Remote LFA Repair Path Bypassing PLR Node
Solution Overview
Problem
Remote Loop-Free Alternate (RLFA) mechanisms in communication networks experience inefficiencies due to back-and-forth forwarding paths that occupy excess bandwidth and prolong recovery times, especially in ring-based topologies, as they rely on Interior Gateway Protocol (IGP) convergence and involve unnecessary link usage.
Innovation Solution
The method involves pre-configuring a Point of Local Repair (PLR) node and a repair tunnel endpoint node before a link failure, allowing for the establishment of a repair path that excludes the PLR node and the protected link, using Label Distribution Protocol (LDP) and Multi-Topology (MT) capabilities to directly route traffic via the repair tunnel endpoint node, thereby avoiding unnecessary nodes and speeding up LDP convergence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If remote LFA mechanism uses back-and-forth forwarding path through PLR node, then repair path can be established, but bandwidth is occupied excessively and recovery time is prolonged
Solution Approach 1:
The patent pre-calculates and pre-sets repair paths using remote LFA before link failures occur, storing backup next-hop information and repair tunnel endpoints in advance. This eliminates the need for dynamic path computation during failures, enabling immediate traffic switching without occupying excessive bandwidth through back-and-forth forwarding.
Solution Approach 2:
The patent extracts and removes the PLR node from the repair path by establishing direct repair tunnels between upstream routers and remote LFA repair endpoints. This eliminates unnecessary detours through the PLR node, reducing bandwidth consumption while maintaining protection reliability.
2Reliability
If remote LFA mechanism uses back-and-forth forwarding path through PLR node, then repair path can be established, but recovery time is prolonged
Solution Approach 1:
The patent performs preliminary calculations of repair paths and pre-configuration of backup routing information before failures occur. Remote LFA repair endpoints and tunnel parameters are predetermined and stored, enabling immediate activation of repair paths without waiting for IGP convergence, thus significantly reducing recovery time.
Solution Approach 2:
The patent segments the repair path into independent repair tunnels that bypass the PLR node. By establishing direct tunnels from upstream routers to remote repair endpoints, the system eliminates dependency on PLR node processing and IGP convergence, enabling faster independent failure recovery.
3Adaptability or versatility
If repair path includes PLR node, then remote LFA mechanism can operate, but unnecessary nodes are involved increasing complexity
Solution Approach 1:
The patent extracts the PLR node from the repair path by establishing direct repair tunnels between upstream routers and remote LFA endpoints. This simplifies the routing logic by removing unnecessary intermediate nodes and their associated forwarding rules, reducing overall system complexity while preserving repair functionality.
Data Source
AI summary
A communication network is configured to operate a remote Loop-Free Alternate (LFA) procedure. Prior to detecting a link failure or switchover event associated with a protected link within a current path between a source node and a destination node of the communication network, a Point of Local Repair (PLR) node is configured for the protected link, and a repair tunnel endpoint node is configured for the PLR node. In response to detecting a link failure or switchover event associated with the protected link, a repair path is established between the source node and the destination node. The repair path is routed via the repair tunnel endpoint node, and the route of the repair path excludes the PLR node and the protected link.