Two-Level ECMP Table for Weighted Cost Multi-Pathing
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Solution Overview
Problem
Traditional equal cost multi-path (ECMP) forwarding tables become excessively large when unequal weights are assigned to paths, leading to hardware resource constraints and increased costs in packet switching networks.
Innovation Solution
A method for generating a multi-level ECMP forwarding table based on the number of ports and their associated weights, utilizing a two-level table structure with a first level that includes port identifiers or pointers to a second level table, reducing the overall number of entries and maintaining weighted distribution ratios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If traditional ECMP forwarding tables are used with unequal weights assigned to paths, then weighted packet distribution can be achieved, but the forwarding table size becomes excessively large
Solution Approach 1:
The forwarding table is divided into multiple levels (first level table and second level tables). The first level table contains a smaller set of entries that reference groups of paths, while the second level tables contain the detailed path information. This segmentation reduces the size of any single forwarding table while maintaining the ability to represent weighted distributions across multiple paths.
Solution Approach 2:
The patent introduces a hierarchical dimension to the forwarding table structure, transitioning from a single-level flat table to a multi-level nested structure. This dimensional change allows the system to represent the same weighted path information more compactly by organizing data across multiple hierarchical levels rather than requiring all paths to be enumerated in a single table.
2Adaptability or versatility
If traditional ECMP forwarding tables are used with unequal weights, then path weighting can be implemented, but hardware resource constraints are exceeded
Solution Approach 1:
The forwarding information is segmented across multiple tables and levels, reducing the memory and processing requirements of any single hardware component. The first level table requires fewer entries, and the second level tables can be structured to optimize hardware implementation, thereby fitting within existing hardware resource constraints while maintaining path weighting capability.
Solution Approach 2:
The multi-level forwarding table structure implements a nested organization where the first level table contains references to second level tables, which in turn contain detailed path information. This nested structure allows hierarchical organization of forwarding data, reducing the immediate hardware resource requirements at each level while preserving the complete path weighting information.
3Adaptability or versatility
If traditional ECMP forwarding tables are used with unequal weights, then weighted cost multi-pathing can be achieved, but the table entries increase significantly
Solution Approach 1:
The large set of forwarding table entries is segmented into a first level table with fewer entries that reference multiple second level tables. This segmentation reduces the number of entries that must be present in any single table, making the implementation of weighted cost multi-pathing feasible without requiring an excessively large number of table entries in one location.
Solution Approach 2:
The patent adds a hierarchical dimension to the forwarding table structure, organizing entries across multiple levels rather than requiring all weighted path entries to exist in a single flat table. This dimensional transformation allows the system to represent weighted cost multi-pathing with a more manageable distribution of table entries across the hierarchical structure.
Data Source
AI summary
This disclosure provides systems, methods, and apparatus for providing a network switch for implementing weighted cost multi-pathing (WCMP). In some implementations, the switch can implement equal cost multi-pathing (ECMP) using ECMP forwarding tables. The ECMP forwarding table may include more than one output port associated with a destination address of an incoming packet. The ECMP forwarding table may become undesirably large if unequal weights were assigned to the output ports. A multi-level ECMP table can be implemented that can allow assigning weights to the output ports while being relatively small. The multi-level ECMP table can include a first level where each entry includes at most a single output port. A second level can include entries having one or more output ports.