Empty Route Mechanism Limits BGP Withdrawal Messages
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Solution Overview
Problem
Conventional Multicast VPN arrangements generate excessive BGP withdrawal messages upon route failures, leading to inefficient use of network resources and degraded network performance.
Innovation Solution
Configuring network devices to generate an 'empty route' in response to actual route failures, which reduces the number of BGP withdrawal messages by sending a multicast join message and an unreachability indicator message, causing additional devices to delete multiple actual routes represented by the empty route.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional MVPN arrangements are used to handle IP multicast traffic, then multicast capability is provided between customer sites, but excessive BGP withdrawal messages are generated upon route failures leading to degraded network performance
Solution Approach 1:
The system performs preliminary action by generating an empty route in advance that represents multiple actual routes to a next-hop network device. When a route failure occurs, this pre-established empty route allows the system to send a single withdrawal message that automatically withdraws all routes represented by the empty route, rather than generating multiple individual withdrawal messages for each actual route. This preliminary preparation of the empty route structure enables efficient bulk route withdrawal upon failure.
Solution Approach 2:
The invention merges multiple actual routes into a single empty route representation. The empty route consolidates multiple actual routes that share common attributes (such as the same next-hop network device) into one abstract route object. This merging allows the system to treat multiple routes as a single unit for withdrawal purposes, thereby reducing the number of BGP withdrawal messages from multiple individual messages to a single consolidated message.
2Reliability
If multiple BGP withdrawal messages are sent upon route failure to ensure proper route propagation, then route failure is properly communicated to all relevant devices, but network resources are inefficiently used due to message overhead
Solution Approach 1:
The empty route serves multiple functions simultaneously: it represents multiple actual routes, acts as a consolidation mechanism for route withdrawal, and enables single-message propagation of failure information to multiple downstream devices. This multi-functionality allows the system to maintain reliable route failure communication while minimizing message overhead, as the single withdrawal message associated with the empty route achieves what would otherwise require multiple separate messages.
Data Source
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AI summary
A first network device is configured to originate an actual route by sending a multicast join message to a particular next-hop network device, and in conjunction with originating the actual route, to generate an empty route associated with the next-hop network device for use in limiting a number of withdrawal messages that would otherwise result upon a failure in the actual route. The first network device may be further configured to generate an unreachability indicator message for the empty route indicating that the next-hop network device is unreachable responsive to the failure in the actual route, and to send the unreachability indicator message for the empty route to one or more additional network devices, with the unreachability indicator message causing each such additional network device to delete multiple actual routes to the next-hop network device that are represented by the empty route.