BGP-LS Selective Route Refresh Mechanism
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Solution Overview
Problem
The existing BGP route refresh mechanism causes unnecessary churn and communication overhead by refreshing all network topology information for a given address family identifier (AFI) and subsequent address family identifier (SAFI), even when only a subset of information needs to be updated.
Innovation Solution
An advanced route refresh message is introduced that extends the standard BGP ROUTE-REFRESH message with additional parameters such as route distinguisher, autonomous system (AS) number, link-state identifier (LS-ID), protocol, instance identifier, and network layer reachability information (NLRI) type, allowing for selective refresh of network topology information by specifying specific parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the existing BGP route refresh mechanism is used to refresh all network topology information for a given AFI and SAFI, then the routing information can be updated, but unnecessary churn and communication overhead occur
Solution Approach 1:
The patent segments the network topology information by introducing hierarchical filtering levels (route refresh filter level 0-3) that allow selective refresh of specific subsets of routing information. Instead of refreshing all routes for a given AFI/SAFI, the system divides the routing information into manageable segments that can be independently refreshed based on specific criteria such as route distinguisher, AS number, LS-ID, protocol, instance identifier, and NLRI type.
Solution Approach 2:
The patent applies local quality by allowing different parts of the routing information to have different refresh characteristics. The route refresh filter levels enable specific subsets of routes to be marked with different refresh behaviors, so that only the necessary local portions are refreshed rather than the entire routing table, thereby reducing communication overhead while maintaining reliability.
2Reliability
If the existing BGP route refresh mechanism is used to refresh all network topology information for a given AFI and SAFI, then the routing information can be updated, but unnecessary churn occurs
Solution Approach 1:
By segmenting the routing information refresh process into hierarchical levels, the patent allows stable portions of the routing table to remain unchanged while only refreshing specific segments that require updates. This segmentation prevents unnecessary churn in stable routing information while ensuring that updates are propagated where needed, thus maintaining both reliability and stability.
Solution Approach 2:
The patent implements partial action by refreshing only the necessary subset of routing information rather than performing a complete refresh. The route refresh filter levels enable the system to apply exactly the right amount of action needed - refreshing specific routes when changes occur while leaving other routes untouched, thereby reducing churn and maintaining routing information stability.
Data Source
AI summary
A method is implemented by a network device acting as a border gateway protocol (BGP) speaker in a network including a plurality of network devices. The method implements selective route refresh for BGP link state (BGP-LS) to reduce communication overhead in sharing network topology information with other BGP speakers in the network. The method includes receiving an advanced route refresh message from a peer BGP speaker, where the advanced route refresh message includes an address family identifier (AFI), a subsequent address family identifier (SAFI), and one or more parameters associated with the AFI and the SAFI. The method further includes determining a subset of network topology information that matches the AFI, the SAFI, and the one or more parameters in the received advanced route refresh message and transmitting the subset of network topology information to the peer BGP speaker.