Time-Guarded Flow Rule Installation for Scalable Smart City Networks
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Solution Overview
Problem
Flow-based programmable network devices face scalability issues and high signaling loads due to the need for permanent flow rules in Smart City networks with numerous sensors, leading to overload of switch flow tables and control planes, especially in the downlink direction.
Innovation Solution
Implementing a method for just-in-time flow rule installation using a time-trigger module that autonomously activates forwarding rules based on packet flow information, reducing the need for continuous controller interaction and distributing flow table entries over time, thereby enhancing scalability and security.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If permanent flow rules are installed for every sensor, then forwarding reliability is improved, but flow table overload occurs
Solution Approach 1:
The system performs preliminary actions by installing flow rules in advance based on predicted packet transmission times. The controller receives packet flow information including times and intervals of transmission, and programs forwarding rules before the actual packet arrival, allowing the flow rules to be activated just-in-time without requiring permanent entries for all possible sensors.
Solution Approach 2:
The flow table transitions from a static permanent rule structure to a dynamic time-guarded structure. Flow rules are installed and activated at specific times based on packet transmission schedules, and automatically removed after their validity period. This dynamic approach allows the same flow table to serve multiple sensors over time without accumulating permanent entries for all of them simultaneously.
2Quantity of substance
If reactive flow rule installation is used, then flow table overload is reduced, but signaling load increases
Solution Approach 1:
Instead of reacting to actual packet arrivals by installing flow rules on-demand, the system performs preliminary rule installation based on predicted transmission times. The controller receives advance information about when packets will arrive and pre-installs the necessary flow rules, eliminating the need for continuous controller- switch signaling during packet transmission.
Solution Approach 2:
The switch autonomously manages flow rule installation and removal based on time information received from the controller. Rather than requiring continuous controller intervention for each packet flow, the switch uses the received packet flow information (times and intervals) to automatically program and activate flow rules at the appropriate moments, reducing signaling overhead.
3Productivity
If flow rules are activated continuously, then forwarding performance is improved, but network security decreases
Solution Approach 1:
The system installs flow rules in advance based on predicted transmission times, but activates them only when needed. The flow rules are programmed with timeout values that cause them to automatically disappear after a while, ensuring they are active only during the expected packet transmission window rather than continuously, thus limiting security exposure.
Solution Approach 2:
Flow rules are activated periodically based on the transmission schedule of packet-generating devices. Instead of continuous activation, the system uses periodic installation and activation of flow rules at specific times intervals, matching the actual packet transmission pattern. This periodic approach maintains forwarding performance during active periods while maintaining security by keeping rules inactive during non-transmission periods.
Data Source
AI summary
A method for flow rule installation in a flow-based programmable network device, includes obtaining packet flow information that includes information about times and intervals of packet flow transmissions from data transmitting devices, programming, by a controller entity, forwarding rules into a flow table based on the packet flow information, and triggering activation of a forwarding rule programmed for a particular packet flow just-in-time before actual transmission of the particular packet flow. The flow-based programmable network device comprises input/output ports, a flow table including forwarding rules that map packet flows from data transmitting devices in the network, received on an input port, to an output port based on a packet flow matching a rule in the forwarding rules, and a state table including state entries that specify states of the packet flows.