Hierarchical Segmented LSPs for MPLS Computational Load Reduction
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Solution Overview
Problem
MPLS networks with RSVP-TE face significant computational and network load burdens due to the large number of Label Switched Paths (LSPs) in fully meshed topologies, leading to performance degradation and increased resource consumption as the number of routers increases.
Innovation Solution
Implementing a hierarchical segmented MPLS network architecture where routers are grouped by levels of LSP tunneling hierarchy, limiting the number of LSPs determined by each router, and configuring RSVP-TE logic to bundle refresh messages, use explicit-null labels, and adaptive reservation styles to reduce the computational load and network load.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a fully meshed MPLS network topology is used to ensure comprehensive connectivity and resource reservation, then network coverage and connectivity are improved, but computational load and network load increase significantly
Solution Approach 1:
The network is divided into hierarchical levels (Level 0 to Level N) where routers at each level maintain LSPs only to routers at adjacent levels, rather than maintaining full mesh connectivity. This segmentation reduces the number of LSPs from O(n²) in a fully meshed network to O(n) in the hierarchical structure, significantly reducing computational load while preserving network connectivity through the hierarchical path structure.
Solution Approach 2:
The patent introduces a hierarchical dimension to the network topology, organizing routers into multiple levels. This dimensional change transforms the flat fully-meshed topology into a structured hierarchy, allowing routers to achieve connectivity through indirect paths via higher-level routers, thereby reducing direct LSP requirements while maintaining network-wide reachability.
2Reliability
If the number of LSPs is increased to improve network resource reservation capability, then service quality and resource allocation are improved, but performance degradation and resource consumption increase
Solution Approach 1:
Resource reservation is segmented across hierarchical levels, where RSVP-TE operations are performed primarily between adjacent levels. This reduces the scope of resource reservation computations from network-wide to localized level transitions, maintaining resource allocation capability while reducing the performance overhead associated with processing numerous LSP refresh messages.
Solution Approach 2:
The patent applies partial action by implementing selective LSP establishment only between hierarchical levels rather than all possible router pairs. This partial approach provides sufficient resource reservation capability for most traffic flows while avoiding the excessive computational burden of maintaining LSPs for all possible source-destination pairs in a fully meshed network.
3Reliability
If RSVP-TE refresh messages are sent frequently to maintain LSP state, then LSP reliability is improved, but network load and bandwidth consumption increase
Solution Approach 1:
The refresh message traffic is segmented and localized to adjacent hierarchical levels only, rather than being propagated across the entire network mesh. This segmentation reduces the total number of refresh messages in the network, as each router only exchanges RSVP-TE refreshes with its hierarchical neighbors, thereby reducing network bandwidth consumption while maintaining LSP state reliability through regular localized refreshes.
Data Source
AI summary
A network may include a first set of routers at a first level of a multi-protocol label switched tunneling hierarchy and a second set of routers at a second level of the multi-protocol label switched tunneling hierarchy, the second set of routers connected to the first set of routers in a partially meshed topology. The network may also include a hierarchical segmented label switched path. The hierarchical segmented label switched path may include a forwarding adjacency label switched path including a subset of the first set of routers, and a label switched path coupled to the forwarding adjacency label switched path, the label switched path including a subset of the second set of routers.