Hitless Failover via Dedicated Database Card

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Solution Overview

Problem

Network elements face challenges in maintaining continuous operation without interruptions when a master control card fails, due to the complexity of synchronizing database states and resource constraints during hitless failover processes.

Innovation Solution

Implementing a network element with a master control card, a backup control card, and a separate database card that stores control plane processing information, allowing the backup control card to take over and retrieve protocol state information from the database card in case of the master's failure, thereby ensuring hitless failover without resetting the database.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a backup control card is implemented to take over control plane processing, then reliability is improved, but device complexity increases due to the need to synchronize database states between master and backup cards

Engineering Contradiction:

ImproveavailabilityVSAvoidsynchronization complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent segments the control plane processing functions by separating the database card from the control cards. The database card independently stores and maintains protocol state information, while control cards only access this information through standardized interfaces. This segmentation eliminates the complex synchronization requirement between master and backup control cards, as each independently accesses the same database without needing to coordinate state changes.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The database card acts as an intermediary between control cards. Instead of control cards directly managing and synchronizing their own database states, they all interact with the database card as a mediator. This intermediary maintains a centralized, consistent view of protocol state information, eliminating the need for complex peer-to-peer synchronization between master and backup control cards.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Ease of operation

If the entire system is reset when a control card fails, then simplicity of failover is improved, but loss of information increases due to resetting the database

Engineering Contradiction:

Improvefailover simplicityVSAvoidprotocol state information loss

Core Design Contradiction:

Ease of operationVSLoss of information

Solution Approach 1:

The patent segments the reset operation by decoupling the control card reset from the database reset. When a control card fails, only that specific control card is reset, while the database card maintains its state information intact. This segmentation allows the system to recover from control card failures without losing protocol state information stored in the database.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The database card serves as a cushioning mechanism that preserves protocol state information before control card failures occur. By independently maintaining and protecting this information, the database card cushions the system against information loss during failover events, allowing control cards to be reset without losing critical state data.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Device complexity

If control plane processing and database maintenance are integrated, then device complexity is reduced, but productivity decreases due to resource constraints during failover

Engineering Contradiction:

Improvesystem structureVSAvoidfailover performance

Core Design Contradiction:

Device complexityVSProductivity

Solution Approach 1:

The patent segments control plane processing and database maintenance into separate functional components. The database card is dedicated to maintaining protocol state information, while control cards focus on processing control plane messages. This segmentation allows each component to optimize its performance independently, improving overall system productivity during normal operation and during failover events.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The database card as an intermediary enables efficient resource utilization. Control cards can quickly access protocol state information through standardized interfaces without burdening the control plane processing functions with database maintenance tasks. This separation allows parallel optimization of processing speed and data management, improving failover performance.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS9912530B2Method and apparatus for hitless failover in networking systems using single database

Publication Date: 2018.03.06 JUNIPER NETWORKS INC

AI summary

A device includes a master control card that performs control plane processing, a backup control card, where the backup control card takes over control plane processing if the master control card goes out of service, and a database card that connects to the master control card and the backup control card, where the database control card stores information relating to control plane processing. A method of achieving hitless failover in a network element includes detecting that a master control card of the network element has gone out of service, designating the backup control card as a new master control card of the network element, establishing communication with a database card of the network element, and retrieving protocol states information from the database card.