Lightweight link dimensioning using sFlow sampling

Abstract

Operators use link dimensioning to provision network links. In practice, traffic averages are obtained via SNMP are used to roughly estimate required capacity. More accurate solutions often require traffic statistics easily obtained from packet captures, e.g. variance. However, packet capturing may not be trivial in high-speed links. Aiming scalability, operators often deploy packet sampling on monitoring, but little is known how it affects link dimensioning. In this paper we assess the feasibility of lightweight link dimensioning using sFlow, which is a widely-deployed traffic monitoring tool. We implement sFlow sampling algorithm and use a previously proposed and validated dimensioning formula that needs traffic variance.We validate our approach using packet captures from real networks. Results show that the proposed procedure is successful for a range of sampling rates and that, due to randomness of sampling algorithm, the error introduced by scaling the traffic variance yields more conservative results that cope with short-term traffic fluctuations.