Entropy Prefix Segment Identifier for Segment Routing Networks

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Solution Overview

Problem

In segment routing networks, the use of entropy labels increases the label stack size due to the need for an entropy label indicator (ELI) and multiple POP operations, which complicates load balancing and efficiency.

Innovation Solution

The introduction of an Entropy Prefix Segment Identifier (EP-SID) combines label forwarding and entropy label identifier functions, eliminating the need for ELI and reducing the label stack size by allowing the entropy label to be positioned beneath the prefix segment identifier.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If entropy label is used in MPLS to improve load balancing, then load balancing capability is improved, but label stack size increases due to the need for entropy label indicator and multiple POP operations

Engineering Contradiction:

Improveload balancing capabilityVSAvoidlabel stack size

Core Design Contradiction:

Adaptability or versatilityVSQuantity of substance

Solution Approach 1:

The patent combines the entropy label indicator and entropy label into a unified structure where the entropy label is embedded within the prefix segment identifier. This merging eliminates the need for separate ELI and multiple POP operations, reducing label stack size while maintaining load balancing capability through the integrated entropy information in the prefix SID.

Inventive Principle:

Principle #5Merging (Combining)

2Adaptability or versatility

If entropy label indicator and multiple POP operations are used, then entropy label functionality is achieved, but device complexity increases

Engineering Contradiction:

Improveentropy label functionalityVSAvoiddevice complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent extracts the entropy label indicator functionality from being a separate operational step and integrates it directly into the prefix segment identifier structure. This extraction eliminates the need for separate ELI processing and multiple POP operations at transit nodes, reducing device complexity while preserving entropy label functionality through the consolidated prefix SID approach.

Inventive Principle:

Principle #2Taking out (Extraction)

3Loss of information

If separate entropy label indicator and entropy label are used, then entropy information is preserved, but label stack size increases

Engineering Contradiction:

Improveentropy information preservationVSAvoidlabel stack size

Core Design Contradiction:

Loss of informationVSQuantity of substance

Solution Approach 1:

The patent implements nesting by embedding the entropy label within the prefix segment identifier structure. The entropy information is nested inside the prefix SID, allowing entropy information to be preserved while eliminating the need for separate ELI and reducing overall label stack size. The nested structure enables single POP operations while maintaining all necessary entropy information for load balancing.

Inventive Principle:

Principle #7Nested doll (Nesting)

Data Source

PatentUS10237175B2Entropy prefix segment identifier for use with entropy label in segment routing networks

Publication Date: 2019.03.19 CISCO TECHNOLOGY INC

AI summary

In one embodiment, a method includes receiving at an ingress node in a segment routing network, an entropy prefix segment identifier, generating a label stack comprising the entropy prefix segment identifier and an entropy label beneath the entropy prefix segment identifier, and transmitting a packet comprising the label stack using the entropy prefix segment identifier as a transport label and an entropy label identifier. An apparatus and logic are also disclosed herein.