Kathleen S. Meier-Hellstern

The Markov-modulated Poisson process (MMPP) cookbook

Abstract Point processes whose arrival rates vary randomly over time arise in many applications of interest, notably in communications modeling. The Markov-modulated Poisson process has been extensively used for modeling these processes, because it qualitatively models the time-varying arrival rate and captures some of the important correlations between the interarrival times while still remaining analytically tractable. The purpose of this paper is to collect a number of useful results about Markov-modulated Poisson processes and queues with Markov-modulated input. It is intended for non-experts or for people who are familiar with the basic concepts and algorithms, but would like a summary of recent developments. Derivations and proofs have been intentionally omitted. They can be found in the publications listed at the end of each section. Many of the results and some of the text have been taken directly from the references, and the reader is encouraged to consult the relevant references for more detailed information.

The analysis of a queue arising in overflow models

A methodology is presented for analyzing a queuing submodel which frequently arises in the study of overflow models. In this submodel a finite capacity, multiserver queue with exponentially distributed service times, and arriving traffic consisting of a Poisson parcel and several overflow parcels, are assumed. By modeling the overflow parcels as interrupted Poisson processes, an exact queuing analysis is possible. The analysis yields the steady-state queue length distribution, and for each input parcel: (1) the steady-state queue length distribution at arrivals; (2) the probability that an arriving call is blocked (parcel blocking); and (3) the waiting time distribution of an arriving call, in addition to a complete characterization of the overflow due to each parcel. >

Network control for wireless communications

Existing wireless network architectures and the increasing demand for cellular services are reviewed. Wireless network control tasks and the structure of a cellular packet switch (CPS) based on an optical fiber metropolitan area network (MAN) are described. Protocols for moving information through the MAN focusing on handoff, a crucial function of wireless networks, are discussed. The results of an analysis of switch performance as measured by capacity and the distribution of functionality are presented. Several open issues regarding the capability of the CPS to deliver telephone service to wireless terminals, including privacy and security issues, are discussed.<<ETX>>

NIS04-2: Detection of DNS Anomalies using Flow Data Analysis

The Domain Name System (DNS) is an essential network infrastructure component since it supports the operation of the Web, Email, Voice over IP (VoIP) and other business- critical applications running over the network. Events that compromise the security of DNS can have a significant impact on the Internet since they can affect its availability and its intended operation. This paper describes algorithms used to monitor and detect certain types of attacks to the DNS infrastructure using flow data. Our methodology is based on algorithms that do not rely on known signature attack vectors. The effectiveness of our solution is illustrated with real and simulated traffic examples. In one example, we were able to detect a tunneling attack well before the appearance of public reports of it.

Efficient routing of information between interconnected cellular mobile switching centers

At the switch boundaries of cellular systems, it is necessary to provide an inter-switch handover procedure if calls are to remain in progress as users cross these boundaries. Both the North American and Pan European second generation standards provide mechanisms for inter-switch handover. Motivated by the need to develop procedures for inter-switch handover in the cellular packet switch (CPS), this paper develops a general set of procedures for inter-switch handover that, unlike their second generation counterparts, provide a mechanism for the transport of data. Unlike voice, data packets must all be delivered. The delivery may need to be sequential and/or restricted to a single copy. The path optimization procedures are all presented in the context of the CPS. In addition, we identify capabilities needed by the CPS and present suitable protocols. The path optimization procedures are evaluated based on the following performance criteria: guarantee of sequential delivery, avoidance of multiple copies, and delay. Fundamental limitations on data throughput result if both sequential delivery and a single copy are required.

Packet switch engineering procedures when customer characteristics are uncertain

A method for packet-switch provisioning which accounts for the effects of uncertainty in estimating customer characteristics is demonstrated. The method models the traffic parameters of the customers as random variables. It is used to calculate the maximum number of customers that can be accommodated while controlling the probability that their traffic control is beyond the nominal capacity of the system. It is shown that, depending on the degree of uncertainty in estimating parameters for the arrival process, the application of the method can have a substantial impact on the provisioning of the switch. Examples in which the effects of uncertainty on engineering are quantified are given. >

Traffic models for ISDN and B-ISDN users

ISDN, so many years in the making, with its promise of new and exciting applications and services is now a reality. In the teletraffic world we are off conquering new and exciting fields including that of Broadband ISDN (BISDN). However, before leaving narrowband ISDN completely behind, it may be worthwhile to more fully explore this realm where theories, at least to some extent, can be tested against measured data and insights into future needs can be gained.