Packet Discard Point Probing via Sequence Number Analysis
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Solution Overview
Problem
Current methods for detecting packet discard faults in networks, especially before and after L2 switches or hubs, are inefficient, requiring extensive time, cost, and labor, and often cannot specify the exact discard point, leading to prolonged recovery times and high expenses.
Innovation Solution
A packet discard point probing method that transmits sequential packets across a transmission line with speed changes, detects packet discards by analyzing packet intervals, and determines if the discard occurred in the high-speed or low-speed section, allowing for precise identification of fault locations without the need for numerous hosts or costly equipment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If packet capture probing method is used to specify discard point, then measurement precision is improved, but device complexity and cost increase due to requiring capture devices and multiple hosts
Solution Approach 1:
The invention extracts the essential function of packet capture (sequence number analysis) and implements it using only standard network protocol processing capabilities that exist in ordinary network devices, eliminating the need for specialized capture hardware. By taking out the core measurement function and implementing it through standard IP protocol fields, the system achieves accurate discard point detection without requiring complex additional devices.
Solution Approach 2:
The probing system utilizes the inherent sequence number fields already present in IP packets for its measurement function. Instead of requiring external capture devices to add measurement capabilities, the method makes the existing packet structure serve the probing purpose directly. The sequence numbers embedded in standard IP headers are leveraged to detect discards, making the probing system self-sufficient without external specialized equipment.
2Device complexity
If ping probing method is used to measure discard ratio, then device complexity is reduced, but measurement precision deteriorates because discard points before L2 switches cannot be specified
Solution Approach 1:
The invention segments the network path into multiple sections by analyzing sequence number gaps at different probing points. By dividing the detection into stages (comparing sequence numbers at source and destination), the method can identify which specific segment contains the discard point, enabling precise location of discards even before L2 switches while using only simple ping-like probing mechanisms.
Solution Approach 2:
The invention adds a new dimension of analysis by examining sequence number continuity across the network path rather than relying solely on ICMP ping responses. This dimensional shift from simple connectivity testing to sequence number-based flow analysis enables precise discard point identification while maintaining the simplicity of the probing approach.
3Reliability
If Inverse ARP method is used to confirm frame relay communication, then reliability is improved, but productivity decreases due to extensive setting and measurement time
Solution Approach 1:
The invention performs preliminary probing actions by sending test packets with sequence numbers before actual communication failures occur. This preliminary sequence number-based validation establishes a baseline for detecting discards, enabling faster fault detection and recovery without requiring extensive Inverse ARP setting and measurement procedures when failures actually occur.
Solution Approach 2:
The invention changes the parameter used for communication validation from Inverse ARP response presence to IP packet sequence number continuity. This parameter change enables more efficient discard detection that doesn't require the extensive Inverse ARP configuration and measurement time, thereby improving fault recovery productivity while maintaining reliability.
Data Source
AI summary
In a relay device or the like in which a speed changes from a high speed to a low speed, a packet residence (packet transfer wait) occurs when a packet string in which packet intervals are shortened arrives. When a packet discard occurs before passing through the relay device or the like, a packet interval having been lengthened by the packet discard is shortened by the relay device or the like for transferring packets. When a packet discard occurs after passing through the relay device or the like, a packet interval having been lengthened by the packet discard remains unshortened for transferring packets. Therefore, by observing at terminals the packet discard and the packet interval on the occasion of the packet discard, whether the packet discard has occurred in the high speed section or the low speed section is specified.