Dynamic TCP ACK Filtering for High-Latency Networks
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Solution Overview
Problem
Existing TCP ACK filtering methods can be too aggressive, leading to harmful effects such as increased latency and delayed data packet transmission, especially in high-latency networks like those using the DOCSIS standard, where lost data packets cause clients to wait for missing packets and delay ACK packets, exacerbating end-to-end network latency.
Innovation Solution
A dynamic ACK filtering system that adjusts filtering parameters, such as NumPromotions and MaxPromotions, to promote ACK packets only when necessary, allowing for minimal filtering during session startup and increasing aggressiveness as session throughput grows, thereby minimizing harmful effects while maintaining bandwidth efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If aggressive ACK filtering is applied to eliminate unnecessary ACK packets, then bandwidth consumption is reduced and packet processing is simplified, but latency increases and data packet transmission is delayed
Solution Approach 1:
The patent implements dynamic ACK filtering by adjusting the filtering threshold based on current network conditions and latency measurements. The system transitions from static to dynamic filtering behavior, adapting the aggressiveness of ACK elimination to match real-time network state, thereby resolving the contradiction between bandwidth efficiency and latency performance
Solution Approach 2:
The system changes the parameter of ACK filtering aggressiveness based on measured latency and network conditions. By modifying filtering parameters dynamically rather than using fixed rules, the system optimizes the balance between reducing ACK packet overhead and maintaining timely data transmission pacing
2Productivity
If ACK packets are sent frequently to maintain TCP stream pacing, then data packet transmission is maintained, but bandwidth is consumed and network overhead increases
Solution Approach 1:
The patent employs feedback mechanisms where the system monitors network latency, ACK packet intervals, and data transmission rates. Based on this feedback, the dynamic filtering algorithm adjusts its behavior to maintain optimal TCP pacing while adapting ACK packet volume to actual network conditions, resolving the contradiction between maintaining productivity and reducing packet quantity
Data Source
AI summary
A system and method for adjusting the filtering of acknowledgments (ACKS) in a TCP environment. State variables are used to keep track of, first, the number of times an ACK has been promoted into (a variable which can be stored on a per-packet basis along with the session ID), and second, the number of times an ACK is allowed to be promoted into (which can be global, or can be stored per-session).