NAT Traversal via Redirect Packet Mapping

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Solution Overview

Problem

Current multimedia communication protocols face challenges in traversing through Network Address Translation (NAT) devices in NAPT mode, leading to inefficient use of public network IP addresses and communication failures, as NAT devices cannot share public IP addresses among multiple private network terminals.

Innovation Solution

A method that establishes a mapping relationship between private and public network addresses, allowing private network terminals to access public networks using a common address, enabling media stream interaction by sending redirect packets and replacing source addresses in NAT devices, without requiring modifications to firewalls or NAT devices.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If NAT device uses NAPT mode to save public network IP address resources, then IP address resource efficiency is improved, but multimedia communication protocol traversal capability deteriorates

Engineering Contradiction:

Improvepublic network IP address resourcesVSAvoidmultimedia communication protocol traversal

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The patent introduces a redirect packet as an intermediary mechanism between the private network terminal and the NAT device. This redirect packet carries the public network IP address and port information, enabling the NAT device to establish a mapping relationship without requiring the terminal to directly access the public network. The redirect packet serves as a mediator that bridges the private network terminal and the public network, allowing multimedia communication to traverse through the NAT device in NAPT mode.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent applies preliminary action by having the private network terminal send a redirect packet before the actual multimedia communication begins. This redirect packet pre-establishes the mapping relationship between the private network address and the public network address at the NAT device. By performing this address mapping setup in advance, the system enables subsequent media streams to traverse the NAT device successfully without requiring additional modifications to the NAT device or firewall.

Inventive Principle:

Principle #10Preliminary action

2Reliability

If NAT device assigns public network IP address to private network terminal dynamically, then communication capability is improved, but IP address resource efficiency deteriorates

Engineering Contradiction:

Improvecommunication capabilityVSAvoidIP address resource efficiency

Core Design Contradiction:

ReliabilityVSQuantity of substance

Solution Approach 1:

The patent enables a single public network IP address to serve multiple private network terminals by using the redirect packet mechanism. Instead of assigning dedicated public IP addresses to each terminal, the system allows multiple terminals to share the same public IP address through the redirect packet that carries the necessary address mapping information. This multi-functionality approach significantly improves IP address resource efficiency while maintaining communication capability for multiple terminals.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Object-affected harmful factors

If NAT device rejects UDP packets from public network to private network, then security is improved, but multimedia communication capability deteriorates

Engineering Contradiction:

ImprovesecurityVSAvoidmultimedia communication capability

Core Design Contradiction:

Object-affected harmful factorsVSReliability

Solution Approach 1:

The redirect packet acts as an intermediary that enables UDP packets to traverse the NAT device securely. Instead of directly sending UDP packets from the public network to the private network (which would be rejected by the NAT device), the system uses the redirect packet mechanism to establish a safe communication path. The redirect packet carries the necessary mapping information, allowing the NAT device to forward UDP packets correctly while maintaining security controls.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The system performs preliminary action by having the private network terminal send the redirect packet before receiving UDP packets from the public network. This pre-establishes the mapping relationship at the NAT device, ensuring that subsequent UDP packets can be forwarded correctly. This preliminary setup allows the NAT device to maintain its security functions while enabling necessary multimedia communication.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS7706370B2Method of implementing multimedia protocol passing through network address transform device

Publication Date: 2010.04.27 HUAWEI TECH CO LTD

AI summary

The present invention discloses a method of implementing traversal of multimedia protocols through Network Address Translation device, wherein the Network Address Translation (NAT) device establishes a mapping relationship between address of a terminal in a private network and address of a terminal in a public network, and enables the terminal in the private network to access the public network with a common address, so as to implement the interaction of media streams between the terminal in the private network and the terminal in the public network, in which the common address is a address of the private network for accessing the public network.