NetScript is a language system for dynamically programming and deploying protocol software in an active network. NetScript programs are packet flow processors composed out of dataflow components. They can be dynamically dispatched to remote nodes, composed with installed software, and executed to enhance node functions. NetScript has proven useful for implementing a variety of practical network systems including Internet protocol (IP) routers, firewalls, protocol analyzers, traffic shapers, load balancers, various queuing disciplines, intrusion detection systems, Web transport protocols, and IP telephony systems. The paper illustrates the principal concepts of NetScript with an example application, an active IP router that is dynamically extended to provide firewall protection.

This paper describes novel protection technologies, developed by the MarketNet project at Columbia University, that shifts power from attackers to defenders, giving the defenders control over the exposure to attacks and over detectability and accountability of attackers. MarketNet uses market-based techniques to regulate access to resources. Access to a resource must be paid-for with currency issued by its domain. Domains can control the power of attackers by limiting the budgets allocated to them, and control the exposure of resources by setting their prices, effectively providing a quantifiable access control mechanism. Domains can monitor currency flows and use uniform resource-independent statistical algorithms to correlate and detect access anomalies indicating potential attacks. Currency is marked with unique identifiers that permit domains to establish verifiable accountability in accessing their resources. Domains control and fine tune their exposure to attacks; adjust this exposure in response to emerging risks; detect intrusion attacks through automated, uniform statistical analysis of currency flows; and establish coordinated response to attacks. MarketNet mechanisms unify and kernelize global information systems protection by containing all protection logic in a small core of software components. The paper presents the architecture and operation of MarketNet along with the design and implementation of the main architectural components. The paper illustrates the application of MarketNet to the protection of the simple network management protocol (SNMP) and compares it with the security features offered by SNMPv3.

Several QoS provisioning mechanisms such as differentiated services (Diffserv) and integrated services (Intserv) have been recently devised and applied to bring quality of service (QoS) to the Internet. This paper studies end-end QoS performances of two QoS-demanding applications using different transport protocols. Both applications are tested in a real network environment, with end-end QoS provisioning by Intserv. They use QoSockets, a new extension of QoS specification and management to the Berkeley sockets. Their performance in terms of throughput, delay, jitter, and loss are measured under a number of test cases combining several factors: (1) single or multiple flows, with or without resource reservations; (2) normal, heavy, or overloaded scenarios; (3) uni- or bi-directional streams; and (4) TCP or UDP protocols. The experimental results show that the performance of two applications with the Intserv resource reservations are significantly improved, but not always guaranteed. It is also shown that UDP applications are able to get the requested QoS while TCP applications may not because of the nature of its bi-directional traffic flow. The paper provides detailed interpretation of the results and provides generic conclusions on application QoS.

The distributed resource controller (DRC) technology described in this paper provides a novel approach to interfacing applications with emerging network mechanisms to deliver quality of service (QoS) and controlling network resource utilization. DRC aims to unify network services (e.g., Diffserv, Intserv, and ATM) and application QoS provisioning by introducing a middleware system and a set of generic interfaces. DRC middleware is the core part that translates application requests for QoS delivery into respective access to underlying network systems in a manner that optimizes resource utilization and shelters applications from such a complexity. Applications can request QoS to the DRC middleware in two ways: either on-line using the DRC QoS API or off-line via the DRC utility. Application QoS requirements are specified in terms of two categories of parameters: traffic profile (quantitative) and user expectation (qualitative). DRC currently uses the CORBA-based object-oriented technology to develop a CORBA-based resource controller (CRC). The working CRC prototype built to manage the integrated services is also presented.

This paper describes novel market-based technologies that uniquely establish quantifiable and adjustable limits on the power of attackers, enable verifiable accountability for malicious attacks, and admit systematic and uniform monitoring and detection of attacks. These technologies, incorporated in the MarketNet system, establish a financial economy to regulate the trade and use of access rights in information systems. Resources are instrumented to use currency for access control and monitoring, establishing accountability in their use. Domains control access to their resources through resource prices and budgets available to clients. Domains control and fine tune their exposure to attacks; adjust this exposure in response to emerging risks; detect intrusion attacks through automated, uniform statistical analysis of currency flows; and tune their exposure to resource unavailability by purchasing protection through financial-like instruments.

