Gateway DNS Resolution for Mobile IP Reachability

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Solution Overview

Problem

Dynamic IP address allocation in mobile IP networks leads to significant communication bandwidth and delay overhead due to the need for constant updates of IP address databases, and NAT bindings can only be created if communication is initiated by a device in the private network, limiting inter-network communication.

Innovation Solution

Implementing a gateway-based address resolution mechanism that enhances gateways with DNS server functionalities, allowing recursive or iterative DNS queries to resolve IP addresses and create NAT bindings even if communication is not initiated by a device in the private network, thereby eliminating the need for a central IP address database and enabling communication between devices in different networks.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If dynamic IP address allocation is implemented in mobile IP networks, then IP address flexibility and device mobility are improved, but communication bandwidth overhead and delay increase due to constant database updates

Engineering Contradiction:

ImproveIP address flexibilityVSAvoidcommunication bandwidth overhead

Core Design Contradiction:

Adaptability or versatilityVSLoss of energy

Solution Approach 1:

The patent extracts the DNS server functionality from the centralized IP address database and places it at the gateway level. This allows local resolution of IP addresses without requiring constant updates to a central database, thereby reducing communication bandwidth overhead while maintaining dynamic IP allocation capabilities.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The gateway is enhanced with DNS server functionalities, making it a multi-functional device that can perform both routing and domain name resolution. This eliminates the need for separate centralized database updates and reduces communication overhead.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Reliability

If NAT bindings are required for communication between private and public networks, then network security is improved, but communication versatility deteriorates as bindings can only be created when initiated by private network devices

Engineering Contradiction:

Improvenetwork securityVSAvoidinter-network communication capability

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent inverts the traditional NAT binding creation process. Instead of requiring private network devices to initiate bindings, the gateway's DNS server can create NAT bindings on behalf of private network devices when receiving DNS queries from public network devices. This allows public network devices to initiate communication with private network devices without requiring prior binding initiation from the private side.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The gateway acts as an intermediary that mediates between public and private networks. It receives DNS queries from public network devices, creates appropriate NAT bindings, and facilitates communication without requiring direct initiation from private network devices, thus maintaining security while enabling versatile communication.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Ease of operation

If a central IP address database is maintained for mobile devices, then IP address management is simplified, but communication delay increases due to frequent database updates

Engineering Contradiction:

ImproveIP address managementVSAvoidcommunication delay

Core Design Contradiction:

Ease of operationVSLoss of time

Solution Approach 1:

The patent segments the centralized IP address database functionality and distributes it to individual gateways. Each gateway maintains its own DNS server that can resolve IP addresses locally without requiring centralized database updates, thereby reducing communication delay while maintaining manageable IP address allocation.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The gateway's DNS server performs self-service by maintaining local IP address resolution capabilities. It can resolve domain names to IP addresses without requiring external database updates, eliminating the need for frequent centralized database synchronization and reducing communication delay.

Inventive Principle:

Principle #25Self-service

Data Source

PatentUS8924574B2Apparatus, systems, and methods for IP reachability in a communications network

Publication Date: 2014.12.30 CISCO TECHNOLOGY INC

AI summary

In a system and method for establishing communications in a communications network, a network service provider can assign IP addresses to mobile devices dynamically to conserve IP address resources. A network service provider can also implement network address translation to further conserve IP address resources and to provide improved security. If a requestor seeks to obtain an IP address of a mobile device and the address is a local address, the system determines if the mobile device has a network address translation (NAT) binding that associates the IP address of the mobile device with a public IP address. If the mobile device does not have a NAT binding, the system creates a NAT binding that associates the IP address of the mobile device with a public IP address.