Answering what-if deployment and configuration questions with wise

Mukarram B. Tariq, Amgad Zeitoun, Vytautas Valancius, Nick Feamster, Mostafa Ammar

Research output: Contribution to journalConference articlepeer-review

42 Scopus citations


Designers of content distribution networks often need to determine how changes to infrastructure deployment and configuration affect service response times when they deploy a new data center, change ISP peering, or change the mapping of clients to servers. Today, the designers use coarse, back-of-the-envelope calculations, or costly field deployments; they need better ways to evaluate the effects of such hypothetical "what-if" questions before the actual deployments. This paper presents What-If Scenario Evaluator (WISE), a tool that predicts the effects of possible configuration and deployment changes in content distribution networks. WISE makes three contributions: (1) an algorithm that uses traces from existing deployments to learn causality among factors that affect service response-time distributions; (2) an algorithm that uses the learned causal structure to estimate a dataset that is representative of the hypothetical scenario that a designer may wish to evaluate, and uses these datasets to predict future response-time distributions; (3) a scenario specification language that allows a network designer to easily express hypothetical deployment scenarios without being cognizant of the dependencies between variables that affect service response times. Our evaluation, both in a controlled setting and in a real-world field deployment at a large, global CDN, shows that WISE can quickly and accurately predict service response-time distributions for many practical What-If scenarios.

Original languageEnglish (US)
Pages (from-to)99-110
Number of pages12
JournalComputer Communication Review
Issue number4
StatePublished - 2008
EventACM SIGCOMM 2008 Conference on Data Communication, SIGCOMM'08 - Seattle, WA, United States
Duration: Aug 17 2008Aug 22 2008

All Science Journal Classification (ASJC) codes

  • Software
  • Computer Networks and Communications


  • Content distribution networks
  • Performance modeling
  • What-if scenario evaluation


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