Configuration management presently requires complex labor-intensive processes by experts. A single configuration task-installing/reconfiguring a system, or provisioning a service-typically involves a large number of activities fragmented among multiple network elements, each with its own proprietary configuration management instrumentation and tools. A change may cause configuration inconsistencies resulting in failures or inefficiencies; undoing changes to recover an operational state is often very difficult or even practically impossible. Therefore, configuration management is very costly, error prone, and often results in unpredictable failures and costly recovery. NESTOR seeks to replace labor-intensive configuration management with one that is automated and software-intensive. Configuration management is automated by policy scripts that access and manipulate respective network elements via a resource directory server (RDS). RDS provides a uniform object-relationship model of network resources and represents consistency in terms of constraints; it supports atomicity and recovery of configuration change transactions, and mechanisms to assure consistency through changes. RDS pushes configuration changes to network elements using a layer of adapters that translate operations on its object-relationship model to actions on respective elements. NESTOR has been implemented in two complementary versions and is now being applied to automate several configuration management scenarios of increasing complexity, with encouraging results.

Distributed multimedia applications are sensitive to the quality of service (QoS) delivered by underlying communication networks. The main question this work addresses is how to adapt multimedia applications to the QoS delivered by the network and vice versa. We introduce QoSockets, an extension to the sockets mechanism to enable QoS reservation and management. QoSockets automatically generates the instrumentation to monitor QoS. It scrutinizes interactions among applications and transport protocols and collects in QoS management information bases (MIB) statistics on the QoS delivered. The main advantages of QoSockets are the following: (1) support of single API for transport-layer QoS negotiation, connection establishment, and data transmission; and of single API for OS QoS negotiation; (2) support of a single QoS negotiation protocol; (3) generality across application QoS needs; (4) automatic management of application QoS needs. QoSockets are available for Solaris and Linux and support RSVP, ATM adaptation, ST-II, TCP/UDP, and Unix native protocols.

An overview is given of a switching architecture for high-speed networks called Isochronets, which time-divide network bandwidth among routing trees. Traffic moves down a routing tree to the root during its time band. Network functions such as routing and flow control are entirely governed by band timers and require no processing of frame header bits. Frame motions need not be delayed for switch processing, allowing Isochronets to scale over a large spectrum of transmission speeds and support all-optical implementations. The network functions as a media-access layer that can support multiple framing protocols simultaneously, handled by higher layers at the periphery. Internetworking is reduced to a simple media-layer bridging. Isochronets provide flexible quality of service control and multicasting though allocation of bands to routing trees. They can be tuned to span a spectrum of performance behaviors outperforming both circuit and packet switching.>

Abstract In a distributed system, data servers (file systems and databases) can easily become bottlenecks. We propose an approach to offloading data access requests from overloaded data servers to nodes that are Idle or less busy. This approach is referred to asremote caching, and the idle or less busy nodes are calledmutual serversas they help out the busy server nodes on data accesses. In addition to server and client local caches, frequently accessed data are cached in the main memory of mutual servers, thus improving the data access time in the system. We evaluate several data propagation strategics among data servers and mutual servers. These include policies in which senders are active/passive and receivers are active/passive in initiating data propagation. For example, an active sender takes the initiative to offload data onto a passive receiver. Simulation results show that the active‐sender/passive‐receiver policy is the method of choice In most cases. Active‐Sender policies are best able to exploit the main memory of other Idle nodes in the expected normal condition where some nodes are overloaded and others are less loaded. AH active policies perform far better than the policy without remote caching even in the degenerated case where each node is equally loaded.

The authors propose a distributed caching approach to off-loading data access requests from overloaded data servers in a distributed system to nodes that are idle or less busy. Helping out the busy servers on data accesses, the idle or less busy nodes are called mutual servers. Frequently accessed data are cached in the main memory of mutual servers in addition to server and client local caches. The authors evaluate several data propagation strategies among data servers and mutual servers. Simulation results show that the active-sender passive-receiver policy is the method of choice in most cases. Active-sender policies are best able to exploit the main memory of other idle nodes in the expected normal condition where some nodes are overloaded and others are less loaded. All active policies perform far better than the policy without distributed caching.>