NAT Gateway with HTTP Redirection for IPv4 Address Sharing

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Solution Overview

Problem

The exhaustion of IPv4 addresses and the limitations of existing NAT devices in supporting multiple WEB servers with concurrent access from a global space to a local space, leading to increased processing loads and usability issues for WEB clients.

Innovation Solution

A communication device with a host table and transfer table that stores global and local addresses and ports, allowing for HTTP redirection and translation between WEB clients and servers, enabling sharing of a single global address among multiple WEB servers without terminating TCP connections.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If a gateway device with NAT function is used to share a single global address among multiple WEB servers, then the number of required global IP addresses is reduced, but the device becomes very expensive due to large-scale data center and high-volume memory requirements

Engineering Contradiction:

Improvenumber of global IP addressesVSAvoiddevice cost

Core Design Contradiction:

Quantity of substanceVSEase of manufacture

Solution Approach 1:

The patent divides the address translation function into two separate components: a redirection device that performs HTTP redirection based on host headers, and a gateway device that performs simple NAPT. This segmentation allows the gateway device to have minimal memory requirements while still enabling multiple WEB servers to share a single global address through coordinated operation with the redirection device.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The redirection device acts as an intermediary between the WEB client and the gateway device. It intercepts HTTP requests, performs host header analysis, and redirects requests to the appropriate WEB server using simple NAPT at the gateway device. This intermediary approach eliminates the need for the gateway device to perform complex HTTP message analysis and TCP connection termination.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Adaptability or versatility

If a gateway device performs HTTP message analysis and TCP connection termination to enable address translation, then multiple WEB servers can be accessed, but the processing load increases and usability for WEB clients deteriorates

Engineering Contradiction:

Improveability to access multiple WEB serversVSAvoidusability for WEB clients

Core Design Contradiction:

Adaptability or versatilityVSEase of operation

Solution Approach 1:

The patent extracts the complex HTTP message analysis and TCP connection termination functions from the gateway device and relocates them to the redirection device. The gateway device is left with only the simple NAPT function, which has minimal processing requirements. This extraction maintains the ability to access multiple WEB servers while significantly reducing processing load and improving usability.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

Instead of having the gateway device perform complex HTTP analysis and then translate addresses, the patent inverts the approach: the redirection device performs HTTP analysis first, determines the target WEB server, and then the gateway device performs simple address translation. This inversion simplifies the gateway device's workload while maintaining full functionality.

Inventive Principle:

Principle #13The other way round (Inversion)

3Quantity of substance

If IP masquerade or NAPT is used to translate addresses, then a single global address can be shared, but multimedia applications and concurrent access from multiple devices to multiple servers are not supported

Engineering Contradiction:

Improvenumber of global addressesVSAvoidsupport for multimedia applications and concurrent access

Core Design Contradiction:

Quantity of substanceVSAdaptability or versatility

Solution Approach 1:

The patent implements dynamic port allocation and management in the redirection device, allowing it to track multiple TCP connections and their corresponding WEB servers. This dynamic approach enables concurrent access from multiple devices to multiple servers while maintaining the single global address sharing capability provided by NAPT.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system implements feedback mechanisms where the redirection device monitors HTTP requests, tracks connection states, and dynamically redirects traffic to appropriate WEB servers. This feedback loop enables support for multimedia applications and concurrent access while maintaining efficient use of the single global address through coordinated NAPT at the gateway device.

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS8954603B2Communication device and communication method of the same

Publication Date: 2015.02.10 OKI ELECTRIC INDUSTRY CO LTD

AI summary

In the gateway device, the global address (GA) of the host table is set to the same value, and the GA and the local port (LP) of the transfer table are respectively set to the same value. In the IP packet analysis unit, the sorting unit analyzes the packet from the WEB client and sorts the destination of the packet, the redirection unit supplies the GA and the global port (GP) to the WEB client that has made a request by the packet according to a result of analysis to perform redirection, and the translation/transfer unit analyzes the packets transmitted through the sorting unit, translates the addresses (GA/LA: local address) and the ports (GP/LP) respectively with each other and transfers the translated packets, and then the procedure after connection establishment is repeated.