Charles Robert Kalmanek

Rate controlled servers for very high-speed networks

Future high-speed networks are expected to carry traffic with a wide range of performance requirements. Two queue service disciplines, rate-based scheduling and hierarchical round robin scheduling, are described. These disciplines allow some connections to receive guaranteed rate and jitter performance, while others receive best-effort service. Rate based scheduling is designed for fast packet networks, while hierarchical round robin is an extension of round robin scheduling suitable for use in networks based on the asynchronous transfer mode (ATM) being defined in CCITT. Both schemes are feasible at rates of 1 Gb/s. The schemes allow strict bounds on the buffer space required for rate controlled connections and can provide efficient utilization of transmission bandwidth.<<ETX>>

Efficient distributed path selection for shared restoration connections

In MPLS/GMPLS networks, a range of restoration schemes are required to support different tradeoffs between service interruption time and network resource utilization. In light of these tradeoffs, path-based, end-to-end shared restoration provides a very attractive solution. However, efficient use of capacity for shared restoration strongly relies on the selection procedure of restoration paths. We propose an efficient path-selection algorithm for restoration of connections over shared bandwidth in a fully distributed GMPLS architecture. We also describe how to extend GMPLS signaling protocols to collect the necessary information efficiently. To evaluate the algorithms performance, we compare it via simulation with two other well-known algorithm on a typical intercity backbone network. The key figure-of-merit for restoration capacity efficiency is restoration overbuild, i.e., the extra capacity required to meet the network restoration objective as a percentage of the capacity of the network with no restoration. Our simulation results show that our algorithm uses significantly less restoration overbuild (63-68%) compared to the other two algorithms (83-90%).

Measurement and analysis of IP network usage and behavior

Traffic, usage, and performance measurements are crucial to the design, operation and control of Internet protocol networks. This article describes a prototype infrastructure for the measurement, storage, and correlation of network data of different types and origins from AT&Ts commercial IP network. We focus first on some novel aspects of the measurement infrastructure, then describe analyses that illustrate the power of joining different measured data sets for network planning and design.

Control plane design for reliable optical networks

The application of an IP-based control plane to optical networks has opened up new opportunities and challenges for network designers. Although much work has been done on standardization of protocols for IP networks, the applicability of these protocols to controlling optical networks and the overall reliability of optical networks needs further investigation. This article provides a detailed discussion of a number of subtle protocol design and implementation issues that were not addressed in early standardization efforts or published papers.

Efficient distributed restoration path selection for shared mesh restoration

In MPLS/GMPLS networks, a range of restoration schemes will be required to support different tradeoffs between service interruption time and network resource utilization. In light of these tradeoffs, path-based end-to-end shared mesh restoration provides a very attractive solution. However, efficient use of bandwidth for shared mesh restoration strongly relies on the procedure for selecting restoration paths. In this paper, we propose an efficient restoration path selection algorithm for restorable connections over shared bandwidth in a fully distributed MPLS/GMPLS architecture. We also describe how to extend MPLS/GMPLS signaling protocols to collect the necessary information efficiently. To evaluate the algorithms performance, we compare it via simulation with two other well-known algorithms on a typical intercity backbone network. The key figure of merit for restoration bandwidth efficiency is restoration overbuild, i.e., the extra bandwidth required to meet the network restoration objective as a percentage of the bandwidth of the network with no restoration. Our simulation results show that our algorithm uses significantly less restoration overbuild (63%-68%) compared with the other two algorithms (83%-90%).

A Network Based Replay Portal

A network based video replay service utilizing broadband technologies on the internet. A replacement for current analog or digital TV offerings that offer the same quality and user experience. The capacity used by current offerings (e.g. on a cable access network) will be freed up for use by the new service. The current schedule based broadcast paradigm users are accustomed to is emulated while at the same time offering on-demand viewing based on personal preference or subscription profile. This hybrid offering can lead to bandwidth savings in the access network with interaction of this service with other services on a common packet based infrastructure.

Analysis of communities of interest in data networks

Communities of interest (COI) have been applied in a variety of environments ranging from characterizing the online buying behavior of individuals to detecting fraud in telephone networks. The common thread among these applications is that the historical COI of an individual can be used to predict future behavior as well as the behavior of other members of the COI. It would clearly be beneficial if COIs can be used in the same manner to characterize and predict the behavior of hosts within a data network. In this paper, we introduce a methodology for evaluating various aspects of COIs of hosts within an IP network. In the context of this study, we broadly define a COI as a collection of interacting hosts. We apply our methodology using data collected from a large enterprise network over a eleven week period. First, we study the distributions and stability of the size of COIs. Second, we evaluate multiple heuristics to determine a stable core set of COIs and determine the stability of these sets over time. Third, we evaluate how much of the communication is not captured by these core COI sets.

TOPS: an architecture for telephony over packet networks

Packet telephony is of increasing interest in both the telecommunications and Internet communities. The emergence of packet telephony will create new services, and presents an opportunity to rethink how conventional telephony services are implemented. In this paper, we present an architecture for telephony over packet networks (TOPS). TOPS allows users to move between terminals or to use mobile terminals while being reachable by the same name. TOPS users can have multiple terminals and control how calls are routed to them. TOPS allows for terminals with a range of capabilities such as support for video, whiteboard, and other media with a variety of coding formats. TOPS retains the necessary information on terminal capabilities to determine the appropriate type of communication to be established with the remote terminal. The architecture assumes that the underlying network supports the establishment of end-to-end connectivity between terminals, with an appropriate quality of service. The components of TOPS are a directory service, an application layer signaling protocol, and a logical channel abstraction for communication between end-systems. The directory service maps a users name to a set of terminals where the user may be reached. A user can control the translation operation by specifying profiles that customize how his name is mapped to a set of terminals where he can be reached. Terminal capabilities are also stored in the directory service. The application layer signaling protocol establishes and maintains call state between communicating terminals. The logical channel abstraction provides a shared end-to-end context for a calls constituent media and control streams, while isolating the applications from the details of the network transport mechanisms. In addition to supporting simple point-to-point calls, the architecture supports both centralized and decentralized conferencing. We also introduce a simple encapsulation format for voice.

Experience in measuring internet backbone traffic variability: Models metrics, measurements and meaning

Understanding the variability of Internet traffic in backbo ne networks is essential to better plan and manage existing networks, as well as to design next generati on networks. However, most traffic analyses that might be used to approach this problem are based on detai led packet or flow level measurements, which are usually not available throughout a large network. As a result there is a poor understanding of backbone traffic variability, and its impact on network oper ations (e.g. on capacity planning or traffic engineering). This paper introduces a metric for measuring backbone traffic variability that is grounded on simple but powerful traffic theory. What sets this metric a part, however, is that we present a method for practical implementation of the metric using widely availa ble SNMP traffic measurements. In addition to simulations, we use a large set of SNMP data from an operati onal IP network on the order of 1000 nodes to test our methods. We also delve into the degree and so urce of variability in real backbone traffic, providing insight into the true nature of traffic var i bility.

Darkstar: Using exploratory data mining to raise the bar on network reliability and performance

Networks have become a critical infrastructure, and performance requirements for network-based applications are becoming increasingly stringent. This trend challenges service providers to raise the bar on the performance and reliability of network services. To achieve this, new network and service management systems are needed that enable providers to continually improve performance, identify issues that are flying under the radar of network operations, and troubleshoot complex issues. This paper presents the Darkstar system, which allows analysts to address these challenges using exploratory data mining and sophisticated correlation tools. We present an overview of key applications that are built on top of the Darkstar system to illustrate the power of the approach.