Hierarchical Addressing for Network Forwarding Table Reduction
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Solution Overview
Problem
Current network technologies, such as the Spanning Tree Protocol, do not fully utilize all network links, leading to inefficiencies and increased memory requirements for forwarding tables due to the blocking of links and the need to store a large number of MAC addresses, especially with the rise of blade servers and virtual machines.
Innovation Solution
Implementing a combination of Spanning Tree Protocol and Multipath methods that use hierarchical addresses, including switch IDs and local IDs, to forward frames, allowing core switches to learn only switch IDs and exit ports, and edge switches to learn device MAC addresses and communication paths, thereby reducing the size of forwarding tables and enabling more efficient link usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Spanning Tree Protocol is used to prevent loops, then network stability is improved, but link utilization deteriorates and forwarding table size increases
Solution Approach 1:
The patent segments the forwarding table into two distinct tables: a unicast forwarding table for known destination MAC addresses and a broadcast/flood forwarding table for unknown destinations. This segmentation allows the unicast table to be smaller while the broadcast table handles loop prevention, resolving the contradiction between stability and link utilization.
Solution Approach 2:
The patent implements dynamic learning where switches automatically learn MAC address to port mappings as traffic flows through the network. This dynamic approach allows the system to adapt to changing network conditions and optimize forwarding paths without requiring static configurations or blocking all links.
2Reliability
If all links are blocked to form tree topology, then loop prevention is improved, but network throughput deteriorates
Solution Approach 1:
The patent applies different forwarding strategies to different types of frames: unicast frames use MAC address learning and direct forwarding for high throughput, while broadcast frames use flooding for loop prevention. This local differentiation allows the system to optimize for throughput where possible while maintaining reliability where needed.
Solution Approach 2:
The patent enables continuous learning and adaptation where switches continuously monitor traffic patterns and update their forwarding tables. This continuous action allows the network to maintain optimal paths while preventing loops, improving both throughput and reliability simultaneously.
3Measurement precision
If forwarding tables store all MAC addresses, then packet forwarding accuracy is improved, but memory requirements deteriorate
Solution Approach 1:
The patent divides the forwarding table into specialized tables: a unicast forwarding table for precise MAC address forwarding and a broadcast forwarding table for loop prevention. This segmentation reduces the size of each individual table while maintaining overall forwarding accuracy, directly addressing the memory requirement issue.
Solution Approach 2:
The patent extracts the loop prevention function from the main forwarding table and places it in a separate broadcast forwarding mechanism. This extraction allows the unicast table to be optimized for accuracy with smaller size, while the broadcast table handles the additional reliability requirements.
4Quantity of substance
If hierarchical addressing is implemented, then forwarding table size is reduced, but protocol complexity increases
Solution Approach 1:
The patent segments the addressing hierarchy into two levels: global MAC addresses for end devices and local switch identifiers for network nodes. This hierarchical segmentation reduces the number of entries needed in forwarding tables at each switch, directly reducing table size while managing protocol complexity through clear structural separation.
Data Source
AI summary
Increased usage of network links is provided and smaller forwarding tables are required. A combination of STP and Multipath methods may be implemented in a network. Frames may be forwarded between switches not only according to MAC addresses, but also according to switch IDs and local IDs. Switch IDs do not need to be globally unique, but should be unique within a particular network. Local IDs need only be unique within a particular switch. Some preferred implementations allow frames to be delivered in order to devices requiring in-order delivery. Preferably, core switches need only learn the switch IDs of each core switch and each edge switch, and the appropriate exit port(s) corresponding to each switch. Preferably, the forwarding tables of each edge switch indicate the addresses of each device attached to that edge switch, the address of each device that is in communication with an attached device and the address of every other switch in the network.