Bandwidth dimensioning in packet-based aggregation networks

Dimensioning of link capacities in packet networks in most cases is based on average traffic and some degree of over-provisioning. While mean traffic load is well understood and measurable, the appropriate degree of over-provisioning is a matter of guess and sometimes controversial disputes among experts. We show that traffic fluctuations around the mean value— and in consequence the required over-provisioning— are decisively influenced by the end user access capacity. A theoretical analysis of flow inter-arrival time and flow length probability distributions is used to derive a practical dimensioning rule for packet links in aggregation networks (LAN as well as WAN). The theory has been cross checked by real life experiments with real network equipment.