Session Proxy Address Translation for NAT Peer-to-Peer Connectivity
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Solution Overview
Problem
Nodes behind a Network Address Translation (NAT)-enabled router lack true peer-to-peer connectivity, preventing the use of certain Internet protocols like SIP and disrupting TCP and UDP-based services, as internal addresses are not visible to external networks, necessitating application layer gateways for connectivity.
Innovation Solution
A method and system that obtain and translate addresses between a first network and a second network, replacing internal addresses with external addresses in session establishment requests, allowing peer-to-peer multimedia sessions without relying on specific application layer gateways, using network address translation information and a session proxy entity to manage address mappings and send requests through a NAT-enabled router.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If NAT is used to enable multiple hosts to access the Internet using a single IP address, then address conservation and network connectivity are improved, but true peer-to-peer connectivity and visibility of internal addresses to external networks deteriorate
Solution Approach 1:
The patent introduces a Session Initiation Protocol (SIP) server as an intermediary that mediates between NAT-protected hosts and external networks. The SIP server receives session establishment requests, translates addresses using NAT information, and forwards requests to the appropriate internal hosts, enabling peer-to-peer connectivity while maintaining NAT protection.
Solution Approach 2:
The patent performs preliminary address translation by obtaining NAT information before session establishment and pre-translating addresses in session description protocols. This preliminary action ensures that when session requests are sent, the addresses are already in the correct format for peer-to-peer communication through the NAT router.
2Adaptability or versatility
If application layer gateways are used to provide connectivity over NAT-enabled routers, then protocol compatibility is improved, but device complexity and infrastructure requirements worsen
Solution Approach 1:
The patent makes the SIP server universal by integrating multiple functions: it acts as a session manager, address translator, and protocol adapter simultaneously. This multi-functionality eliminates the need for separate application layer gateways, reducing infrastructure complexity while maintaining broad protocol compatibility for SIP, TCP, and UDP services.
3Ease of manufacture
If end-to-end peer-to-peer communication is implemented, then infrastructure investment is reduced, but address visibility and connectivity through NAT deteriorate
Solution Approach 1:
The SIP server serves as a lightweight intermediary that enables end-to-end peer-to-peer communication while solving the address visibility problem. It translates addresses in session descriptions and routing information, allowing direct peer-to-peer media streams without requiring complex gateway infrastructure, thus maintaining low investment requirements while ensuring address visibility through NAT.
Data Source
AI summary
The invention relates to a method where a first address (121) from a first network (185) is obtained to a mobile node (180). Network address translation information is received from a network node (140) to the mobile node (180), the network node (140) being connected to a second network (150). An address mapping is indicated between the first address (121) and a second address (101) to the network node (140), the second address (101) being associated with the second network (150). A session establishment request is obtained. The request comprises instances of the first addresses (121) and third addresses (120). The first addresses (121) are replaced with the second addresses (101) in the request. An address mapping is indicated between the third address (120) and a fourth address (100) to the first network node (140). The session establishment request is sent to a remote network node (190) from the mobile node (180).