of the internal behavior of the web server at the network protocol stack and the device driver. Many known server design optimizations for performance improvement were evaluated in this simulated environment. We discovered that WAN network characteristics may significantly change the behavior of the web server

Abstract—This paper analyzes web server performance under simulated WAN conditions. The workload simulates many critical network characteristics, such as network delay, bandwidth limit for client connections, and small MTU sizes to dial-up clients. A novel aspect of this study is the examination

Along with the fast progress the interconnection of computer systems makes the need for enterprise-wide distributed solutions grows. These systems have to support hundreds or even thousands of sites located all over the world. The distances between the sites will impose high communication costs on distributed activities thus significantly increasing their response times. This problem can be alleviated through migrating objects to the sites where they are needed. However, migration in such systems cannot be managed globally. Therefore, we present a migration protocol for (autonomous) objects which enables them autonomously to decide whether or not and which site to migrate to, thus making the system self-tuning. We also present two migration strategies objects can use to derive their migration decisions. The first one finds the optimal placement for an object while the second strategy in some cases returns a sub-optimal location but induces lower computation costs. The two s...

-to-end protocols, where loss recovery is performed by the sender; link-layer protocols, that provide local reliability; and split-connection protocols, that break the end-to-end connection into two parts at the base station. We present the results of several experiments performed in both LAN and WAN environments

Currently, the World-Wide Web (WWW) is the best-known and most widely used distributed multimedia application. By utilising the data services of a cellular telephone system, for example the digital GSM system, WWW can be brought to nomadic users. The advantage of using an existing cellular network like the GSM is that it takes care of terminal mobility, including location updates and handovers. The characteristics of cellular telephone links are, however, quite different from those of wireline links. The basic characteristics of any cellular telephone link are narrow bandwidth, highly variable transmission delays, and sudden disconnections. Therefore, such a link creates problems for WWW and other multimedia applications designed to operate with fast and reliable connections. WWW uses the HyperText Transfer Protocol (HTTP), which in turn is based on TCP. These protocols exhibit a number of performance problems in a wide-area mobile networks. In this paper we describe Mowgli...

Abstract: Intrusion Detection System (IDS) has been used as a vital instrument in defending the network from this malicious activity. With the ability to analyze network traffic and recognize incoming and on-going network attack, majority of network administrator has turn to IDS to help them in detecting anomalies in network traffic. The gathering of information and analysis on the anomalies activity can be classified into fast and slow attack. Since fast attack activity make a connection in few second and uses a large amount of packet, detecting this early connection provide the administrator one step ahead in deflecting further damages towards the network infrastructure. This paper describes IDS that detects fast attack intrusion using time based detection method. The time based detection method calculates the statistic of the frequency event which occurs between one second time intervals for each connection made to a host thus providing the crucial information in detecting fast attack.

a MAN/WAN environment. Our approach anticipates for bounds in specific quality metrics and is demonstrated by the experimental case-study of a high-priority service over a MAN topology.

Abstract. Recent proposals have shown that database replication providing 1copy-serializability can have excellent performance in LAN environments by using powerful multicast primitives. In this paper, we evaluate whether a similar approach is feasible in WAN environments. We identify the most

In this paper, we examine the bandwidth-constrained placement problem, focusing on trade-os appropriate for wide area network (WAN) environments. The goal is to place copies of objects at a collection of distributed caches to minimize expected access times from distributed clients to those objects

Testing in real life conditions is not as easy as it first seems, because often it is costly and difficult to reproduce Internet behaviour in controlled environment. WAN Emulator (WANE) proposed herein is a software tool that helps controlling the IP traffic parameters of a network, like delay