Packet Forwarding Apparatus Flow End Detection Rule Deletion
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Solution Overview
Problem
In OpenFlow systems, process rules remain in the flow table even after communication ends, leading to inefficient storage usage and rule matching, as they are not accurately deleted, causing unnecessary storage occupation and decreased efficiency.
Innovation Solution
A packet forwarding apparatus with a process rule storage unit, packet process unit, end determination information extraction unit, and flow end check unit that extracts information from received packets to determine the end of a flow and delete corresponding process rules, using methods like TCP FIN flags, timeouts, or HTTP Close attributes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If process rules are retained in the flow table for a fixed expiration time after communication ends, then storage stability is maintained, but storage space is wasted and rule matching efficiency decreases
Solution Approach 1:
The patent applies the Dynamics principle by transitioning from a static, time-based rule retention mechanism to a dynamic, event-driven deletion mechanism. Instead of retaining all process rules for a fixed expiration time regardless of communication status, the system dynamically monitors communication states through TCP flags (FIN, RST) and HTTP attributes (Connection: close) to determine when to delete rules. This dynamic approach ensures rules are retained only as long as needed for active communications while being promptly removed when communication ends, thereby maintaining storage stability for active rules while improving rule matching efficiency by eliminating stale rules.
2Quantity of substance
If process rules are deleted based on idle timeout, then storage space is recovered, but necessary rules may be incorrectly deleted
Solution Approach 1:
The patent applies the Feedback principle by implementing a communication state monitoring mechanism that continuously observes TCP flags and HTTP attributes to provide feedback on whether a process rule is still needed. Instead of blindly deleting rules after a fixed idle timeout, the system receives feedback from communication state indicators (such as FIN flag indicating connection termination, RST flag indicating reset, or HTTP Connection: close attribute) to make informed deletion decisions. This feedback-driven approach ensures storage space is recovered from truly inactive rules while preventing incorrect deletion of rules that may appear idle but are still actively used.
3Quantity of substance
If the flow table size is increased to accommodate more process rules, then rule storage capacity is improved, but memory usage increases
Solution Approach 1:
The patent applies the Discarding and recovering principle by systematically identifying and deleting process rules that are no longer needed based on communication state monitoring. Instead of simply increasing flow table size to accommodate growing numbers of rules, the system actively discards stale rules by monitoring for communication termination indicators (TCP FIN/RST flags, HTTP Connection: close attributes) and promptly removing corresponding process rules. This recovery of storage capacity allows the system to maintain efficient memory usage while providing sufficient storage capacity for active communications, as space is continuously reclaimed from inactive rules.
Data Source
AI summary
A packet forwarding apparatus, a communication system, and a process rule update method that can accurately delete process rules used for packet forwarding and the like include a process rule storage unit that stores process rules defining a process content for each flow; a packet process unit that executes processing a received a packet by using a process rule matching the received packet among the process rules and; an end determination information extraction unit that extracts information for checking a flow end from the received packet; and a flow end check unit that deletes, when a flow end is checked based on the extracted information, a process rule corresponding to the flow.