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&T's 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     

Traffic engineering with traditional IP routing protocols

Traffic engineering involves adapting the routing of traffic to network conditions, with the joint goals of good user performance and efficient use of network resources. We describe an approach to intradomain traffic engineering that works within the existing deployed base of interior gateway protocols, such as Open Shortest Path First and Intermediate System-Intermediate System. We explain how to adapt the configuration of link weights, based on a networkwide view of the traffic and topology within a domain. In addition, we summarize the results of several studies of techniques for optimizing OSPF/IS-IS weights to the prevailing traffic. The article argues that traditional shortest path routing protocols are surprisingly effective for engineering the flow of traffic in large IP networks.     

Automated provisioning of BGP customers

Manual configuration of IP routers is an expensive, time-consuming, and error-prone process. For large Internet service providers, establishing service for new customers is a major part of the financial cost of running the network. Increasingly, these customers want to exchange routing information with their provider(s) using the border gateway protocol (BGP), a complex and highly programmable interdomain routing protocol. This article describes how a provider can configure its connections to BGP-speaking customers, from the technical questions asked of new customers to the individual configuration commands applied to the production routers. We present a case study of a technical questionnaire and describe how the provider assigns unique identifiers such as IP address blocks, interface names, and access control list numbers on behalf of the customer. Next, we describe an example set of provisioning rules that use the customer-specific information to generate a sequence of configuration commands - a "configlet" - for adding the new connection to the network; our configuration rules are expressed using Cisco Internet Operating System (IOS) commands as an example. Then we describe a database schema for storing and accessing the customer-specific data, and discuss how to use a virtual view on this database to populate a template that captures the syntax of the router commands. Our provisioning system provides an inexpensive, efficient, and accurate way for a provider to configure connections to new BGP-speaking customers.     

Scalable architectures for integrated traffic shaping and linkscheduling in high-speed ATM switches

Emerging broad-band switches must accommodate the diverse traffic parameters and quality-of-service requirements of voice, data, and video applications. End-to-end performance guarantees depend on connections complying with traffic contracts as their cells travel through the network. This paper presents a leaky-bucket shaper architecture that scales to a large number of connections with diverse burstiness and bandwidth parameters. In contrast to existing designs, the proposed architecture arbitrates fairly between connections with conforming cells by carefully integrating leaky-bucket traffic shaping with rate-based scheduling algorithms. Through a careful combination of per-connection queueing and approximate sorting, the shaper performs a small, bounded number of operations in response to each arrival and departure, independent of the number of connections and cells. When the shaper must handle a wide range of rate parameters, a hierarchical arbitration scheme can reduce the implementation overheads and further limit interference between competing connections. Through simulation experiments, we demonstrate that the architecture limits cell-shaping delay and traffic distortions, even in periods of heavy congestion. The efficient combination of traffic shaping and link scheduling results in an effective architecture for managing buffer and bandwidth resources in large, high-speed ATM switches     

pp-mess-sim: a flexible and extensible simulator for evaluatingmulticomputer networks

The paper presents pp-mess-sim, an object-oriented discrete-event simulation environment for evaluating interconnection networks in message-passing systems. The simulator provides a toolbox of various network topologies, communication workloads, routing-switching algorithms, and router models. By carefully defining the boundaries between these modules, pp-mess-sim creates a flexible and extensible environment for evaluating different aspects of network design. The simulator models emerging multicomputer networks that can support multiple routing and switching schemes simultaneously; pp-mess-sim achieves this flexibility by associating routing-switching policies, traffic patterns, and performance metrics with collections of packets, instead of the underlying router model. Besides providing a general framework for evaluating router architectures, pp-mess-sim includes a cycle-level model of the PRC, a programmable router for point-to-point distributed systems. The PRC model captures low-level implementation details, while another high-level model facilitates experimentation with general router design issues. Sample simulation experiments capitalize on this flexibility to compare network architectures under various application workloads     

Risking Communications Security: Potential Hazards of the Protect America Act

A new US law allows warrantless wiretapping whenever one end of the communication is believed to be outside national borders. This creates serious security risks: danger of exploitation of the system by unauthorized users, danger of criminal misuse by trusted insiders, and danger of misuse by government agents.