Packet Network Admission Control via Value-Cost Comparison
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Solution Overview
Problem
Existing admission control methods in packet networks, such as pre-congestion notification (PCN), fail to consider the actual path congestion levels, leading to unnecessary rejection of data flows despite available capacity on other paths, due to reliance on fixed thresholds and lack of integrated path routing decisions.
Innovation Solution
Implementing a method where session values are assigned based on their importance, compared to path congestion costs, allowing for dynamic admission control and path selection that prioritizes high-value sessions over low-value ones, and optimizes path usage by calculating congestion measures like exponentially weighted moving averages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If pre-congestion notification (PCN) is used for admission control, then congestion level measurement is improved, but path routing information is lost leading to unnecessary flow rejections
Solution Approach 1:
The patent segments the admission control process into two independent components: path selection (using ECN-marked packets to measure congestion on each path) and admission decision (comparing session value to path congestion costs). This allows each component to optimize its function independently, resolving the contradiction between measurement precision and routing adaptability.
Solution Approach 2:
The patent adds a new dimension to admission control by introducing session value as a separate parameter from congestion measurement. Instead of relying solely on congestion thresholds, the system now operates in a two-dimensional space of (session value, path congestion cost), enabling flows to be admitted based on their value even when paths show some congestion, thereby improving adaptability without sacrificing measurement precision.
2Ease of manufacture
If fixed congestion thresholds are used for admission control, then implementation simplicity is improved, but flow admission accuracy deteriorates causing unnecessary rejections
Solution Approach 1:
The patent replaces static fixed thresholds with dynamic session-specific values. Each flow type is assigned a value that reflects its importance to the network operator, and admission decisions are made dynamically by comparing this value against real-time path congestion costs. This maintains implementation simplicity through standardized valuation while dramatically improving admission accuracy.
Solution Approach 2:
The patent changes the fundamental parameter used for admission control from binary threshold comparison to continuous value-cost comparison. Instead of asking 'is congestion below threshold?', the system asks 'is session value greater than path congestion cost?', allowing for nuanced admission decisions that accurately reflect both network conditions and service priorities.
3Quantity of substance
If congestion measurement aggregates all paths, then overall congestion assessment is improved, but individual path capacity information is lost
Solution Approach 1:
The patent segments congestion measurement by path, maintaining separate congestion cost values for each available path rather than aggregating them. ECN-marked packets are tracked individually per path, and admission control evaluates each path's congestion independently. This preserves complete path capacity information while still providing comprehensive overall congestion assessment.
Solution Approach 2:
The patent performs congestion measurement on all paths (excessive action) rather than selecting a single representative path. By measuring and maintaining congestion information for every available path, the system ensures that no path capacity information is lost, enabling optimal path selection and admission decisions even when network topology changes occur.
Data Source
AI summary
In embodiments of the invention when a session request is received the value assigned to that session is compared to present congestion costs in the network at the present time. If the value of the session exceeds the cost then the session is accepted; otherwise it is rejected. It is possible to show mathematically that, provided this strategy is used for all session requests, then, when demand exceeds supply for a given resource, the congestion measurement for that resource rises to become equal to its shadow price. Here, in a model of a capacity constrained network, the shadow price of a capacity constraint is the cost to other users of using one unit of capacity. Congestion measurements can therefore be used to provide a “cost” (to other users) of admitting the flow to the network, which can then be compared against the “value” (to the network operator) of admitting the flow during the admission control evaluation. Additionally, this “cost” vs. “value” comparison can be used for path selection, as well as any other resource management decision. For example, in particularly preferred embodiments a session is not only admitted based upon the cost value comparison, but is also assigned to a particular path which maximizes value minus cost.