Border Router Failover Entries for WAN Path Optimization
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Solution Overview
Problem
In network environments, existing technologies face challenges in ensuring fast convergence and minimizing packet loss during WAN interface failures, as they lack efficient mechanisms for quick traffic flow redirection and failover, leading to potential traffic loops and visibility issues.
Innovation Solution
The implementation of failover entries and GRE key extensions in routing control tables and GRE Key-Nexthop Binding Tables allows border routers to quickly switch traffic flows to backup paths when a WAN interface fails, using pre-established backup paths and tunnel keys to avoid traffic loops and ensure seamless failover.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional routing protocols are used for WAN interface failure detection and recovery, then the system maintains simplicity in routing management, but the convergence time is slow and packet loss occurs during failover
Solution Approach 1:
The patent pre-establishes backup paths and configures failover entries in advance before failures occur. When a WAN interface failure is detected, the border router immediately switches to the pre-configured backup path without requiring real-time routing calculations, achieving sub-second failover performance
Solution Approach 2:
The patent introduces a control entity that acts as an intermediary between border routers and policy servers. This control entity distributes failover entries to border routers, enabling fast local failover decisions without requiring continuous communication with the policy server during failure events
2Productivity
If real-time routing decisions are made by the policy server based on traffic flow information, then the routing optimization is maximized, but the response time during interface failures increases
Solution Approach 1:
The policy server pre-calculates and distributes failover entries containing backup path information to border routers in advance. During actual failures, border routers use these pre-computed entries for immediate switching without waiting for policy server responses, achieving both optimization and speed
Solution Approach 2:
The patent separates routing functions into two parts: the policy server handles long-term routing optimization and failover entry generation, while border routers handle real-time failover execution using local failover entries. This segmentation allows each component to operate at its optimal speed
3Device complexity
If backup paths are not pre-established, then the network configuration is simpler, but traffic loops may occur during failover and packet loss increases
Solution Approach 1:
The control entity acts as an intermediary that automatically generates and distributes failover entries containing pre-established backup path information. This automated process reduces configuration complexity while ensuring reliable backup paths are in place, preventing traffic loops during failover
Solution Approach 2:
The system implements feedback mechanisms where border routers report interface status and traffic flow information to the control entity and policy server. This feedback enables dynamic updates of failover entries to maintain optimal backup paths while preventing traffic loops through continuous monitoring
Data Source
AI summary
According to one aspect, a control entity (such as a policy server) in communication with a plurality of border routers in a network, generates failover entries for one or more traffic flows. Each failover entry specifies a backup path to be used by a border router when the border router determines that a wide area network interface of the border router has failed. The control entity sends the failover entries to each of the border routers. A border router operating in a network stores failover entries for one or more traffic flows. For packets received at the border router either from a local area network interface or via a tunnel from another border router, when the border router detects that the wide area network interface has failed, the border router determines how to handle the packets based on the stored failover entries.