The proliferation of Local Area Networks(LANs)to support distributed applications and to share expensive resoturces has created a need to inter-connect these networks across large geographical areas.Several Wide Area Network(WAN)technologies and services have evolved to address this need.They rage from X.25 that typically operates at 9.6 or 56 Kb/s,to Frame Relay and Switched-Multi Mega bit Data Service(SMDS)operating at 1.5-45 Mb/s,and eventually to Broadband Integrated Services Digital Networks(B-ISDN)operating at hundreds of mega bits per second using cell relay Asynchronous Transfer Mode(ATM)technology.Since communications networks play avital role in distributed computing environments,an application's performance depends heavily on the quality of service provided by the communications networks.To assure a high performance wide area network design,applications'delay requirements and traffic characteristics must be well understood.This paper provides information about the characteristics of WAN traffic based on real measurements from Bellcorc's backbone network that connects remote sites using dedicated T1 links.This paper also suggests some workload models that can be used for widea area network sizing and performance evaluation studies.
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