Loop-back Packet Mechanism for Border Relay Device Capability Detection

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Solution Overview

Problem

Existing methods for determining the operational capabilities of border relay devices in computer networks, such as reachability and functionality, often rely on the control path which incurs higher latency compared to the forwarding path, leading to inefficiencies and potential malfunctions, especially when handling multiple ICMP messages simultaneously.

Innovation Solution

The technique involves using a loop-back packet mechanism where a host device generates an IPv4 loop-back packet encapsulated in an IPv6 packet, which is processed through the forwarding path of the border relay device, allowing for the determination of operational characteristics like reachability and MTU size without significant CPU overhead, leveraging the faster forwarding path for low-latency operations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the control path (CPU) is used to determine operational capabilities of the border relay device, then the determination can be performed with full processing capability, but the latency increases and CPU overhead increases

Engineering Contradiction:

Improveoperational capability determination accuracyVSAvoiddetermination latency

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The patent segments the border relay device into two distinct processing paths: a control path using the CPU for complex operations, and a forwarding path using dedicated hardware circuitry for packet forwarding operations. By segmenting the operational capability determination to use only the forwarding path, the patent achieves low-latency determination without burdening the CPU, thus resolving the contradiction between measurement accuracy and time loss.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces a loopback packet as an intermediary mechanism that enables operational capability determination through the forwarding path. The loopback packet acts as a mediator that carries test data through the forwarding path's encapsulation and decapsulation processes, allowing the host device to assess border relay device capabilities without direct CPU involvement, thereby reducing latency while maintaining determination accuracy.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Adaptability or versatility

If the control path (CPU) is used to process multiple ICMP messages simultaneously, then comprehensive processing is achieved, but the CPU may become overloaded causing malfunctions

Engineering Contradiction:

ImproveICMP message processing capabilityVSAvoiddevice malfunction risk

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent segments the processing workload by assigning ICMP message handling to the forwarding path's hardware circuitry rather than the CPU. This segmentation allows multiple ICMP messages to be processed simultaneously through the forwarding path without overloading the CPU, maintaining versatility while improving reliability by preventing CPU-induced malfunctions.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The forwarding path's hardware circuitry performs self-service by autonomously handling encapsulation, decapsulation, and loopback packet processing without requiring CPU intervention. This self-service capability enables the border relay device to process multiple ICMP messages concurrently through hardware acceleration, ensuring both high adaptability and system reliability.

Inventive Principle:

Principle #25Self-service

3Productivity

If the forwarding path is used for operational capability determination, then latency is reduced and CPU overhead is minimized, but the determination must rely on forwarding path capabilities only

Engineering Contradiction:

Improvedetermination speedVSAvoiddetermination capability scope

Core Design Contradiction:

ProductivityVSAdaptability or versatility

Solution Approach 1:

The patent leverages the multi-functionality of the forwarding path by designing the loopback packet mechanism to assess multiple operational capabilities (reachability, MTU size, fragmentation capability) through a single unified process. The forwarding path's encapsulation and decapsulation functions are universally applied to various test scenarios, enabling comprehensive capability determination at high speed without requiring CPU involvement, thus achieving both productivity and adaptability.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS10819617B1Loop-back packet for determining operational capabilities of border relay device

Publication Date: 2020.10.27 JUNIPER NETWORKS INC

AI summary

This disclosure describes techniques to generate information of the operational characteristics of a border relay device. For example, a host device transmits a loop-back packet that travels through a forwarding path of the border relay device, rather than a control path, and back to the host device. Based on the host device receiving the loop-back packet, the host device may generate information indicative of operational characteristics of the border relay device.