The Uniformization Process of the Fast Congestion Notification (FN)

TL;DR

This paper analyzes how the Fast Congestion Notification (FN) mechanism uses a uniformization process to control queue size, prevent congestion, and reduce synchronization issues by regulating packet marking intervals.

Contribution

It introduces a uniformization process for FN that improves congestion avoidance and control by regularizing packet marking intervals, enhancing overall network stability.

Findings

FN effectively controls queue size and congestion.

Uniformization reduces global synchronization.

Improved stability and performance of FN.

Abstract

Fast Congestion Notification (FN) is one of the proactive queue management mechanisms that practices congestion avoidance to help avoid the beginning of congestion by marking or dropping packets before the routers queue gets full; and exercises congestion control, when congestion avoidance fails, by increasing the rate of packet marking or dropping. Technically, FN avoids the queue overflows by controlling the instantaneous queue size below the optimal queue size, and control congestion by keeping the average arrival rate close to the outgoing link capacity. Upon arrival of each packet, FN uses the instantaneous queue size and the average arrival rate to calculate the packet marking or dropping probability. FN marks or drops packets at fairly regular intervals to avoid long intermarking intervals and clustered packet marks or drops. Too many marked or dropped packets close together can cause global synchronization, and also too long packet intermarking times between marked or dropped packets can cause large queue sizes and congestion. This paper shows how FN controls the queue size, avoids congestion, and reduces global synchronization by uniformizing marked or dropped packet intervals.