MPLS Loop Detection Using a Recorded Route Label Stack

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Solution Overview

Problem

Conventional loop detection techniques in Multiprotocol Label Switching (MPLS) networks are limited in detecting complex loop scenarios, such as transient and permanent loops, which cause bandwidth amplification and congestion due to inconsistent routing tables and router failures.

Innovation Solution

Implementing a Recorded Route Label Stack (RRLS) in packets to identify routers uniquely, enabling loop detection by checking for the presence of a router's label in the stack, and dropping packets if a loop is detected, with optional loop detection notifications for diagnosis and repair.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional loop detection techniques are used in MPLS networks, then simple loop scenarios can be detected, but complex loop scenarios (transient and permanent loops) cannot be effectively detected

Engineering Contradiction:
Improveloop detection capabilityVSAvoiddetection mechanism complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent implements a Recorded Route Label Stack (RRLS) where router labels are nested in a hierarchical structure within packet headers. Each router pushes its label onto the stack, creating a nested record of the traversal path. This nested structure enables detection of complex loop scenarios by allowing routers to examine the complete nested history of visited routers, rather than relying on simple detection mechanisms that only handle basic loop cases.

Inventive Principle:
Principle #7Nested doll (Nesting)

2Measurement precision

If router labels are pushed onto packets for loop detection, then loop detection precision is improved, but packet header overhead increases

Engineering Contradiction:
Improveloop detection precisionVSAvoidpacket header size
Core Design Contradiction:
Measurement precisionVSQuantity of substance

Solution Approach 1:

The patent applies partial action by implementing loop detection only on specific packet types or under certain network conditions rather than universally on all packets. The RRLS mechanism can be selectively activated based on network policies, packet priorities, or detected anomaly patterns, thereby reducing the overall packet header overhead while maintaining sufficient detection precision for critical loop scenarios.

Inventive Principle:
Principle #16Partial or excessive action

3Loss of energy

If packets are dropped upon loop detection, then bandwidth amplification is reduced, but network throughput decreases

Engineering Contradiction:
Improvebandwidth consumptionVSAvoidnetwork throughput
Core Design Contradiction:
Loss of energyVSProductivity

Solution Approach 1:

The patent implements feedback mechanisms where loop detection information is used to dynamically adjust network routing decisions. When loops are detected via the RRLS, the system provides feedback to routing protocols to modify path selections and prevent future loops. This feedback-driven approach reduces bandwidth amplification from loops while maintaining network throughput by avoiding repeated looped transmissions rather than indiscriminately dropping all packets.

Inventive Principle:
Principle #23Feedback

Data Source

PatentEP3869748B1Loop detection in multiprotocol label switching
Publication Date: 2025.12.10 NOKIA SOLUTIONS & NETWORKS OY
  • EP3869748B1 patent drawingFigure 1
  • EP3869748B1 patent drawingFigure 2
  • EP3869748B1 patent drawingFigure 3

AI summary

A router is configured for deployment in a network. The router includes a memory configured to store a first identifier that uniquely identifies the router in the network. The router also includes a processor configured to push the first identifier onto a first labeled data packet prior to transmission of the first labeled data packet. In response to detecting the first identifier in a second labeled data packet received from the network, the processor is configured to drop the second labeled data packet.