Mobile Device NAT Mapping Detection for IPsec Tunnel Continuity
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Solution Overview
Problem
In mobile communication environments, changes in public IP addresses of untrusted non-3GPP access networks can cause IPsec tunnels to fail, leading to voice-over-WiFi call drops and NAS signaling failures when there is no accessible 3GPP radio access network or when the UE is in flight mode.
Innovation Solution
A method and device that start a timer upon receiving a service packet, detect changes in network address translation (NAT) mappings by comparing hash values, and send update requests to maintain communication continuity, ensuring the IPsec tunnel remains active even with changes in public IP addresses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the UE accesses the 3GPP network through an untrusted non-3GPP access network with NAT, then the UE can establish initial communication, but when the public IP address changes, the IPsec tunnel becomes invalid and communication continuity is lost
Solution Approach 1:
The patent applies preliminary action by proactively detecting NAT mapping changes before they cause communication failure. The UE periodically checks NAT binding status and pre-updates IPsec tunnel parameters when changes are detected, rather than waiting for tunnel failure. This prevents communication interruption by acting in advance.
Solution Approach 2:
The patent implements feedback mechanisms where the UE monitors the validity of its public IP address and NAT mappings continuously. When the UE detects that the public IP address has changed or NAT binding is invalid, it sends feedback to the network to trigger IPsec tunnel parameter updates, ensuring the tunnel remains synchronized with current network conditions.
2Reliability
If the UE monitors for packet reception to detect communication status, then the UE can identify connection failures, but the detection latency may exceed the disconnection timeout period causing service interruption
Solution Approach 1:
The patent applies periodic action by implementing regular monitoring intervals for packet reception and NAT binding validation. Instead of waiting for random packet failures, the UE periodically checks communication status at predetermined intervals, ensuring timely detection of connection issues before they impact service continuity.
Solution Approach 2:
The patent uses preliminary action by setting the timer period shorter than the disconnection timeout period, allowing the UE to detect and respond to communication failures before the network officially considers the connection dead. This early detection enables proactive tunnel updates rather than reactive recovery.
3Reliability
If the IPsec tunnel parameters are updated immediately when NAT changes are detected, then communication continuity is maintained, but additional signaling overhead and processing load increase
Solution Approach 1:
The patent implements feedback-based update triggering where IPsec tunnel parameters are only updated when actual NAT mapping changes are detected through monitoring. This event-driven approach avoids unnecessary updates during stable conditions, reducing signaling overhead while ensuring updates occur precisely when needed to maintain tunnel validity.
Solution Approach 2:
The patent applies self-service by enabling the UE to autonomously detect NAT changes and trigger its own IPsec tunnel parameter updates without requiring external network intervention. The UE monitors its own communication status and self-corrects tunnel parameters, reducing network signaling load while maintaining tunnel validity.
Data Source
AI summary
A method for maintaining mobile communication continuity, executed by a mobile communications device. The method includes: starting a timer when the mobile communications device receives a service packet from or transmits a service packet to a network; and detecting whether the network is reachable and whether a network address translation (NAT) mapping has changed when the mobile communications device does not receive a specific packet and the timer expires.