Intra-Area Aggregate LSP for Seamless MPLS Scalability
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Solution Overview
Problem
Multicast communication in seamless Multi-Protocol Label Switching (MPLS) architectures faces scalability issues due to the inability of existing multicast MPLS protocols to effectively manage point-to-multipoint connectivity across thousands of provider edge routers within multiple routing areas of an Autonomous System (AS).
Innovation Solution
The implementation of inter-area point-to-multipoint (P2MP) segmented label switched paths (LSPs) is achieved by stitching together intra-area segments within each routing area, allowing for the establishment of intra-area aggregate LSPs using label switching hierarchy, which enables the aggregation of congruent or partially congruent intra-area segments, thereby improving scalability and reducing overhead.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multicast MPLS protocols are used to provide seamless MPLS across multiple routing areas, then multicast communication coverage is improved, but protocol scalability deteriorates due to inability to manage thousands of PE routers
Solution Approach 1:
The patent divides the seamless MPLS architecture into multiple routing areas, each with its own multicast MPLS domain. This segmentation allows each area to independently manage its PE routers and multicast sessions, preventing the protocol from needing to scale across the entire AS and thus resolving the scalability issue while maintaining broad multicast coverage.
Solution Approach 2:
The patent introduces area border routers (ABRs) as intermediary devices between different routing areas. These ABRs perform multicast routing functions at the area boundary, acting as mediators that enable multicast communication across area boundaries without requiring every PE router in every area to maintain full multicast state, thereby improving scalability.
2Measurement precision
If intra-area segments are tracked individually across multiple routing areas, then routing precision is improved, but overhead increases due to tracking leaf node forwarding information
Solution Approach 1:
The patent merges the tracking of intra-area segments from multiple inter-area P2MP LSPs into a single intra-area aggregate LSP when the segments are congruent or partially congruent. This consolidation reduces the quantity of routing information and state that must be maintained while preserving the precision of intra-area routing through the aggregate LSP structure.
Solution Approach 2:
The intra-area aggregate LSP serves multiple functions: it carries traffic for multiple congruent or partially congruent inter-area P2MP LSPs simultaneously, provides a unified routing structure for intra-area segments, and reduces overhead by consolidating state information. This multi-functionality allows a single structure to handle what would otherwise require multiple separate tracking mechanisms.
3Quantity of substance
If LSP hierarchy with aggregation is implemented, then overhead is reduced by aggregating congruent intra-area segments, but device complexity increases due to hierarchy management
Solution Approach 1:
The LSP hierarchy is segmented into two distinct levels: inter-area P2MP LSPs that span multiple routing areas and intra-area aggregate LSPs that operate within individual areas. This segmentation allows each level to be managed independently with appropriate complexity, reducing the overall management burden while enabling aggregation to reduce overhead.
Solution Approach 2:
The patent applies aggregation selectively only to congruent or partially congruent intra-area segments, rather than attempting to aggregate all segments universally. This partial action approach reduces overhead where aggregation is beneficial while avoiding the complexity of managing non-congruent segments through the hierarchy, thus optimizing the complexity-overhead tradeoff.
Data Source
AI summary
In general, techniques are described for providing multicast communication in a seamless MPLS architecture, in which thousands of PE routers within different routing areas of the same AS require P2MP connectivity to receive multicast communication. In particular, the techniques enable building inter-area P2MP segmented LSPs within an AS by stitching together intra-area segments of the inter-area P2MP segmented LSPs. The techniques provide LSP hierarchy with segmentation to enable aggregation of congruent intra-area segments within a routing area into an intra-area aggregate LSP. The AS may use the BGP as the inter-area label distribution protocol, and each routing area within the AS may independently select one of the multicast MPLS protocols as its intra-area label distribution protocol. The seamless MPLS architecture may be used by private network instances, such as multicast VPLS instances, MVPN instances, and IP multicast instances.