Appropriate buffer sizes for Internet nodal devices: A networks' topologies–based solution

Abstract

Summary Switched networks' (including the Internet) nodal devices require buffers to hold packets during periods of congestion and when traffic streams on more than one input port need to access the same output port. Appropriately sizing the buffers has been a contentious issue among researchers over the last couple of years. Three main buffer sizing formulas have been reported in literature, which are: bandwidth‐delay product or BDP, small buffer, and the tiny buffer formulas. But researchers are largely agreed that the BDP formula results in unrealistically large and wasteful buffers, while a number of researchers have held with good reasons, that the small and tiny buffer formulas are theoretical formulations that cannot be generally and practically applied to real networks. Some researchers have even asserted that deriving a single, universal formula for sizing buffers may not be possible. The main purpose of this paper is to explain an approach, which we term “network topology point –of –view,” that we developed to derive a novel, empirical, generic, practical, easy‐to‐apply, closed‐form formula that can be used to obtain the buffer capacity that is optimal—in terms of the minimum capacity possible for lossless operation, for any switched network node, including nodes (switches and routers) in the Internet. The results obtained from utilizing the formula to specify typical nodal buffers' capacities are largely in agreement with the values of the tiny buffer formula in literature; but this paper's formula additionally specifies what we term “very tiny buffers.” The simple approach adopted for presenting this paper makes it a handy tutorial material that explains this “network topology point‐of‐view” concept.