Perspectives on router buffer sizing

Abstract

The past few years have witnessed a lot of debate on how large Internet router buffers should be. The widely believed rule-ofthumb used by router manufacturers today mandates a buffer size equal to the delay-bandwidth product. This rule was first challenged by researchers in 2004 who argued that if there are a large number of long-lived TCP connections flowing through a router, then the buffer size needed is equal to the delaybandwidth product divided by the square root of the number of long-lived TCP flows. The publication of this result has since reinvigorated interest in the buffer sizing problem with numerous other papers exploring this topic in further detailranging from papers questioning the applicability of this result to proposing alternate schemes to developing new congestion control algorithms, etc.This paper provides a synopsis of the recently proposed buffer sizing strategies and broadly classifies them according to their desired objective: link utilisation, and per-flow performance. We discuss the pros and cons of these different approaches. These prior works study buffer sizing purely in the context of TCP. Subsequently, we present arguments that take into account both real-time and TCP traffic. We also report on the performance studies of various high-speed TCP variants and experimental results for networks with limited buffers. We conclude this paper by outlining some interesting avenues for further research.

A Novel Scheme for Dynamic Triggering Of Packet Dispersion

“…We must point out that careful queue capacity [7]- [10] and packet dispersion threshold selection must be made. As it was previously stated, it is not recommended to trigger packet dispersion frequently.…”

The Effect of the Buffer Size in QoS for Multimedia and Bursty Traffic: When an Upgrade Becomes a Downgrade

“…This traffic profile may produce some uncertainty in buffer sizing, since a small buffer will increase packet loss but a big one will excessively delay real-time packets. In [10] and [4], combined TCP and UDP traffic flows were tested in very small buffers using non-bursty traffic, and an anomalous region was found where the probability of loss of UDP packets grows when the buffer size increases.…”

“…As a consequence, the influence of the buffer should be considered when trying to improve link utilization. Many studies related to buffer size issues have been published in recent years, but they are mainly focused on backbone routers and TCP flows [4] and not on buffer behaviour.…”

Explicit feedback for congestion control in Science DMZ cyberinfrastructures based on programable data-plane switches.

“…[98] incorporated this observation and proved that for N desynchronized flows, the bottleneck link could be kept fully utilized with a buffer size of approximately C •RT T / √ N . Note that this new rule assumes that flows use long-lived TCP New Reno congestion control [99], which is based on the additive increase multiplicative decrease (AIMD) behavior. Thus, it does not apply to new congestion control algorithms based on pacing, such as BBR [100] and BBRv2 [101].…”