BGP Router Graceful Restart Using Local Prefix Store
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Solution Overview
Problem
The conventional graceful restart approach for BGP routers in computer networks is slow due to the need to recompute routes and consume significant system resources, leading to temporary loss of routing information and increased latency in network convergence.
Innovation Solution
A local store on the restarting router is used to store redundant copies of prefixes with selection preferences, allowing immediate computation of best paths and transmission of the end-of-RIB message, thereby speeding up the restart process without awaiting route information from peers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the conventional graceful restart approach is used, then the BGP router can recover from a shutdown, but the convergence time is long and system resources are significantly consumed
Solution Approach 1:
The patent applies preliminary action by pre-computing and storing candidate best paths in a data structure before the BGP router shuts down. When the router restarts, these pre-computed paths are immediately available for installation, eliminating the need to recompute routes during restart. This resolves the contradiction by enabling fast recovery (improving reliability) without requiring time-consuming route recomputation (reducing convergence time).
Solution Approach 2:
The patent applies local quality by maintaining a localized data structure containing candidate best paths specific to each adjacency. Instead of globally recomputing all routes, only the locally stored candidate paths for affected adjacencies are installed. This selective local approach reduces system resource consumption while achieving fast convergence, resolving the contradiction between reliability and time loss.
2Reliability
If the conventional graceful restart approach is used, then the BGP router can recover from a shutdown, but system resources are significantly consumed for route recomputation
Solution Approach 1:
The patent applies preliminary action by pre-computing candidate best paths before shutdown and storing them in a data structure. During restart, the router simply installs these pre-computed paths rather than recomputing them, dramatically reducing CPU and memory resources required during the recovery process. This resolves the contradiction by maintaining reliable recovery capability while minimizing system resource consumption.
Solution Approach 2:
The patent applies copying by creating and storing copy representations of candidate best paths in a data structure before shutdown. These copied path representations can be quickly reinstated during restart without requiring full route recomputation. This copying approach reduces system resource usage during recovery while maintaining reliable BGP router recovery capability.
3Measurement precision
If the restarting router awaits receipt of route information from peers, then route accuracy is ensured, but the restart process is slow
Solution Approach 1:
The patent applies preliminary action by pre-computing candidate best paths and storing them before the BGP router shuts down. Upon restart, the router immediately installs these pre-computed paths without waiting for route information from peers, significantly reducing restart duration. The pre-computed paths ensure route accuracy is maintained while eliminating the time delay of awaiting peer updates.
Solution Approach 2:
The patent applies beforehand cushioning by preparing and storing candidate best paths in advance before shutdown occurs. This pre-prepared cushion of route information allows the router to immediately resume forwarding traffic upon restart without waiting for peer updates, thus reducing restart time while maintaining route information accuracy through the pre-validated candidate paths.
Data Source
AI summary
A technique is provided for graceful restart of a Border Gateway Protocol (BGP) router that uses a local store on the restarting router that stores prefixes on all routes or the “group best path” information on all BGP peers having a common Autonomous System (AS) number. This local store is used to run best path computations on the restarting router, rather than first awaiting receipt of route information from peers to speed the restart process. Updates are then transmitted to peers using the best path data and an end-of-Routing Information Base (RIB) message it transmitted by the restarting router to indicate that all information has now been sent by the restarting router. Thereafter the restarting router processes incoming updates from peers as received (or these peers routes are timed-out), remaining stale paths are deleted and any changed best paths, based upon the newly received updates, are then transmitted to peers.