5. Consider Scenario 1. An institutional network utilizes a 20 Mbps link to connect to the public internet and reach some origin web servers. The content files stored on the origin servers have an average size of 100 Kbits. The cumulative request rate from the institution browsers is 150 req/sec. The time between the moment in which the router on the internet side of the access link forwards an HTTP request to the origin servers and the moment in which it receives a response from them is 5 seconds (internet delay). Assume that HTTP requests are negligibly small. Consider Scenario 2 where the institutional network adopts a proxy server which serves requests within the LAN in 19msecs, with an average hit rate of 0.8. With the proxy, the average access link delay experienced by requests drops to 10 msecs. a) Calculate the utilization of the LAN and of the access link in Scenario 1. b) Calculate the utilization of the access link in the second scenario. c) Calculate the average delay experienced by the requests in the second scenario. Origin servers Public Internet 20 Mbps access link 100 Mbps LAN Institutional network Public Internet 20 Mbps acces link 100 Mbps LAN KELLO Institutional network Proxy

5. Consider Scenario 1. An institutional network utilizes a 20 Mbps link to connect to the public internet and reach some origin web servers. The content files stored on the origin servers have an average size of 100 Kbits. The cumulative request rate from the institution browsers is 150 req/sec. The time between the moment in which the router on the internet side of the access link forwards an HTTP request to the origin servers and the moment in which it receives a response from them is 5 seconds (internet delay). Assume that HTTP requests are negligibly small. Consider Scenario 2 where the institutional network adopts a proxy server which serves requests within the LAN in 19msecs, with an average hit rate of 0.8. With the proxy, the average access link delay experienced by requests drops to 10 msecs. a) Calculate the utilization of the LAN and of the access link in Scenario 1. b) Calculate the utilization of the access link in the second scenario. c) Calculate the average delay experienced by the requests in the second scenario. Origin servers Public Internet 20 Mbps access link 100 Mbps LAN Institutional network Public Internet 20 Mbps acces link 100 Mbps LAN KELLO Institutional network Proxy

Database System Concepts

7th Edition

ISBN:9780078022159

Author:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan

Publisher:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan

Chapter1: Introduction

Section: Chapter Questions

Problem 1PE

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