Economics of buffer space provisioning in data communication systems

In data communication systems, system designers often face the quintessential dilemma of how much buffer space for storing packet or cell data is to be provided to satisfy performance requirements cost effectively. The dilemma is created by the pitfalls associated with the over-provisioning and the under-provisioning of buffer space. Over-provisioning of buffer space triggers increased system cost in terms of board space and the price of the total solution. Under-provisioning, on the other hand, triggers instability of the system leading to performance degradation causing eventual system failure. The performance degradation manifests itself in packet or cell drops potentially triggering increased number of re-transmissions at the higher layers which is detrimental to the network goodput altogether. Thus, finding an optimal operating point in the buffer-space/line-rate plane is critical to the operation of the system while producing a cost-effective solution. The paper analyzes the theoretical and practical aspects involved in sizing buffer space in general terms.