Q#4: (3 points) Consider the networks shown in the figure below. Assume computers in the institution send out 28 requests per second. Each object average size is 100,000 bits. Also assume the internet side delay of a request is 1.7 seconds. Using M/M/1 queue to model the access delay in the 5.5Mbps access link. The formula for the average response time is E[T]=1/(u- X), where is the arrival rate of objects to the access link and u is the service rate of the access link. origin servers public Internet 5.5 Mbps access link institutional network 100Mbps LAN institutional cache 1. Find the total average response time when no institutional cache is used. [Note: you should also use the M/M/1 queue formula to calculate the delay in internal Ethernet LAN.] 2. Now suppose the institutional cache is used. The hit rate for the cache is 0.7. Find the total average response time. Q#4: (3 points) Consider the networks shown in the figure below. Assume computers in the institution send out 28 requests per second. Each object average size is 100,000 bits. Also assume the internet side delay of a request is 1.7 seconds. Using M/M/1 queue to model the access delay in the 5.5Mbps access link. The formula for the average response time is E[T]=1/(-a), where is the arrival rate of objects to the access link and u is the service rate of the access link. 1. Find the total average response time when no institutional cache is used. [Note: you should also use the M/M/1 queue formula to calculate the delay in internal Ethernet LAN.] 2. Now suppose the institutional cache is used. The hit rate for the cache is 0.7. Find the total average response time. Q#4: (3 points) Consider the networks shown in the figure below. Assume computers in the institution send out 28 requests per second. Each object average size is 100,000 bits. Also assume the internet side delay of a request is 1.7 seconds. Using M/M/1 queue to model the access delay in the 5.5Mbps access link. The formula for the average response time is E[T]=1/(u- X), where is the arrival rate of objects to the access link and u is the service rate of the access link. origin servers public Internet 5.5 Mbps access link institutional network 100Mbps LAN institutional cache 1. Find the total average response time when no institutional cache is used. [Note: you should also use the M/M/1 queue formula to calculate the delay in internal Ethernet LAN.] 2. Now suppose the institutional cache is used. The hit rate for the cache is 0.7. Find the total average response time. Q#4: (3 points) Consider the networks shown in the figure below. Assume computers in the institution send out 28 requests per second. Each object average size is 100,000 bits. Also assume the internet side delay of a request is 1.7 seconds. Using M/M/1 queue to model the access delay in the 5.5Mbps access link. The formula for the average response time is E[T]=1/(-a), where is the arrival rate of objects to the access link and u is the service rate of the access link. 1. Find the total average response time when no institutional cache is used. [Note: you should also use the M/M/1 queue formula to calculate the delay in internal Ethernet LAN.] 2. Now suppose the institutional cache is used. The hit rate for the cache is 0.7. Find the total average response time
