Active Networks is a network infrastructure which is programmable on a per-user or even per-packet basis. Increasing the flexibility of such network infrastructures invites new security risks. Coping with these security risks represents the most fundamental contribution of Active Network research. The security concerns can be divided into those which affect the network as a whole and those which affect individual elements. It is clear that the element problems must be solved first, as the integrity of networklevel solutions will be based on trust of the network elements. In this

Research in active networking has resulted in a variety of working systems and experimental results obtained from these systems. More importantly, the active network research community has been identifying abstractions and principles with which first-generation results can evolve into large scale active networks serving many disparate applications. These abstractions are captured in architectures for execution environments, security and a node operating system, all of which we describe in this paper. 1 Introduction Active networks are networks which are programmable or customizable to application requirements. Thus, systems such as web proxy caches and firewalls can be seen as simplistic active networking technologies, and infrastructures with control plane programmability such as "open signalling" as increasingly flexible and sophisticated approaches to customizing network infrastructures. Research in active networks, however, has taken perhaps the most ambitious stance, that of allo...

We describe an active application in the field of multicast congestion control for real-time traffic. Our Active Layered Multicast Adaptation Protocol is a layered multicast congestion control scheme built on top of an Active Network infrastructure. It benefits from router support in order to obtain information about resources available and to perform the adaptation tasks at the places where shortage of resources occur. It supports heterogeneous receivers through the combination of layered multicast transmission with selective filtering and pruning of layers within the active nodes. Market-based resource management ideas are applied to achieve a resource utilisation level that represents an equilibrium between the user goals and the node operator goals. Our simulation results show that the protocol is feasible and provides adequate reactions to short term and persistent congestion, while keeping the amount of state and processing in the active nodes limited.

Telecommunication service providers have recently begun to offer ubiquitous access to packetised data. As a result, the Internet is not limited to computers that are physically connected but is also available to users that are equipped with mobile devices. This ubiquitous access fuels the growth and the usage of the Internet even further, and thus the realisation of dynamic Internet. With the realisation of the dynamic Internet, increasing support is needed for Internet protocol (IP) and transmission control protocol (TCP) over wireless/mobile networks. Two areas

For deployment of active network technology, active network applications play an important role. They should show good performance to users even under the condition that a small number of routers are equipped with active network technology. From performance aspects, crossing point of performance of active network application and end-to-end approach is very important. An active network application having a crossing point with a small number of active routers, will be a candidate of applications accelerating deployment of active network technology. In the paper, we first discuss about the following two important performance issues, “how many active routers bring good performance? ” and “what is a good location of active routers? ” We pick up two examples of active network applications, request routing in CDNs and reliable multicast, and show some interesting performance evaluation results from the viewpoint of these two issues. And we discuss about deployment issues by using these performance evaluation results. 1

In this paper, we overview the implementation of an algorithm to coordinate the congestion control algorithms of the TCP transport protocol and the ATM celloriented switching architecture. The novel idea uses ATM rate-based flow control to adjust the credit-based window size of TCP via the implementation of an agent. The effects of running TCP over ABR are studied with the help of two different environments (LAN and WAN). Firstly, we show that TCP window (CWND) and ABR Actual Cell Rate (ACR) are weakly correlated. Secondly, we derive an agentbased algorithm to ensure that even when the ATM switch queues are indicating no congestion, it is the switch (and not the source) which should control the increment in the TCP source rates. The introduction of the agent at the edge of the network coordinates the TCP and ATM sending transmission and clearly demonstrates a strong correlation coefficient between CWND and ACR. The simulation results show that coordination at the edge of the network ma...

Abstract—New conceptual ideas on network architectures have been proposed in the recent past. Current store-and-forward routers are replaced by active intermediate systems, which are able to perform computations on transient packets, in a way that results very helpful for developing and deploying new protocols in a short time. This paper introduces a new routing algorithm, based on a congestion metric, and inspired by the behavior of ants in nature. The use of the Active Networks paradigm associated with a cooperative learning environment produces a robust, decentralized algorithm capable of adapting quickly to changing conditions. Keywords—Artificial life, Cooperative Learning, Active Networks. I.

Recent advances in languages and execution environments (EEs) for active networks make it now possible to develop applications with this new exciting approach. In particular, active networks have proven to be very suitable for multicast services. Nevertheless, to open the network nodes to the code written by users requires the use of analysis techniques to avoid the degradation of the network performance. Model checking is one of the most powerful techniques to ensure software reliability. This technique has been successfully applied to many protocols developed with the classic (non-active) approach. Our aim is to extend its application to the area of active protocols. The paper consists of two main contributions: (a) a clear scheme to use the language PROMELA in order to formalize different elements in the active service (network EE, capsules and user applications) and (b) the practical (and successful) application of the approach to analyze an active multicast protocol using the model checker SPIN.

AMnet flexibly provides communication services inside the network. It is based on active networking and on a hardware/software codesign in order to improve efficiency. Group communication is explicitly addressed since it is an important paradigm for existing and emerging networked applications. The goal of the AMnet approach is the provision of scalable quality-based support for heterogeneous group communication. It uses so-called service modules for efficient and flexible service support within intermediate systems. This paper gives an overview of AMnet. The design of an AMnode as an active intermediate system with hardware-supported service capabilities is presented. Furthermore, a simple control and signalling suite for heterogeneous multicast services is proposed. Keywords--- Active Multicasting, Heterogeneous Group Communication, Adaptive Error Control I. INTRODUCTION Within the current Internet all systems interact via a handful of well-defined general purpose communication p...

In this paper we study the extent of negative interactions between TCP (Transmission Control Protocol) and ATM (Asynchronous Transfer Mode) congestion control through the application of an approach based on coordination via explicit cooperation. To do so, we implement an agent that bridges the gap between the ATM layer and the TCP layer in the protocol stack at the sender end to coordinate the congestion control algorithms of the TCP transport protocol and the ATM cell-oriented switching architecture. The novel idea uses ATM rate-based ow control to adjust the credit-based window size of TCP via the implementation of the agent. The effects of running TCP over ABR (Available Bit Rate) are studied with the help of two simulation models (LAN and WAN). Firstly, we show that TCP window (CWND) and ABR Actual Cell Rate (ACR) are weakly correlated. Secondly, we derive an agent-based algorithm to ensure that even when the ATM switch queues are indicating no congestion, it is the swi...