Multi-Mode Layer 3 Packet Forwarding Device

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Solution Overview

Problem

Conventional layer 3 packet forwarding devices lack the ability to efficiently route packets using both host and longest prefix matching (LPM) tables in a varied operation mode, leading to suboptimal performance in handling different numbers of communicating hosts.

Innovation Solution

Implementing a multi-mode layer 3 packet forwarding device that operates modules in host mode, LPM mode, or hybrid mode, allowing for dynamic configuration of host and LPM tables based on expected utilization, with hardware-implemented tables for fast lookups and software tables for slower lookups, enabling efficient packet routing for both small and large numbers of hosts.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If a hardware-implemented host table is used to store entries for individual hosts, then packet forwarding lookup speed is improved, but memory space consumption increases when handling a large number of hosts

Engineering Contradiction:

Improvepacket forwarding lookup speedVSAvoidmemory space consumption

Core Design Contradiction:

SpeedVSQuantity of substance

Solution Approach 1:

The patent applies dynamics by making the packet forwarding device operable in multiple modes (host mode and LPM mode) that can be dynamically selected based on operational requirements. The mode selection mechanism allows the system to adapt between using host tables for small numbers of hosts and LPM tables for large numbers of hosts, optimizing the balance between lookup speed and memory consumption for different deployment scenarios

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the operational parameter of the packet forwarding device by introducing mode selection between host mode and LPM mode. This parameter change allows the system to switch between different forwarding mechanisms depending on the number of hosts, thereby adjusting memory space consumption while maintaining acceptable lookup performance for the given operational context

Inventive Principle:

Principle #35Parameter changes

2Quantity of substance

If an LPM table is used to combine multiple hosts into fewer route entries, then memory space usage is reduced, but lookup precision decreases for individual host routing

Engineering Contradiction:

Improvememory space usageVSAvoidlookup precision

Core Design Contradiction:

Quantity of substanceVSMeasurement precision

Solution Approach 1:

The patent applies dynamics by enabling dynamic mode selection between host mode and LPM mode based on the operational requirements and number of hosts. This allows the system to switch between precise host-level routing (host mode) and aggregated route routing (LPM mode), optimizing the balance between memory efficiency and routing precision for different deployment scenarios

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent introduces a mode selection parameter that changes the operational characteristics of the packet forwarding device. By switching between host mode and LPM mode, the system adjusts the precision level of routing lookups according to the number of hosts and operational requirements, thereby managing the trade-off between memory usage and lookup precision

Inventive Principle:

Principle #35Parameter changes

3Adaptability or versatility

If software routing tables are used to handle routing, then routing flexibility is improved, but packet forwarding speed deteriorates due to slower lookup performance

Engineering Contradiction:

Improverouting flexibilityVSAvoidpacket forwarding speed

Core Design Contradiction:

Adaptability or versatilityVSSpeed

Solution Approach 1:

The patent applies segmentation by dividing the routing functionality into distinct hardware-implemented tables (host tables and LPM tables) that operate independently. This segmentation allows the system to use hardware-accelerated lookups for common routing scenarios while maintaining software routing flexibility for less common cases, thereby achieving both speed and adaptability

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent implements multi-functionality by designing a packet forwarding device that can operate in multiple modes (host mode and LPM mode) and support both hardware and software routing tables. This universal design allows the system to adapt to different operational requirements while maintaining high performance through hardware acceleration when applicable

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS7843927B1Methods, systems, and computer program products for routing packets at a multi-mode layer 3 packet forwarding device

Publication Date: 2010.11.30 EXTREME NETWORKS INC

AI summary

The subject matter described herein includes methods, systems, and computer program products for routing packets at a multi-mode layer 3 packet forwarding device. According to one aspect, the subject matter described herein includes operating a first of at least two modules in a host mode, and operating a second of at least two modules in a longest prefix matching (LPM) mode. Operating a module in a host mode includes populating a host table and an LPM table with entries corresponding to hosts and routing layer 3 packets received by the first module using the host and LPM tables. Operating a module in an LPM mode includes populating a host table with entries corresponding to hosts, populating an LPM table with entries corresponding to variable length Internet protocol (IP) addresses and next hop addresses, and routing layer 3 packets received by the second module using the host and LPM tables.