MPLS Dataplane Continuity in Link State Routing
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Solution Overview
Problem
Conventional shortest path algorithms in networks that use link state protocols do not account for MPLS dataplane continuity, leading to dropped MPLS packets when traversing paths that are not MPLS capable, resulting in complex multi-topology approaches to ensure end-to-end connectivity.
Innovation Solution
A modified Dijkstra's computation that incorporates a new reachability TLV to track MPLS dataplane capability on a per-adjacency basis, allowing for the detection of MPLS end-to-end continuity while determining shortest paths within the link state topology, thereby programming both IP and MPLS dataplanes accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional shortest path algorithms are used to determine shortest cost paths, then path determination is simple and fast, but MPLS dataplane continuity is not ensured and packets are dropped
Solution Approach 1:
The patent merges the shortest path determination process with MPLS continuity detection by modifying Dijkstra's algorithm to simultaneously compute both functions. The algorithm traverses the link state topology while detecting MPLS capability at each node, combining what were previously separate operations into a unified process that ensures end-to-end MPLS continuity without requiring multiple topologies.
Solution Approach 2:
The patent changes the parameters of the shortest path algorithm by introducing MPLS capability detection as a new criterion. Instead of solely optimizing for cost, the modified algorithm considers both cost and MPLS continuity, using parameters such as MPLS capability flags and path cost to determine optimal paths that satisfy both routing and continuity requirements.
2Reliability
If multiple topologies are used to ensure MPLS continuity, then end-to-end connectivity is ensured, but computational complexity increases substantially
Solution Approach 1:
The patent makes the link state topology serve multiple functions: it is used both for standard shortest path determination and for MPLS continuity detection. By modifying Dijkstra's algorithm to detect MPLS capability while traversing the existing link state topology, the system eliminates the need for separate MPLS topologies, allowing a single universal topology to serve both routing and continuity verification purposes.
Solution Approach 2:
The patent combines the shortest path computation and MPLS continuity detection into a single algorithmic process. The modified Dijkstra's algorithm simultaneously determines shortest paths and detects MPLS capability along those paths, merging two separate functions into one unified operation that reduces computational overhead.
3Adaptability or versatility
If nodes that do not support MPLS are included in shortest paths, then path flexibility is improved, but MPLS packets are dropped
Solution Approach 1:
The patent applies local quality by detecting and evaluating MPLS capability at each individual node along the potential path. The modified Dijkstra's algorithm examines whether each node supports MPLS and uses this local information to determine whether to include that node in the final shortest path, ensuring that only paths with end-to-end MPLS capability are selected for MPLS traffic.
Data Source
AI summary
A method is performed at a source node in a network of nodes configured with a link state protocol, and in which at least some of the nodes are enabled for multiprotocol label switching (MPLS). The node discovers and stores a link state topology representing the nodes of the network, links between the nodes, path-costs for the links, and whether each link is enabled or not enabled for MPLS. The node determines one or more shortest paths from the source node to a destination node among the nodes based on traversing the link state topology and, while the node traverses the link state topology, detects whether each shortest path supports or does not support MPLS end-to-end dataplane continuity. The node programs an IP dataplane with each shortest path, and programs an MPLS dataplane with ones of the one or more shortest paths that support the end-to-end MPLS continuity.