Delayline: A Wide-Area Network Emulation Tool

Programming distributed applications is already potentially difficult, although tools exist to aid in their creation. Applications developed to communicate over local area networks can expect to enjoy highly reliable communications with minimal latency. However, such applications may no longer continue to perform as expected if moved to a wide-area network environment, due to the reduced performance inherent in wide-area networking. During application development it is often impractical or inconvenient to evaluate application performance under real wide-area network conditions. In this paper we describe the design and implementation of the Delayline tool which provides a fully configurable mechanism for emulating wide-area network communications on a local area network. Delayline allows real distributed applications to be evaluated under emulated wide-area network communication characteristics. @ 1994 The USENIX Association, computing systems, vol. 7 . No. 3 . summer 1994 313