Credit-Based Flow Control for IP Router Buffer Management

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Solution Overview

Problem

Existing aggregate control methods for traffic flow in communication networks are not effectively applicable to connectionless networks, such as those using Internet Protocol (IP), due to their different nature.

Innovation Solution

A switching device with input and output ports, and a method to regulate data packet transfer based on a count of packets previously transferred, ensuring loss-free transfer by providing information to sending devices about buffer availability through a credit-based system, and controlling packet transmission to prevent buffer overflow.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If aggregate control methods are applied in connectionless networks, then traffic flow control is implemented, but the methods are not effectively applicable due to the different nature of connectionless networks

Engineering Contradiction:

Improveapplicability of aggregate control methodsVSAvoideffectiveness of traffic control

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent transforms the control approach by changing the fundamental parameters of how traffic control is implemented in connectionless networks. Instead of using traditional aggregate control methods designed for connection-oriented networks, the invention introduces credit-based flow control mechanisms and buffer status reporting that adapt to the stateless nature of IP networks, making aggregate control effective in connectionless environments.

Inventive Principle:

Principle #35Parameter changes

2Productivity

If data packets are transmitted without control, then network throughput is maximized, but buffer overflow occurs causing data loss

Engineering Contradiction:

Improvenetwork throughputVSAvoiddata packet loss

Core Design Contradiction:

ProductivityVSLoss of substance

Solution Approach 1:

The patent implements preliminary action by having switching devices proactively report buffer status and credit information to sending devices before buffers overflow. This advance notification allows sending devices to regulate their transmission rates preemptively, preventing data loss while maintaining maximum throughput by utilizing available buffer capacity.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The invention establishes a feedback mechanism where switching devices continuously monitor input buffer status and send credit information back to sending devices. This feedback loop enables dynamic adjustment of transmission rates based on real-time buffer conditions, preventing overflow while maximizing network throughput through intelligent flow control.

Inventive Principle:

Principle #23Feedback

3Reliability

If traffic is throttled to prevent congestion, then data loss is prevented, but network utilization decreases

Engineering Contradiction:

Improvelossless transferVSAvoidnetwork utilization

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent applies dynamics by implementing adaptive flow control that continuously adjusts transmission rates based on real-time buffer status. Rather than static throttling, the system dynamically regulates traffic flow to match available capacity, preventing data loss while maximizing network utilization through flexible, condition-based rate adjustment.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The invention changes the control parameter from binary throttling (on/off) to continuous rate adjustment based on credit values and buffer status. This parameter change enables fine-grained control of traffic flow, maintaining lossless transfer while optimizing network utilization by transmitting at the highest safe rate at any given moment.

Inventive Principle:

Principle #35Parameter changes

4Loss of substance

If buffer capacity is increased to handle congestion, then data loss is reduced, but device complexity and memory requirements increase

Engineering Contradiction:

Improvedata packet lossVSAvoidbuffer management complexity

Core Design Contradiction:

Loss of substanceVSDevice complexity

Solution Approach 1:

The patent introduces credit-based flow control as an intermediary mechanism between sending devices and buffer management. Instead of directly increasing buffer capacity, the system uses credit tokens to mediate transmission rights, allowing buffers to remain smaller while preventing data loss through intelligent access control and flow regulation.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS8130652B2Control of data in communication networks

Publication Date: 2012.03.06 COMPLEX SYST RES

AI summary

A router (14) for use in a communication network (10) and an associated method. The router (14) includes input ports each having an associated input buffer for receiving data packets from a sending device and output ports for sending data packets to a receiving device. The router (14) also includes a means to direct data packets from the or each input port to one or more of the output ports and a means for providing information to each sending device such that a determination may be made as to whether or not the sending device may transmit packets in order to assure lossless transfer. The means to direct data packets from a particular input port includes a method of control in order to regulate the transfer of data packets, where this regulation is based on a count of the data packets previously transferred from that input port and not yet output from the output port. The router (14) transmits data packets from the output port only when loss free transfer to the input port of the receiving router (14) is assured.