Network Device Egress Rate Marking for Congestion Control
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Solution Overview
Problem
Conventional network devices rely on buffer threshold detection for Explicit Congestion Notification (ECN) marking, leading to increased latency and potential packet dropping due to delayed congestion mitigation, especially in long round trip times, necessitating larger buffer sizes to absorb congestion until source devices reduce transmission rates.
Innovation Solution
A network device measures link utilization to determine when to employ congestion control techniques like ECN marking, allowing for earlier initiation of congestion control before buffer thresholds are reached, thereby reducing latency and packet dropping without requiring large buffer increases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If buffer threshold detection is used for ECN marking, then packet marking is triggered, but latency increases and packet dropping occurs due to delayed congestion mitigation
Solution Approach 1:
The patent applies preliminary action by measuring link utilization rates continuously and initiating ECN marking before buffer thresholds are reached. The system proactively detects congestion trends through egress rate monitoring and starts packet marking when utilization exceeds a threshold, rather than waiting for buffer fill level thresholds. This early intervention prevents buffer overflow and reduces latency by initiating congestion control before packets start dropping.
2Reliability
If buffer size is increased to absorb congestion, then packet dropping is reduced, but device cost increases
Solution Approach 1:
The patent implements feedback by continuously measuring egress rates and using this information to dynamically control ECN marking. The system monitors link utilization rates and adjusts packet marking based on real-time congestion conditions. This feedback mechanism allows the system to maintain appropriate buffer sizes while effectively managing congestion through intelligent packet marking, avoiding the need for excessively large buffers.
3Productivity
If ECN marking is initiated at buffer threshold, then congestion control is triggered, but the delay between marking and source rate reduction increases
Solution Approach 1:
The patent applies preliminary action by measuring link utilization rates and initiating ECN marking before buffer thresholds are reached. The system proactively detects congestion trends through egress rate monitoring and starts packet marking when utilization exceeds a threshold, rather than waiting for buffer fill level thresholds. This early intervention reduces the time between congestion detection and source rate reduction, improving congestion control effectiveness.
Data Source
AI summary
A network device includes a rate measurement circuit that is configured to measure respective egress rates at which respective data is being transmitted via respective ports associated with the network device. A marking ratio determination circuit is configured to select respective marking ratios based on respective measured egress rates, the marking ratios for marking packets to be transmitted via the respective ports to indicate respective levels of congestion corresponding to the respective ports. Different marking ratios correspond to different measured egress rates. A packet editor circuit is configured to mark selected packets to be transmitted via respective ports according to the respective selected marking ratios. The respective selected marking ratios indicate to other communication devices that respective network paths via which the selected packets travelled experienced congestion, and the respective marking ratios indicate respective levels of congestion.