Anycast-Based Router Redirection for Partial Routing Tables

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Solution Overview

Problem

Network operators face the challenge of frequent hardware upgrades or replacements due to growing Internet routing tables and forwarding tables, which are memory-intensive, leading to high costs and service interruptions, especially for equipment that has reached its capacity limits.

Innovation Solution

Implementing a system that redirects outbound traffic from constrained routers to helper routers with full routing tables, allowing network operators to continue using existing equipment by distributing helper routers across the network, thereby reducing the need for immediate upgrades and maintaining service resilience.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If routers store full routing tables to handle all routing decisions, then routing capability is improved, but memory requirements and hardware costs increase

Engineering Contradiction:

Improverouting capabilityVSAvoidmemory requirements

Core Design Contradiction:

ReliabilityVSQuantity of substance

Solution Approach 1:

The patent introduces helper routers as intermediary devices that store full routing tables and assist constrained routers with limited memory. Constrained routers forward packets they cannot route to helper routers, which then perform the routing lookup and forward packets to their destinations. This mediator approach allows routers with limited memory to maintain routing capability without storing complete routing tables themselves.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Productivity

If hardware is upgraded frequently to keep pace with growing routing tables, then routing performance is improved, but capital costs and service interruptions increase

Engineering Contradiction:

Improverouting performanceVSAvoidcapital costs

Core Design Contradiction:

ProductivityVSLoss of energy

Solution Approach 1:

The patent makes helper routers serve multiple functions: they act as standard routers for their own traffic, serve as routing table repositories for constrained routers, and function as fallback routing resources when primary routing paths are unavailable. This multi-functionality justifies the investment in helper routers by providing multiple benefits beyond just extending the operational life of constrained hardware.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Duration of action of stationary object

If traffic is redirected to helper routers, then operational life of constrained hardware is extended, but network latency increases

Engineering Contradiction:

Improveoperational life of hardwareVSAvoidnetwork latency

Core Design Contradiction:

Duration of action of stationary objectVSLoss of time

Solution Approach 1:

The patent implements anycast addressing where multiple helper routers advertise the same anycast prefix with different routing metrics. Constrained routers select the helper router with the best (lowest) metric, ensuring traffic is directed to the geographically or topologically closest helper router. This local optimization minimizes the detour distance and reduces latency while still allowing constrained routers to operate with limited memory.

Inventive Principle:

Principle #3Local quality

4Loss of time

If helper routers are distributed throughout the network, then latency is reduced, but device complexity increases

Engineering Contradiction:

ImprovelatencyVSAvoidnetwork configuration

Core Design Contradiction:

Loss of timeVSDevice complexity

Solution Approach 1:

The patent merges the routing table storage function with the routing decision function by having helper routers perform both roles. Instead of separating routing information storage from routing execution across multiple specialized devices, the helper router consolidates these functions, simplifying the overall network architecture while distributing intelligence throughout the network to reduce latency.

Inventive Principle:

Principle #5Merging (Combining)

Data Source

PatentUS9160657B2Anycast-based internet protocol redirection to alleviate partial routing tables

Publication Date: 2015.10.13 AT&T INTELLECTUAL PROPERTY I L P

AI summary

Systems and methods are described that instruct routers having constrained hardware/memory to redirect all outbound traffic to a helper router. The helper router contains a full routing table that can forward any packet to its destination. In a large service provider network, helper routers may be distributed at multiple locations across the network. Since packets must detour through the helper router, the distributed helper routers minimize latency.