Stateful Service Function Path Redundancy via Segment Routing

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Solution Overview

Problem

Current solutions do not effectively provide service function path protection that supports stateful processing, leading to potential communication failures and disruptions in packet flows when a service function path fails.

Innovation Solution

Implementing a method that utilizes multiple instances of a replicated service function path with synchronized stateful service functions to redirect packets to a backup instance upon failure, ensuring continuous processing and minimizing disruption by using segment routing extensions to steer packets to primary or backup service functions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If service function path protection is implemented using current solutions, then path redundancy is provided, but stateful processing is not supported leading to communication failures

Engineering Contradiction:

Improveservice function path availabilityVSAvoidstateful processing support

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The service function path is segmented into multiple instances (primary and backup), allowing independent operation of each instance. This segmentation enables the system to switch between instances while maintaining stateful processing, as each instance can independently handle state synchronization for packet flows.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system changes the operational parameters of service function instances by implementing state synchronization mechanisms. When switching from primary to backup instance, the backup instance receives and processes state information for affected packet flows, allowing it to maintain stateful processing capabilities despite being a standby instance.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If redundant service function instances are created, then path protection is provided, but system complexity increases

Engineering Contradiction:

Improveservice function path availabilityVSAvoidsystem architecture complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

Backup service function instances serve multiple purposes: they act as standby for path protection and simultaneously maintain state synchronization for affected packet flows. This multi-functionality reduces overall system complexity by eliminating the need for separate state management mechanisms.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The system performs preliminary state synchronization with backup instances before failures occur. By pre-synchronizing state information, the system avoids complex real-time state management during failure scenarios, simplifying the overall architecture.

Inventive Principle:

Principle #10Preliminary action

3Reliability

If state synchronization is implemented across replicated instances, then stateful processing is maintained, but communication overhead increases

Engineering Contradiction:

Improvestateful processing continuityVSAvoidcommunication overhead

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The system implements partial state synchronization by only synchronizing state information for affected packet flows rather than all packet flows. This selective approach maintains stateful processing continuity while minimizing communication overhead between primary and backup instances.

Inventive Principle:

Principle #16Partial or excessive action

Data Source

PatentUS11677614B2Method and apparatus for protecting stateful service function paths

Publication Date: 2023.06.13 HUAWEI TECH CO LTD

AI summary

A method, apparatus and system for providing stateful service function paths with redundancy are provided. Multiple instances of a service function path are included, each with at least one instance of a stateful service function. The redundant stateful service functions transmit messages between one another to so that the current state is synchronized. Upon failure of a service function in a first instance of the service function path, packets are redirected to a backup associated with the failed service function located in another instance of the service function path. Once processed by the backup service function, the redirected packets may be routed back to the first instance of the service function path.