Packet Shaper for Cut-Through Switching in Mismatched Networks

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Solution Overview

Problem

In computationally-intensive applications, packet switching latency is exacerbated by port-speed mismatches in distributed networks, leading to buffer overflow in cut-through switching, which necessitates the use of store-and-forward switching, resulting in higher latency.

Innovation Solution

Implementing a packet shaper to pace data packets and match the ingress and egress data rates, allowing for cut-through switching in port-speed-mismatched environments by dynamically adjusting the transmission rate through a packet shaper, which can be implemented in hardware, software, or firmware, ensuring that data packets are forwarded efficiently without overflowing the cut-through buffer.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If cut-through switching is used to reduce latency, then packet transmission speed is improved, but buffer overflow occurs in port-speed-mismatched environments

Engineering Contradiction:

Improvepacket transmission speedVSAvoidbuffer overflow prevention

Core Design Contradiction:

SpeedVSReliability

Solution Approach 1:

A packet shaper is introduced as an intermediary component between the ingress and egress ports. The packet shaper receives packets from the ingress port, pace them according to the egress port's capabilities, and forward them to the egress port. This mediator ensures that the packet transmission rate is matched between both ports, preventing buffer overflow while maintaining cut-through switching performance.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If store-and-forward switching is used to prevent buffer overflow, then reliability is improved, but packet latency increases

Engineering Contradiction:

Improvebuffer overflow preventionVSAvoidpacket latency

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The system dynamically adjusts the packet transmission rate based on the capabilities of the egress port. The packet shaper continuously monitors and adapts the pacing of packets to match the egress port's transmission rate, allowing the system to maintain cut-through switching (low latency) while preventing buffer overflow through dynamic rate matching rather than static store-and-forward processing.

Inventive Principle:

Principle #15Dynamics

3Adaptability or versatility

If packet shaper is implemented to pace data packets, then port-speed mismatch is resolved, but device complexity increases

Engineering Contradiction:

Improveport-speed mismatch resolutionVSAvoidpacket shaper implementation

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The packet shaper operates by changing the timing parameter of packet transmission. Instead of modifying packet content or structure, the packet shaper adjusts the inter-arrival time between packets to match the egress port's capabilities. This parameter-based approach (changing transmission rate/timing) resolves port-speed mismatches without requiring complex packet manipulation or multiple hardware components.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS9065755B2Low-latency switching

Publication Date: 2015.06.23 AVAGO TECHNOLOGIES INTERNATIONAL SALES PTE LTD

AI summary

Disclosed are systems and methods for cut-through switching in port-speed-mismatched networks. Specifically, systems and methods are described in which data packets from an ingress device are paced, thereby matching the data rate of the ingress device with the data rate of the egress device.