OSPF Nonstop Routing Link Derivation

Solution Overview

Problem

In existing OSPF Nonstop Routing (NSR) systems, synchronization of link state advertisements (LSAs) between active and standby OSPF instances is resource-intensive and can lead to delays and inconsistencies, especially in large networks, due to the need to synchronize all LSAs, including virtual neighbors, which complicates switchover processes and impacts network reliability and efficiency.

Innovation Solution

The approach involves maintaining a FULL adjacency with neighbor network elements by installing LSAs in both active and standby OSPF instances, allowing the standby OSPF instance to directly retrieve virtual neighbor information from LSAs upon activation, thereby reducing the need for synchronization and minimizing the time required for switchover, ensuring timely delivery and data consistency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If all LSAs including virtual neighbors are synchronized between active and standby OSPF instances, then data consistency is maintained, but synchronization time increases and routing processor burden increases

Engineering Contradiction:

Improvedata consistencyVSAvoidsynchronization time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent extracts virtual neighbor information from the LSA synchronization process by maintaining it separately in the standby OSPF instance's neighbor data structure. This allows virtual neighbors to be pre-configured without requiring real-time synchronization during switchover, reducing synchronization time while maintaining data consistency.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent applies preliminary action by pre-configuring virtual neighbor information in the standby OSPFinstance's neighbor data structure before switchover occurs. This advance preparation eliminates the need for real-time synchronization of virtual neighbors during the switchover process, reducing both synchronization time and routing processor burden.

Inventive Principle:

Principle #10Preliminary action

2Reliability

If all LSAs including virtual neighbors are synchronized between active and standby OSPF instances, then data consistency is maintained, but routing processor burden increases

Engineering Contradiction:

Improvedata consistencyVSAvoidrouting processor burden

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent extracts virtual neighbor information from the LSA synchronization process by maintaining it separately in the standby OSPF instance's neighbor data structure. This separation reduces the amount of data that needs to be synchronized during switchover, thereby reducing routing processor burden while maintaining data consistency.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent applies preliminary action by pre-configuring virtual neighbor information in the standby OSPFinstance's neighbor data structure before switchover occurs. This advance preparation eliminates the need for real-time synchronization of virtual neighbors during the switchover process, reducing both synchronization time and routing processor burden.

Inventive Principle:

Principle #10Preliminary action

3Reliability

If virtual neighbor information is synchronized during switchover, then data consistency is maintained, but switchover time increases

Engineering Contradiction:

Improvedata consistencyVSAvoidswitchover time

Core Design Contradiction:

ReliabilityVSDuration of action of moving object

Solution Approach 1:

The patent extracts virtual neighbor information from the LSA synchronization process by maintaining it separately in the standby OSPF instance's neighbor data structure. This allows virtual neighbors to be pre-configured without requiring real-time synchronization during switchover, reducing switchover time while maintaining data consistency.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent applies preliminary action by pre-configuring virtual neighbor information in the standby OSPFinstance's neighbor data structure before switchover occurs. This advance preparation eliminates the need for real-time synchronization of virtual neighbors during the switchover process, reducing both synchronization time and switchover time.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS8913485B2Open shortest path first (OSPF) nonstop routing (NSR) with link derivation

Publication Date: 2014.12.16 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)

AI summary

OSPF NSR with link derivation synchronization is described. When a network element having an active OSPF instance and a standby OSPF instance attempts to create a FULL adjacency with a neighbor network element using a neighbor data structure of the active OSPF instance, and if and when a switch causes the second OSPF instance to act as the active OSPF instance, neighbor information is retrieved from the LSAs of the standby OSPF instance and a link is derived between the network element and the neighbor network element based on the retrieved neighbor information. In one embodiment, the standby OSPF instance retrieves virtual neighbor information from its LSAs and derives a virtual link between the network element and the neighbor network element based on the retrieved virtual neighbor information without having to synchronize the neighbor information between the active and standby OSPF instance.