NAT Traversal via Determination Packets in Multilayer Networks
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In multilayer NAT environments, existing NAT traversal methods are limited in effectiveness, particularly when NAT devices lack port mapping settings like UPnP, leading to difficulties in establishing peer-to-peer (P2P) communication, resulting in variable connectivity and user dissatisfaction.
Innovation Solution
A communication device and method that includes a connection environment check unit, a determination purpose port mapping command unit, and a determination packet generation unit to collect and utilize NAT information, enabling port mapping and NAT traversal even in environments without UPnP support by identifying and utilizing the port number issuance rules of lower layer NAT devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional NAT traversal methods (STUN, UPnP) are used, then P2P communication can be established in simple NAT environments, but they fail or have variable effectiveness in multilayer NAT environments where lower layer NAT devices lack port mapping functions
Solution Approach 1:
The communication device performs preliminary actions by transmitting determination packets to lower layer NAT devices before actual P2P communication begins. These packets elicit binding information (MAC address, IP address, port number) in advance, allowing the device to construct proper NAT traversal paths before data transmission starts. This resolves the contradiction by preparing necessary connection information proactively, ensuring reliability while adapting to various NAT configurations.
Solution Approach 2:
The system implements feedback mechanisms where the communication device receives binding information from lower layer NAT devices in response to determination packets. This feedback loop allows the device to learn the actual port numbers and addresses assigned by NAT devices, enabling dynamic adaptation to different NAT configurations. The feedback mechanism ensures reliable P2P communication by using actual assigned addresses rather than assuming fixed mappings.
2Ease of operation
If port mapping commands are issued to lower layer NAT devices, then P2P communication can be established, but the complexity of managing multiple NAT devices and port mappings increases
Solution Approach 1:
The lower layer NAT devices perform self-configuration by automatically generating binding information when receiving determination packets. The NAT devices autonomously manage their own port mappings without requiring complex external control. This self-service approach simplifies P2P connection establishment for the communication device while keeping NAT management complexity contained within the NAT devices themselves through automatic binding generation and response.
Solution Approach 2:
The determination packet acts as an intermediary mechanism that facilitates communication between the communication device and lower layer NAT devices. Instead of directly managing complex port mappings, the device uses these standardized determination packets to exchange binding information. This intermediary approach simplifies the operation of establishing P2P connections while the NAT devices handle the complexity of their own port management internally.
3Measurement precision
If the communication device obtains WAN-side port numbers from determination packets, then accurate NAT traversal can be achieved, but additional packets and processing steps are required
Solution Approach 1:
The communication device transmits determination packets as a preliminary action to obtain accurate WAN-side port numbers from lower layer NAT devices before actual data transmission begins. This advance acquisition of precise port information ensures that when P2P communication starts, the device already has the accurate binding information needed for proper NAT traversal. The time investment in obtaining precise port numbers upfront is justified by the need for accurate connection establishment.
Solution Approach 2:
The system uses feedback from determination packets to obtain accurate port numbers. The lower layer NAT devices respond with binding information containing the actual WAN-side port numbers assigned to them. This feedback mechanism ensures measurement precision by using real assigned port numbers rather than assumptions. The additional processing steps are necessary to extract and utilize this feedback information for accurate NAT traversal.
Data Source
AI summary
A terminal device includes a connection environment check unit, a determination purpose port mapping command unit which issues a port mapping command to a lower layer NAT device, and a determination packet generation unit which generates a determination packet which is source-routed. Additionally, a determination packet transmitting unit transmits the determination packet, a determination packet receiving unit receives the determination packet transmitted from the determination packet transmitting unit, passing through the upper layer NAT device a and the lower layer NAT device a and arriving at the terminal device a, and a port number obtainment unit obtains a WAN-side port number of the lower layer NAT device a indicated in the received determination packet.