TTL-Based Keep-Alive Routing for Mobile Connection Maintenance
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Solution Overview
Problem
Current mobile communications systems face challenges in maintaining open connections through internet firewalls and network address translators (NATs) due to timeouts, leading to excessive battery drainage and resource wastage, as existing methods for keeping connections alive, such as heartbeat messages, require terminals to constantly wake up and respond, consuming energy and resources.
Innovation Solution
A method is introduced where a data packet with a time-to-live (TTL) is sent through a packet data network to maintain traffic and keep connections open by routing it through intervening network entities without reaching the terminal, allowing the terminal to idle and reducing power consumption by avoiding unnecessary traffic and resource usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If heartbeat messages are sent at high rate to prevent connection timeout, then connection reliability is improved, but battery life deteriorates due to excessive terminal wake-ups and transmissions
Solution Approach 1:
An adaptation element is introduced as an intermediary between the host and terminal. This element receives heartbeat data packets from the host, adjusts their TTL values to prevent delivery to the terminal, and forwards modified packets or acknowledgments back to the host. The terminal remains in idle mode while the adaptation element maintains the connection by manipulating packet routing, thus resolving the contradiction between connection reliability and battery consumption
Solution Approach 2:
The problematic function of delivering heartbeat packets to the terminal is extracted and relocated to an adaptation element. By removing the terminal from the heartbeat packet delivery path and placing the adaptation element in its place, the terminal is freed from the energy-consuming task of processing heartbeat packets while the connection maintenance function is preserved by the adaptation element
2Reliability
If keep-alive messages are sent from terminal to host, then connection maintenance is improved, but device complexity increases due to additional signaling requirements
Solution Approach 1:
Instead of having the terminal send keep-alive messages to the host (traditional approach), the invention inverts the approach by having the host send heartbeat packets that are intercepted and modified by the adaptation element. The adaptation element sends acknowledgments back to the host, creating a reversed signaling flow that maintains connections without requiring terminal-initiated keep-alive messages, thus reducing terminal complexity
3Duration of action of stationary object
If firewall and NAT timeouts are lengthened to maintain connections, then connection duration is improved, but adaptability deteriorates as not all NATs and firewalls can be controlled
Solution Approach 1:
The adaptation element serves as a mediator that works around the limitations of uncontrollable firewalls and NATs. By intercepting and modifying heartbeat packets before they reach the terminal, and by sending appropriate acknowledgments back through the network path, the adaptation element maintains connections regardless of the timeout settings of intermediate network devices, thus achieving both extended connection duration and broad network compatibility
Data Source
AI summary
A client and a host communicate in a packet data network including a plurality of routing nodes such as routers and firewalls. The host is configured to provide the client with a session and to detect the accessibility of the client by repeatedly sending keep-alive messages to the client. In order to reduce the traffic actually arriving at the client, at least some of the keep-alive message are adjusted such that their routing towards the client will be stopped before the client by storing in a Time-To-Live field specified in the Internet Protocol a value of maximum routing hops defined to correspond with the last routing node before the client on a route from the host to the client. The adaptation of the keep-alive message can also be configured to allow some keep-alive message to reach the client to occasionally test the communication path between the client and server.