Link Aggregation Loop Prevention in Customer Premises Equipment

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Solution Overview

Problem

Link aggregation in residential gateways can create loops when both customer premises equipment (CPEs) implement this technology, leading to latency and packet losses due to unnecessary Wi-Fi load and IP fragmentation caused by additional headers in existing protocols like MPTCP and GRE.

Innovation Solution

A method for routing data that detects whether the data has already undergone link aggregation in the upstream network equipment, allowing the second network equipment to select an appropriate output link to avoid loops by using the same aggregation rules, ensuring data is transmitted over a link that has not already been aggregated, thereby preventing loop formation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If link aggregation is implemented in both CPEs to increase bandwidth and redundancy, then network throughput and reliability are improved, but loops are formed causing latency and packet losses

Engineering Contradiction:

Improvenetwork throughputVSAvoidpacket delivery reliability

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent applies preliminary action by detecting aggregation markers in incoming packets before routing decisions are made. The second CPE checks whether the received packet already carries an aggregation marker from the first CPE, and proactively prevents loop formation by not forwarding it back through the aggregated link, thus avoiding latency and packet loss before they occur

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent introduces an intermediary mechanism in the form of aggregation markers (such as TCP options or GRE protocol identifiers) that act as mediators between the two CPEs. These markers enable the second CPE to recognize packets that have already undergone aggregation at the first CPE, allowing intelligent routing decisions that prevent loops while maintaining the benefits of link aggregation

Inventive Principle:

Principle #24Intermediary (Mediator)

2Adaptability or versatility

If existing protocols like MPTCP and GRE are used for link aggregation, then multipath connectivity is achieved, but additional headers cause IP fragmentation and decrease MTU

Engineering Contradiction:

Improvemultipath connectivityVSAvoidMTU size

Core Design Contradiction:

Adaptability or versatilityVSQuantity of substance

Solution Approach 1:

The patent extracts only the essential aggregation identification function from complex protocols like MPTCP and GRE. Instead of using their full header structures, it extracts and uses only the necessary marker fields (such as TCP options or GRE protocol identifiers) to detect aggregation status, thereby maintaining multipath connectivity while minimizing additional overhead and preserving larger MTU sizes

Inventive Principle:

Principle #2Taking out (Extraction)

Data Source

PatentUS11570087B2Data routing in a customer-premises equipment using link aggregation

Publication Date: 2023.01.31 SAGEMCOM BROADBAND SAS

AI summary

The routing of data received from a first network device into a second network device, each having a link aggregation engine, includes detecting whether or not the data has already undergone a link aggregation operation in the first device or upstream, based on markers present in the data, and then selecting an output link from all the output links of the second device participating in link aggregation if the data has not already undergone link aggregation, or selecting the output link from all the output links of the second device participating in link aggregation except for the output link towards the first device if the data has already undergone link aggregation, and transmitting the data on the output link selected.