Credit-Based Bandwidth Allocation for RPR Starvation
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Solution Overview
Problem
Resilient Packet Ring (RPR) networks experience starvation issues due to oversubscription and prioritization, where some stations lack access to network resources despite fairness mechanisms increasing complexity and not fully addressing the problem unless bandwidth is pre-allocated.
Innovation Solution
A method and apparatus that allocate and reserve bandwidth for each station by using 'dummy' or 'tax' packets to ensure every station has transmission opportunities, eliminating starvation by guaranteeing bandwidth through a table-based system that determines and allocates transmit opportunities and reserved bandwidth based on credit bandwidth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fairness mechanisms are implemented to ensure each station has network access, then network fairness is improved, but system complexity increases
Solution Approach 1:
The patent implements a self-service mechanism where stations automatically allocate bandwidth to themselves and downstream stations using a credit-based system. Each station maintains a credit counter that is incremented when it receives packets and decremented when it transmits. This automatic self-allocation eliminates the need for complex centralized fairness control mechanisms, thereby improving network fairness while keeping system complexity low.
Solution Approach 2:
The patent uses a pre-allocation mechanism where each station is pre-assigned a credit bandwidth value that represents its guaranteed share of network resources. This preliminary assignment of bandwidth credits occurs before actual data transmission, ensuring that every station has a predetermined fair share of bandwidth available, which simplifies runtime fairness management.
2Productivity
If spatial reuse is enabled to increase bandwidth utilization, then network capacity is improved, but station starvation occurs
Solution Approach 1:
The patent applies local quality by allowing different stations to have different credit bandwidth allocations based on their specific needs and positions in the network. Each station's credit counter is locally maintained and managed, allowing flexible local bandwidth allocation that adapts to spatial reuse patterns while ensuring every station maintains fair access to network resources.
3Reliability
If bandwidth is pre-allocated to eliminate starvation, then station access fairness is improved, but network flexibility decreases
Solution Approach 1:
The patent implements a dynamic bandwidth allocation system where credit bandwidth values are not fixed but can be adjusted based on network conditions and station performance. The credit counters are dynamically updated during operation, allowing the network to adapt to changing traffic patterns and station requirements while maintaining fair access for all stations. This dynamic approach combines the fairness benefits of pre-allocation with the flexibility of runtime adjustment.
Data Source
AI summary
A method and apparatus for minimizing starvation of a station in a ring networked environment includes allocating a tax to each of the stations in the ring, and, for each packet that is to be transited though the ring, providing bandwidth to the station in the form of a tax packet, which allows the station to have ring access.