MPLS TTL Loop Suppression in Layer-2 Transit Networks

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing layer-two transit networks lack effective loop suppression mechanisms without additional hardware or packet headers, which can lead to infinite unicast or multicast loops.

Innovation Solution

Incorporating a time-to-live (TTL) attribute within the MPLS label field of packets, allowing provider routers to detect and manage loops through recalculation and packet dropping, thereby eliminating the need for additional hardware or packet headers.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If loop suppression mechanisms are implemented in layer-two transit networks, then network reliability is improved, but device complexity increases due to additional hardware or packet headers

Engineering Contradiction:

Improveloop suppression capabilityVSAvoidhardware or packet header additions

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges the loop suppression function with the existing MPLS label field by utilizing the TTL attribute already present in MPLS packets. This combination allows layer-two networks with MPLS encapsulation to achieve loop suppression without adding separate hardware mechanisms or modifying packet structures, thereby improving reliability while avoiding increased device complexity

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The invention enables the network to self-regulate loops by having provider routers automatically evaluate the TTL attribute in MPLS packets and drop packets that indicate loop conditions. This self-service approach eliminates the need for external loop suppression hardware or additional packet headers, as the existing MPLS infrastructure performs the loop detection and suppression functions

Inventive Principle:

Principle #25Self-service

2Difficulty of detecting and measuring

If additional hardware or packet headers are added for loop suppression, then loop detection capability is improved, but resource usage increases

Engineering Contradiction:

Improveloop detection capabilityVSAvoidhardware or packet header resources

Core Design Contradiction:

Difficulty of detecting and measuringVSQuantity of substance

Solution Approach 1:

The patent makes the existing MPLS TTL attribute serve multiple functions: it continues to perform its traditional time-to-live function for packet expiration while simultaneously serving as a loop detection mechanism. This multi-functionality improves loop detection capability without requiring additional packet headers or hardware resources

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The MPLS encapsulation acts as an intermediary that bridges layer-two and layer-three functionalities. By utilizing the layer-three MPLS TTL attribute for layer-two loop suppression, the invention avoids the need for separate loop detection mechanisms, thereby improving detection capability without increasing hardware or packet header resources

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS9900246B2System and method for loop suppression in transit networks

Publication Date: 2018.02.20 HUAWEI TECH CO LTD

AI summary

An embodiment method of loop suppression in a layer-two transit network with multiprotocol label switching (MPLS) encapsulation includes receiving a packet at a provider edge (PE) router for the layer-two transit network. The packet is stored in a non-transitory memory on the PE router. The packet is stored according to a packet data structure having an MPLS label field and a layer-two header. A time-to-live (TTL) attribute is then determined for the packet. The TTL attribute is written to the non-transitory memory in the MPLS label field. The packet is then routed according to information in the layer-two header.