MPLS Ring Topology Fast Re-route Optimization
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Solution Overview
Problem
In MPLS networks with ring topologies, the transition of traffic from a protected LSP to a back-up LSP often results in bandwidth issues due to shared links being traversed twice, leading to increased bandwidth requirements that can exceed link capacity.
Innovation Solution
A method and system that reroute traffic from a protected LSP to a back-up LSP to avoid shared links by identifying and removing these links, using alert packets to initiate and manage the protection switch, thereby optimizing bandwidth usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traffic is routed from protected LSP to back-up LSP upon link failure, then network reliability is improved, but bandwidth requirements on shared links are doubled causing bandwidth issues
Solution Approach 1:
The patent segments the ring topology into distinct path sections by identifying the point of local repair (PLR) and merge point (MP). Traffic is routed through the back-up LSP in a controlled manner, passing through the PLR once and the MP once, rather than traversing shared links multiple times. This segmentation prevents bandwidth doubling on any single link while maintaining protection functionality.
Solution Approach 2:
The patent changes the routing dimension by introducing optimized next-hop selections at the PLR and MP. Instead of following the traditional back-up LSP path that retraverses shared links, traffic is redirected through alternative next-hops that exploit the ring topology structure, effectively adding a new dimensional approach to path selection that avoids bandwidth congestion.
2Reliability
If manual configuration of back-up LSP is performed to ensure disjointed paths, then path reliability is improved, but device complexity and manual intervention requirements increase
Solution Approach 1:
The patent enables the network to automatically determine and execute optimized rerouting decisions without manual intervention. When a link failure is detected, the PLR automatically identifies the MP and selects appropriate next-hops based on the ring topology structure. This self-service mechanism eliminates the need for manual back-up LSP configuration while maintaining reliable protected paths.
Solution Approach 2:
The patent introduces dynamic path selection capabilities where the back-up LSP routing is not statically predetermined but adaptively determined based on real-time failure conditions. The PLR dynamically selects next-hops to the MP based on the specific failure scenario, allowing the system to optimize paths on-demand rather than relying on pre-configured static routes.
3Reliability
If back-up LSP traverses shared links twice (once in each direction), then protection coverage is improved, but bandwidth capacity requirements are exceeded
Solution Approach 1:
The patent segments the traffic flow into distinct segments: the protected LSP segment up to the failure point, and the back-up LSP segment from the PLR to the MP. By carefully controlling which segments use which path and ensuring that the back-up path does not retraverse shared links, the total traversal distance on any single link is reduced from twice the ring circumference to at most the diameter of the ring.
Data Source
AI summary
A method performed on a network element employing Multi-protocol Label Switching (MPLS) to optimize bandwidth in a ring topology network including a back-up Label Switch Path (LSP) for a protected LSP by re-routing traffic onto the back-up LSP to avoid shared links between the protected LSP and back-up LSP, including receiving a first labeled packet from another label switch router (LSR) in the back-up LSP, the first labeled packet indicating protection switch of data from the protected LSP to the back-up LSP, determining whether a shared link in the ring topology network exists between the protected LSP and the back-up LSP, rerouting traffic for the protected LSP onto an optimized back-up LSP to remove the shared link, receiving a second labeled packet indicating that a protection switch of data, and restoring routing of the traffic onto the protected LSP in response to receiving the second labeled packet.