OSPF NSR Synchronization via Cumulative LSA Acknowledgments
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Solution Overview
Problem
Current OSPF Nonstop Routing (NSR) technologies face challenges in efficiently synchronizing active and standby OSPF instances, leading to high resource utilization and computational overhead due to the need for individual acknowledgments and lookups for each link state advertisement (LSA), which impacts network performance and scalability.
Innovation Solution
Implementing a method where the active OSPF instance maintains an on-hold LSA linked list and sends LSAs to a standby OSPF instance via inter-process communication (IPC), with acknowledgments only sent for the last LSA in a group, reducing the number of acknowledgments and lookups required, and using an in-process LSA linked list to manage acknowledgments efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If individual LSA acknowledgments are sent for each LSA during OSPF NSR synchronization, then reliability of synchronization is improved, but resource utilization and computational overhead increase significantly
Solution Approach 1:
The patent combines multiple individual LSA acknowledgments into a single cumulative acknowledgment mechanism. The standby OSPF instance sends one acknowledgment message that covers all LSAs processed during synchronization, eliminating the need for separate acknowledgment messages for each LSA. This merging approach maintains synchronization reliability while dramatically reducing the number of IPC messages and computational resources required.
Solution Approach 2:
The patent implements preliminary action by having the standby OSPFinstance process and buffer multiple LSAs before sending a single acknowledgment to the active OSPFinstance. The standby instance maintains a buffer of processed LSAs and sends cumulative acknowledgments, effectively preparing multiple LSAs in advance and reducing the frequency of communication overhead.
2Measurement precision
If individual LSA lookups are performed for each acknowledged LSA, then accuracy of synchronization tracking is improved, but processing time and computational overhead increase
Solution Approach 1:
The patent merges multiple individual LSA lookup operations into a single batched lookup mechanism. Instead of performing separate database lookups for each acknowledged LSA, the system performs one lookup operation to retrieve all accumulated LSAs from the buffer, significantly reducing processing time while maintaining accurate synchronization tracking through the cumulative acknowledgment mechanism.
3Reliability
If frequent IPC messages are sent for LSA synchronization, then synchronization completeness is improved, but network overhead and resource consumption increase
Solution Approach 1:
The patent applies preliminary action by having the standby OSPFinstance buffer and accumulate multiple LSAs before transmitting them to the active instance. This allows the system to perform synchronization in larger batches, reducing the total number of IPC messages while maintaining complete synchronization through the cumulative acknowledgment mechanism.
Solution Approach 2:
The patent merges multiple LSA synchronization operations into fewer, larger IPC messages. By combining multiple LSAs into single batched transmissions and using cumulative acknowledgments, the system reduces the quantity of individual IPC messages while preserving synchronization completeness through the accumulated LSA buffer and cumulative acknowledgment protocol.
Data Source
AI summary
A network element is configured to reduce the synchronization costs for implementing Open Shortest Path First (OSPF) Nonstop routing (NSR). The reduced synchronization costs are achieved by reducing the number of acknowledgement messages that are needed to be sent though reliable inter-process communication (IPC) between the active OSPF instance and the standby OSPF instance. The number of acknowledgement messages is reduced by tracking the link state advertisements (LSAs) that have been sent by the active OSPF instance to the standby OSPF instance and by the standby OSPF replying with an acknowledgement of only the last LSA in a group of LSAs received from the active OSPF instance, where the group can have a variety of boundaries such as a group of LSAs in an IPC message. This avoids having a significant number of acknowledgement messages sent through the IPC.