Network Element NACK Notification for Packet Drop Latency
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Solution Overview
Problem
Current TCP protocols experience long latency in retransmitting packets due to timer-based acknowledgement schemes, leading to reduced effective bandwidth in networks, especially when packet drops occur due to congestion or corruption.
Innovation Solution
Implementing a NACK (Negative ACKnowledgement) packet system where network elements detect dropped packets and immediately notify the source, allowing for immediate retransmission without waiting for the retransmission timeout timer to expire, and augmenting TCP socket logic to process NACK packets and retransmit dropped packets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If timer-based acknowledgement schemes are used in TCP protocols, then reliability of data transmission is maintained, but latency in retransmitting dropped packets increases
Solution Approach 1:
The patent implements preliminary action by having network elements proactively send Negative Acknowledgement (NACK) packets to notify sources of dropped packets before the retransmission timeout period expires. This allows the source to immediately retransmit the dropped packet without waiting for the timer to expire, thereby reducing retransmission latency while maintaining the reliability benefits of TCP's timer-based acknowledgment scheme.
2Reliability
If retransmission timeout timers are used to ensure reliable delivery, then data integrity is preserved, but bandwidth utilization decreases due to waiting periods
Solution Approach 1:
The patent applies feedback by implementing a NACK mechanism where network elements provide immediate feedback to sources about dropped packets. When a network element detects a dropped packet, it sends a NACK packet to the source, which triggers immediate retransmission. This feedback loop eliminates the passive waiting period associated with timeout timers, improving bandwidth utilization while preserving data delivery reliability through confirmed retransmission.
3Adaptability or versatility
If conventional TCP acknowledgement mechanisms are employed, then protocol compatibility is maintained, but retransmission speed is reduced due to timeout waiting
Solution Approach 1:
The patent introduces an intermediary mechanism in the form of NACK packets that facilitate faster retransmission without disrupting conventional TCP operation. The NACK mechanism acts as an intermediary layer between the standard TCP acknowledgment process and the retransmission action, allowing sources to retransmit dropped packets immediately upon receiving NACK notifications while maintaining compatibility with existing TCP protocols and infrastructure.
Data Source
AI summary
Methods and apparatus for implementing notification by network elements of packet drops. In response to determining a packet is to be dropped, a network element such as a switch or router determines the source of the packet and returns a dropped packet notification message to the source. Upon receipt of notification, networking software or embedded hardware on the source causes the dropped packet to be retransmitted. The notification may also be sent from the network element to the destination computer to inform networking software or embedded logic implemented by the destination computer that the packet was dropped and notification to the source has been sent, thus alleviating the destination from needing to send a Selective ACKnowledge (SACK) message to inform the source the packet was not delivered. (Too narrow)