IP Network Double-Link Failure Recovery Using Precomputed Backup Ports
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Solution Overview
Problem
Current IP networks face challenges in rapidly recovering from double-link failures without introducing high complexity or resource usage, as existing rerouting schemes often result in service disruptions and require redundant bandwidth or complex maintenance.
Innovation Solution
The method determines first and secondary backup ports for each router in an IP network to ensure 100% failure recovery from double-link failures by using a routing path graph and integer linear programming, with a heuristic algorithm to minimize hardware complexity and avoid dead loops.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If routing protocols perform failure advertising, route recalculation and routing table update to recover from failures, then various types of failures can be dealt with, but the recovery time reaches seconds which causes long service disruptions and packet drops
Solution Approach 1:
The patent pre-calculates and stores backup paths for all possible single-link failures before failures occur. When a failure happens, routers immediately switch to pre-computed backup paths without waiting for route recalculation, achieving fast recovery in tens of milliseconds while maintaining the ability to handle various failure types
Solution Approach 2:
The patent segments the routing problem into primary paths and multiple backup paths for each destination. By maintaining separate pre-computed backup paths for different failure scenarios, the system can quickly select the appropriate backup path when a specific link fails, avoiding the need for complete route recalculation
2Loss of time
If lower layer protection establishes backup connections in advance to achieve fast recovery, then failure recovery is completed within tens of milliseconds, but redundant bandwidth is reserved and the IP layer is not independent in survivability
Solution Approach 1:
The patent makes backup paths serve multiple purposes: they function as protection paths during failures and as alternative forwarding paths during normal operation. This multi-functionality allows the network to achieve fast failure recovery without permanently reserving redundant bandwidth, as backup paths only activate when needed
Solution Approach 2:
The patent implements dynamic path selection where routers can switch between primary and backup paths based on real-time network conditions and failure states. Backup paths are dynamically activated only when failures occur, allowing the system to maintain low resource usage during normal operation while providing fast recovery capability when needed
3Loss of time
If IP fast rerouting maintains backup port for each destination to achieve fast failure recovery, then service disruption is minimized, but the complexity of determining and coordinating backup ports increases
Solution Approach 1:
The patent enables each router to independently determine its own backup ports and forwarding paths using a standardized algorithm. Routers autonomously compute backup paths to their destinations without requiring complex centralized coordination or signaling between routers, simplifying the overall system complexity while maintaining fast recovery capability
4Reliability
If existing rerouting schemes are used for double-link failure recovery, then failure recovery can be achieved, but service disruptions occur and resource usage increases
Solution Approach 1:
The patent pre-calculates backup paths specifically for double-link failure scenarios before failures occur. When double-link failures happen, routers immediately activate pre-computed backup paths, achieving fast recovery and maintaining service continuity without the disruptions caused by reactive rerouting schemes
Solution Approach 2:
The patent introduces a path graph data structure as an intermediary that pre-organizes backup paths for double-link failures. This path graph serves as a lookup table that routers can quickly query to determine appropriate backup paths, enabling fast double-link failure recovery without complex real-time calculations or resource allocation
Data Source
AI summary
Backup ports for a first router of the survivable network are determined so that the first router can reach a destination node in the event of a double link failure. A routing path graph having the destination node is accepted. The routing path graph includes one or more links terminated by one or more primary ports of the first router. For each router of at least a part of the routing path graph, assuming that a link terminated by a primary port of the first router is removed, a first part of the routing path graph including the destination node and a second part of the routing path graph (sub-graph) separated from the first part are defined. Two exits for the sub-graph to reach the graph are determined. A primary backup port and a secondary backup port are determined for the first router using the determined two exits.