Dropped Packet Capture With Context for Network Loss Analysis
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Solution Overview
Problem
Network devices are unable to provide context about dropped packets, limiting users' understanding of why packets were dropped, such as due to link capacity issues or network device policies.
Innovation Solution
Network devices capture and store information about dropped packets, including their content and identity, and record a predetermined number of preceding and trailing packets, allowing users to understand the cause of packet drops through packet loss events and sequence numbers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If packet loss rate is calculated using only ACK packets, then the calculation is simple, but the measurement is inaccurate when ACK packets are lost
Solution Approach 1:
The patent introduces a dummy ACK packet as an intermediary mechanism. When a data packet is sent, a corresponding dummy ACK is generated and tracked separately. This intermediary allows the system to measure packet loss by comparing sent data packets against their dummy ACK counterparts, rather than relying solely on actual ACK packets from the remote end, thereby improving measurement accuracy while maintaining relatively simple implementation
Solution Approach 2:
The patent creates a copy of the data packet transmission process by generating dummy ACK packets that mirror the expected ACKs. These dummy ACKs are tracked in a separate queue and used as a reference to determine whether data packets were successfully transmitted. This copying approach enables accurate packet loss measurement without depending on the potentially lost actual ACK packets
2Measurement precision
If packet loss rate is calculated using both data packets and ACK packets, then the measurement accuracy improves, but the complexity of tracking and calculating increases
Solution Approach 1:
The patent extracts the packet loss measurement function from the complex dual-tracking system and implements it using only data packet transmission and dummy ACK generation. By separating the measurement mechanism from the actual data communication flow, the system achieves accurate packet loss measurement without the complexity of simultaneously tracking both data packets and real ACK packets from the remote end
Solution Approach 2:
The system performs self-service measurement by generating its own dummy ACK packets and tracking them internally. Rather than relying on external ACK packets from the remote end, the system creates its own reference points (dummy ACKs) and uses these to measure packet loss, thereby simplifying the measurement process while maintaining accuracy
3Reliability
If sequence numbers are not incremented for dummy ACKs, then the implementation is simpler, but packet loss detection becomes unreliable
Solution Approach 1:
The patent applies preliminary action by pre-incrementing the sequence number for each dummy ACK packet before it is sent. This ensures that each dummy ACK has a unique, monotonically increasing sequence number that can be reliably tracked. By performing this sequence number assignment in advance rather than reacting to packet loss events, the system achieves reliable packet loss detection without complex real-time sequence number management
Data Source
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AI summary
Packets in a network may be dropped from time to time. Although network devices are able to provide counters specifying the number of dropped packets, these network devices are unable to provide additional context about the dropped packets. However, users of a network wish to know more about dropped packets; such as why the packets were dropped. Therefore, methods for capturing and storing the dropped packets are provided. This way, users can analyze the dropped packets to determine why these packets were dropped.