Probabilistic Congestion Indication Based on Packet Size
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Solution Overview
Problem
Existing congestion mitigation methods in communication networks fail to fairly share bandwidth among data flows with different packet sizes, leading to unfairness in bandwidth allocation.
Innovation Solution
A network device is configured with a normalization function that calculates a normalized probability for congestion indication based on the ratio of the packet size to a reference packet size, ensuring fair and accurate bandwidth sharing by randomly applying congestion indications, such as marking or dropping packets, using a lookup table or exponential function.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If congestion indication is applied uniformly to all packets regardless of size, then implementation is simple, but bandwidth sharing becomes unfair among different packet sizes
Solution Approach 1:
The patent applies different congestion indication probabilities to packets based on their local property (packet size). The normalization function adjusts the probability according to the ratio of packet size to reference size, ensuring that each packet size category receives appropriate treatment. This resolves the contradiction by making the system simple to implement through a standardized function while achieving fairness through size-aware probability adjustment.
Solution Approach 2:
The patent changes the probability parameter dynamically based on packet size. By introducing a normalization function that computes probability as a function of packet size ratio, the system transitions from a fixed uniform probability to a variable probability that adapts to different packet sizes. This resolves the contradiction by maintaining implementation simplicity through a mathematical function while achieving fairness through parameter adaptation.
2Reliability
If congestion indication probability is adjusted based on packet size, then bandwidth sharing fairness improves, but computational complexity increases
Solution Approach 1:
The patent uses a lookup table that stores pre-computed normalization values for different packet size ratios. Instead of performing complex real-time calculations, the system copies the appropriate probability value from the table based on the packet size. This resolves the contradiction by maintaining fairness through size-based probability adjustment while reducing computational complexity through pre-computation and table lookup.
3Ease of operation
If small packets are treated with the same congestion probability as large packets, then processing is uniform, but small packets experience excessive congestion indication
Solution Approach 1:
The patent changes the congestion indication probability parameter based on packet size. For small packets (size ratio < 1), the normalization function produces a lower probability, reducing excessive congestion indication. For large packets (size ratio > 1), it produces a higher probability. This resolves the contradiction by maintaining processing uniformity through a standardized function while achieving accuracy through size-proportional probability adjustment.
Data Source
AI summary
A network device includes circuitry and multiple ports. The circuitry is configured to hold a definition of a normalization function that determines, based on (i) a reference probability of applying a congestion indication operation to packets having a predefined reference packet-size and (ii) a packet-size parameter, a normalized probability of applying the congestion indication operation to packets whose size equals the packet-size parameter. The normalization function depends exponentially on a ratio between the packet-size parameter and the reference packet-size. The circuitry id configured to store packets in a queue, and to schedule transmission of at least some of the queued packets via an output port, to calculate the normalized probability for a given packet, by applying the normalization function to an actual reference probability and an actual size of the given packet, and randomly apply a congestion indication operation to the given packet, in accordance with the normalized probability.