NAT-PT Gateways for IPv4 to IPv6 Translation

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Solution Overview

Problem

Conventional VPNs face performance issues and reliability concerns when connecting IPv4 nodes across IPv6 networks, especially when an IPv6 node is coupled to a private IPv4 network with a NAT, requiring modifications to existing NATs to include IPv6 routers, which is impractical, and assuming global public IPv4 addresses, limiting private address usage.

Innovation Solution

Configuring first and second gateways to establish network address translation-protocol translation (NAT-PT) state entries for translating IPv4 packets into IPv6 packets for transmission via an IPv6 network, allowing IPv4 nodes in private networks to communicate without tunneling protocols, using prescribed IPv6 prefixes and dynamic address assignment to manage address conflicts.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional VPNs are used to connect IPv4 nodes across IPv6 networks, then network connectivity is achieved, but performance issues arise including bandwidth limitations, latency, and reliability concerns

Engineering Contradiction:

Improveconnection reliabilityVSAvoidlatency

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent introduces NAT-PT gateways as intermediary devices that translate IPv4 packets into IPv6 packets, enabling direct communication between IPv4 nodes across an IPv6 network without relying on conventional VPN tunneling through public networks. This intermediary translation mechanism eliminates the performance degradation associated with VPN encapsulation and routing.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Adaptability or versatility

If the 6 to 4 proposal is used to enable IPv6 nodes in NAT networks, then connectivity is achieved, but existing NATs must be modified to include IPv6 routers with 6 to 4 mechanism

Engineering Contradiction:

ImproveIPv6 compatibilityVSAvoidNAT modification complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

Instead of modifying existing NATs to include IPv6 functionality (6 to 4 mechanism), the patent inverts the approach by introducing separate NAT-PT gateways that perform IPv4 to IPv6 translation. This allows existing NATs to remain unchanged while still enabling IPv6 nodes to communicate with IPv4 networks through the gateway translation mechanism.

Inventive Principle:

Principle #13The other way round (Inversion)

3Adaptability or versatility

If the 6 to 4 protocol is used, then IPv6 nodes can communicate, but global public IPv4 addresses are assumed, limiting private address usage

Engineering Contradiction:

Improveaddress mapping capabilityVSAvoidaddress conflict

Core Design Contradiction:

Adaptability or versatilityVSObject-generated harmful factors

Solution Approach 1:

The patent implements dynamic address assignment and conflict detection mechanisms in NAT-PT gateways. When an IPv6 node needs to communicate with an IPv4 network, the gateway dynamically assigns a unique private IPv4 address from its pool, checks for conflicts with existing assignments, and manages the address lifecycle. This dynamic approach enables flexible use of private IPv4 addresses without requiring global public addresses.

Inventive Principle:

Principle #15Dynamics

4Speed

If direct communication between IPv4 nodes via IPv6 network is enabled, then latency-sensitive applications are optimized, but NAT-PT state management and address conflict resolution complexity increases

Engineering Contradiction:

Improvecommunication speedVSAvoidgateway state management

Core Design Contradiction:

SpeedVSDevice complexity

Solution Approach 1:

The patent implements self-service mechanisms in NAT-PT gateways including automatic NAT-PT state entry creation when IPv4 packets are translated, automated conflict detection and resolution for assigned IPv4 addresses, and dynamic state management. The gateways autonomously handle address assignment, conflict detection, and translation state maintenance without requiring manual intervention, thereby managing the increased complexity through automation.

Inventive Principle:

Principle #25Self-service

Data Source

PatentUS7411967B2Private network gateways interconnecting private networks via an access network

Publication Date: 2008.08.12 CISCO TECHNOLOGY INC

AI summary

Gateways providing connectivity for respective private IPv4 networks to an IPv6 network establish communications between IPv4 nodes in the private network. Network address translation-protocol translation (NAT-PT) state entries are created by gateway pairs enabling translation of IPv4 packets between first and second IPv4 nodes in respective first and second IPv4 private networks into IPv6 packets for transmission via the IPv6 network. Each NAT-PT state entry specifies the IPv6 addresses for the first and second IPv4 nodes, and the IPv4 addresses used to identify the first and second IPv4 nodes in the corresponding private IPv4 network. Each gateway is configured for generating the IPv6 address for each local IPv4 node based on prepending its corresponding assigned private IPv4 address with a corresponding prescribed IPv6 prefix assigned to the gateway. Hence, gateways can dynamically establish communications between private networks without tunneling protocols, enabling deployment of latency-sensitive applications such as Voice over IP.