protocol processing speed through efficient software implementation on the existing controller.
Data Source
AI summary
A technique controls the capacity of a virtual concatenation group (VCG) carried on a SONET path of a data network. Efficient control of VCG capacity is provided by emulating aspects of a Link Capacity Adjustment Scheme (LCAS) protocol in software. A hardware poller facility is employed to manage the status and state of the VCG, as well as members belonging to the VCG. The hardware poller contains one or more VCG state machines (VSMs) and member state machines (MSMs) configured to maintain the status and states of the VCGs and their members.