Dinesh C. Verma

ALMI: an application level multicast infrastructure

The IP multicast model allows scalable and efficient multi-party communication, particularly for groups of large size. However, deployment of IP multicast requires substantial infrastructure modifications and is hampered by a host of unresolved open problems. To circumvent this situation, we have designed and implemented ALMI, and application level group communication middleware, which allows accelerated application deployment and simplified network configuration, without the need of network infrastructure support. ALMI is tailored toward support of multicast groups of relatively small size (several 10s of members) with many to many semantics. Session participants are connected via a virtual multicast tree, which consists of unicast connections between end hosts and is formed as a minimum spanning tree (MST) using application-specific performance metric. Using simulation, we show that the performance penalties, introducted by this shift of multicast to end systems, is a relatively small increase in traffic load and that ALMI multicast trees approach the efficiency of IP multicast trees. We have also implemented ALMI as a Java based middleware package and performed experiments over the Internet. Experimental results show that ALMI is able to cope with network dynamics and keep the multicast tree efficient.

Simplifying network administration using policy-based management

The management of network infrastructure in an enterprise is a complex and. daunting affair. In an era of increasing technical cornplexity, it is becoming difficult to find trained personnel who can manage the new features introduced into the various servers, routers, and switches. Policy-based network management provides a means by which the administration process can be simplified and largely automated. In this article we look at a general policy-based architecture that can be used to simplify several new technologies emerging in the context of IP networks. We explain how network administration can be simplified by defining two levels of policies, a business level and a technology level. We discuss how business-level policies are validated and transformed into technology-level policies, and present some algorithms that can be used to check for policy conflicts and unreachable policies. We then show how to apply this architecture to two areas: managing performance service level agreements, and supporting enterprise extranets using IPSec communication.

The Tenet real-time protocol suite: design, implementation, and experiences

Many future applications will require guarantees on network performance, such as bounds on throughput, delay, delay jitter, and reliability. To address this need, the authors have designed, simulated, and implemented a suite of network protocols to support real-time channels (network connections with mathematically provable performance guarantees). The protocols, which constitute the prototype Tenet real-time protocol suite (Suite 1), run on a packet-switching internetwork and can coexist with the popular Internet protocol suite. The authors rely on the use of connection-oriented communication, per-channel admission control, channel rate control, and priority scheduling. This protocol suite is the first set of transport and network-layer communication protocols that can transfer real-time streams with guaranteed quality in packet-switching internetworks. The authors have performed a number of experiments and demonstrations on multiple platforms using continuous-media loads (particularly video). The results show that the approach is both feasible and practical to build, and that it can successfully provide performance guarantees to real-time applications. The paper describes the design and implementation of, the suite, the experiments performed, and some of the lessons learned.

A policy framework for integrated and differentiated services in the Internet

We examine the issues that arise in the definition, deployment, and management of policies related to QoS in an IP network. The article provides an overview of requirements for QoS policies, alternative policy architectures that can be deployed in a network, different protocols that can be used to exchange policy information, and exchange of policy information among different administrative domains. We discuss current issues being examined in IETF and other standards bodies, as well as issues explored in ongoing policy-related research at different universities and research laboratories.

Service level agreements on IP networks

This paper provides an overview of service level agreements (SLAs) in IP networks. It looks at the typical components of an SLA and identifies three common approaches that are used to satisfy SLAs in IP networks. The implications of using the approaches in the context of a network service provider, a hosting service provider, and an enterprise are examined. While most providers currently offer a static insurance approach toward supporting SLAs, the schemes that can lead to more dynamic approaches are identified.

Policy transformation techniques in policy-based systems management

Policy based systems management provides a means for administrators, end-users and application developers to manage and dynamically change the behavior of computing systems. One advantage of policy-based management is that it simplifies and automates the administration of IT environments. A significant part of the simplification is obtained by allowing the system administrator to specify only the objectives or goals that are to be met, rather than having to specify detailed configuration parameters for each of the different devices in the system. It may not be obvious to the administrator how the goals can be achieved without having to know the internals of the system. This knowledge thus needs to be captured in the policy driven actions. The existing algorithms for mapping policy objectives to specific configuration details tend to be specific to each policy discipline. This makes the policy-based approach harder to deploy for new disciplines. In this paper, we address different types of policy transformations and propose methods, which are not discipline specific for mapping objectives to system configurations.

Policy-based management of content distribution networks

We present a policy-based architecture for the control and management of content distribution networks that form an overlay of caching proxies over an underlying physical network. The architecture extends the policy framework used for controlling network quality of service (QoS) and security to content distribution networks. The fundamental advantage of a policy-based framework is that it allows a machine-independent scheme for managing multiple devices from a single point of control. In this article we describe this architecture and demonstrate how it enables dynamic updates to content distribution policies. Furthermore, we analyze the impact of such dynamic distribution on the cost of content serving.

Policy Based SLA Management in Enterprise Networks

The Differentiated Services Architecture defines the mechanisms that are needed to offer multiple classes of services in an IP network. While this model offers significant scaling advantages over the signaling-oriented approach of Integrated Services, the management of a differentiated services network remains a complex problem. Since the operation of a differentiated network involves numerous access routers, core routers and servers, a consistent operation is difficult to achieve by independently configuring each device. In this paper, we explore a scheme to enable a network administrator to manage and configure DiffServ networks from a central location and also abstract away the specific details of device configuration, and allow him/her to express the management of the network in terms of application-oriented performance metrics. This leads to a simplification of network management task, which can be exploited to support business needs of an enterprise network, such as honoring Service Level Agreements provided to its customers.

Policy management for networked systems and applications

In this paper, we present a novel policy middleware architecture for managing IT systems and applications that span multiple networks and administrative domains. The proposed policy middleware provides a standard infrastructure for the creation, storage, distribution, and execution of policies, and helps in reducing the cost of making IT systems policy-aware. In particular, we focus on three aspects of the proposed policy middleware that help in making the middleware fully general: (1) a platform-neutral and extensible specification of policies; (2) the local ratification of policies, which lets system administrators accept, reject, or flag an incoming policy; and (3) the transformation of policies, which allows system administrators to transform incoming policies to match their local environment. We present our experience in building an application on the proposed middleware to audit the configuration of a storage area network. We also present performance results from a prototype and show that our policy middleware design can scale to handle a large number of policies.

A Policy Service for GRID Computing

In a distributed multi-institute environment like the GRID, each participating institute may want to enforce some limits on how its resources are being used by other institutes. We discuss how the concept of resource allocation policies can assist in this task. We then present an architecture for policy based resource management in the case of a single institute, and how a policy server based on GRID concepts can be developed. We then show how to extend the policy server to support virtual organizations.