SIP Message Redundant Address Encoding for NAT Traversal
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Solution Overview
Problem
Existing communication networks face challenges in setting up communication sessions across networks with address translation equipment (NAT) due to issues with NAT traversal, where signal protocols like SIP/SDP struggle to exchange public addresses, leading to incomplete or incorrect address modifications, causing communication failures.
Innovation Solution
A method where a communication client encodes and redundantly adds its physical address and port numbers in signal messages using specific fields within the SDP protocol, ensuring these addresses and port numbers are not modified by NAT equipment, allowing unmodified addresses to be used for session setup.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If NAT equipment modifies IP headers to translate addresses, then address translation between private and public networks is achieved, but physical addresses in SIP/SDP messages remain unmodified causing communication failures
Solution Approach 1:
The patent segments address information into two distinct locations within the signal message: a first location containing the physical address and a second location containing coded information representing the same physical address. This segmentation allows the NAT equipment to modify only the IP header addresses while the coded address in the second location remains unmodified, ensuring reliable communication session setup.
Solution Approach 2:
The coded information in the second location acts as an intermediary that preserves the original physical address meaning despite NAT transformations. This intermediary element allows the receiving end to correctly identify the source address without being affected by the NAT address translation, resolving the reliability issue.
2Reliability
If redundant coded address information is added to signal messages, then NAT traversal reliability is improved, but message complexity increases
Solution Approach 1:
The patent changes the parameter representation by encoding the physical address in a coded format in the second location. This parameter change allows the same address information to serve dual purposes: as unmodified original data for reliability and as translated data for network compatibility, achieving NAT traversal without excessive complexity.
Solution Approach 2:
The coded address information in the second location serves multiple functions: it preserves the original physical address for reliable communication, provides compatibility with NAT equipment, and maintains consistency across different network configurations. This multi-functionality justifies the added redundancy.
3Measurement precision
If client-based NAT traversal solutions are implemented, then address exchange accuracy is improved, but interference with network-based solutions occurs
Solution Approach 1:
By segmenting address information into separate locations (first location for physical address, second location for coded information), the patent enables client-based solutions to operate independently without interfering with network-based solutions. Each solution can process the appropriate segment of the message without conflict.
Solution Approach 2:
The patent creates a copy of the address information in the second location with coded representation. This copy allows client-based traversal mechanisms to function without disrupting network-based solutions, as both can operate on different representations of the same address data simultaneously.
Data Source
AI summary
Method of setting up a communication session (fm) between a calling communication client (C1) and a called communication client (C2), through a communication network (SN1, SN, SN2) comprising at least one address translation equipment (NAT1, NAT2). It comprises steps for transmission of signal messages (fs), transiting through address translation equipment and enabling interchange of physical addresses of communication clients to set up the communication session. This method is characterized in that at least one client transmits at least one signal message containing a physical address in a first location, and coded information containing this particular physical address in a distinct second location.