BGP Route Re-advertisement Timing for Traffic Loss Reduction
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Solution Overview
Problem
In multi-homed network connections, traffic loss occurs due to immediate re-advertisement of routes by primary routers before they are fully installed in the forwarding plane, leading to 'black-holing' issues, and existing solutions like route acknowledgement messages present scalability challenges.
Innovation Solution
Implementing a BGP marker to indicate the end of route download, allowing the primary router to defer re-advertisement until the last route is installed, and requesting a Route-ACK only for the last route of an address family, thereby reducing the number of Route-ACKs required.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the primary router immediately re-advertises routes upon receiving them from a multi-homed router, then the routing information is propagated quickly to BGP peer routers, but traffic loss occurs because the routes are not yet fully installed in the forwarding plane
Solution Approach 1:
The patent applies preliminary action by ensuring that routes are fully installed in the forwarding plane before re-advertisement to BGP peer routers. The control plane receives routes from the multi-homed router, installs them in the forwarding plane first, and only then re-advertises them. This preliminary installation action prevents traffic loss by ensuring forwarding capability exists before traffic is redirected to the primary path.
2Reliability
If route acknowledgement messages are implemented for each route to ensure proper installation in the forwarding plane, then traffic loss is prevented, but the system complexity and processing overhead increase significantly
Solution Approach 1:
The patent merges multiple individual route acknowledgement messages into a single consolidated acknowledgement. Instead of requiring separate Route-ACK messages for each route installed in the forwarding plane, the system combines all route installation confirmations into one aggregated acknowledgement message sent from the forwarding plane to the control plane. This reduces message overhead and processing complexity while maintaining reliability.
3Reliability
If the primary router waits for all routes to be installed before re-advertisement, then traffic loss is avoided, but the delay in route propagation to BGP peer routers increases
Solution Approach 1:
The patent maintains continuity of useful action by keeping the backup forwarding path active during the route installation process. While the primary router waits for routes to be installed in the forwarding plane before re-advertisement, traffic continues to flow through the backup path without interruption. This ensures continuous service delivery without complete停滞, even though the primary path activation is delayed until installation completion.
Data Source
AI summary
This disclosure describes techniques to reduce traffic loss for a Border Gateway Protocol (BGP) session by delaying re-advertisement of routes received from a newly re-established multi-homed router by a primary router until all the routes are installed in a forwarding plane of the primary router. The techniques of this disclosure make use of a BGP marker received from the multi-homed router that indicates the end of a route download for an address family. Upon receiving the BGP marker, a control plane of the primary router requests a route acknowledgement message (Route-ACK) from the forwarding plane for only the last route of the address family received before the BGP marker. When the control plane receives the Route-ACK indicating that the last route has been installed in the forwarding plane, the primary router initiates re-advertisement of the routes to other BGP peer routers.