NAT System for Mobile IP in Private Networks
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Solution Overview
Problem
Current NAT systems hinder the operation of mobile IP protocol in private networks by altering private IP addresses to public ones, leading to inefficiencies in address usage and incompatibility with existing NAT technology.
Innovation Solution
A NAT system that introduces a swap address option field in IP headers, allowing the NAT device to swap source and destination addresses without requiring mapping tables or port numbers, enabling seamless mobile IP support in private networks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a NAT device translates private IP addresses to public IP addresses, then IP address conservation is improved, but mobile IP protocol compatibility deteriorates
Solution Approach 1:
The patent introduces a home agent as an intermediary between the mobile node and the external network. The home agent maintains the binding between the mobile node's private address and its public address, enabling mobile IP functionality to work through the NAT device without requiring the NAT device itself to understand mobile IP protocols.
Solution Approach 2:
The patent segments the address translation process into two parts: the NAT device performs standard address translation, while the home agent performs mobile IP-specific address binding and packet routing. This segmentation allows each component to perform its specialized function without interfering with the other.
2Adaptability or versatility
If the home agent uses the translated public IP address for packet routing, then NAT compatibility is improved, but mobile node address accuracy deteriorates
Solution Approach 1:
The home agent acts as an intermediary that receives packets destined for the mobile node's public address, translates them to the private address, and forwards them to the mobile node. This intermediary function ensures that packets are accurately routed to the correct mobile node while maintaining compatibility with NAT devices.
Solution Approach 2:
The home agent performs preliminary address binding before packet routing by maintaining a binding cache that maps public addresses to private addresses. This preliminary action ensures that when packets arrive, the correct translation can be performed immediately without delay or error.
3Measurement precision
If mapping tables are used for address translation, then address routing accuracy is improved, but system complexity increases
Solution Approach 1:
The patent extracts the complex mapping table management functionality from the NAT device and places it in the home agent. The NAT device performs simple address translation, while the home agent maintains the mobile IP-specific binding information. This extraction reduces the complexity burden on the NAT device while maintaining routing accuracy.
Data Source
AI summary
A NAT system for supporting mobile IP in private networks and its method. A mobile node moves from its home network to a foreign private network and obtains a CoA from the private network. The mobile node sends a registration packet to a home agent in the home network. The registration packet has a swap address option field. A NAT device in the private network swaps the source address with the swap address of the registration packet, and translates the source address into the public address of the NAT device, thereby sending the registration packet to the home agent. After receiving the registration packet, the home agent responds a registration reply packet having a swap address option field filled in the CoA. The NAT device swaps the destination address with the swap address of the registration reply packet, thereby sending the registration reply packet to the mobile node.