Virtual IP Mobility Across Heterogeneous Networks

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Solution Overview

Problem

Current mobile communication technologies face challenges in maintaining seamless connectivity as mobile nodes move across different wireless networks and address spaces, leading to disruptions in IP address changes, which break existing TCP connections and exhaust IP address resources.

Innovation Solution

The implementation of a method using invariant virtual IP addresses for host identification and routable actual IP addresses that change as the mobile node moves, with a DHCP server and NAT device managing these addresses to maintain connection integrity across heterogeneous networks.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a mobile node changes its IP address when moving between subnets or networks, then the mobile node can maintain routable connectivity in the new network, but existing TCP connections are broken

Engineering Contradiction:

Improveconnection continuityVSAvoidnetwork mobility

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent segments the IP addressing function into two distinct components: a permanent virtual IP address that remains unchanged for connection identification, and a temporary actual IP address that changes with network location. This segmentation allows the system to maintain connection reliability through the invariant virtual address while adapting to network mobility through the changeable actual address.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces a NAT device as an intermediary between the mobile node and the network. This NAT device maintains the mapping between virtual and actual IP addresses, enabling it to translate packets and preserve TCP connections even when the actual IP address changes. The intermediary absorbs the complexity of address management while maintaining simple, stable addresses for end hosts.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Quantity of substance

If Network Address Translation (NAT) devices are used to combat IP address exhaustion, then IP address resources are conserved, but complexity is added to the network architecture

Engineering Contradiction:

ImproveIP address resourcesVSAvoidnetwork architecture

Core Design Contradiction:

Quantity of substanceVSDevice complexity

Solution Approach 1:

The patent makes the NAT device universal by giving it multiple functions: it performs traditional address translation to conserve IP resources, maintains virtual-to-actual address mappings for mobile nodes, and preserves TCP connections across network changes. This multi-functionality consolidates what would otherwise require separate systems into a single NAT device.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent changes the address space parameters by introducing a virtual IP address space that is separate from the actual routable IP address space. This parameter separation allows the system to conserve actual IP addresses while providing each mobile node with a unique, permanent virtual address for connection identification.

Inventive Principle:

Principle #35Parameter changes

3Device complexity

If the mobile node uses a single IP address for both host identification and network routing, then the system is simple, but mobility across heterogeneous networks cannot be supported

Engineering Contradiction:

Improveaddressing systemVSAvoidcross-network mobility

Core Design Contradiction:

Device complexityVSAdaptability or versatility

Solution Approach 1:

The patent segments the dual function of IP addressing into separate roles: the virtual IP address handles host identification and connection tracking, while the actual IP address handles network routing and reachability. This functional segmentation enables mobility across heterogeneous networks while maintaining simplicity in connection management.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent adds another dimension to the addressing system by introducing a second address space layer. Instead of a single flat IP address serving multiple purposes, the system uses a two-dimensional addressing approach where virtual addresses provide stability for connections and actual addresses provide flexibility for routing, allowing mobility without sacrificing connection integrity.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Data Source

PatentUS7453852B2Method and system for mobility across heterogeneous address spaces

Publication Date: 2008.11.18 ALCATEL LUCENT SA

AI summary

A mobile node includes a processor, a network interface, and a storage device having computer program code for execution by the processor. The computer program code includes a network layer for transmitting and receiving packets and an intermediate driver that transmits packets to the network layer and receives packets from the network layer using a virtual internet protocol (IP) address to identify the mobile node. The intermediate driver transmits packets to the network interface and receives packets from the network interface using a routable actual IP address to identify the mobile node. The intermediate driver permits the actual IP address to change when the mobile node moves from a first subnet to a second subnet without a corresponding change in the virtual IP address. A corresponding NAT associates the virtual IP address with a second actual IP address when the NAT is notified that the mobile node is in the second subnet.