Consider a local network with a 1 Gbps access link to the Internet. Hosts on this network areaccessing resources with an average size of 2 MB from a distant server at an average rate of 50requests per second.a.What is the link utilization of the access link to the internet?b.Suppose these requests were to go through a caching proxy server. What would thelink utilization to the internet be if half of all requests were served from the cache of the proxyserver?с.resources never being needed for example.) Would this still provide any advantages to the enduser? Would there be any disadvantages to the end user?Suppose the proxy server could not serve any content from cache (due to the same

The LAN is mainly of two types wired LAN and wireless LAN. The wired LAN uses switches, servers, and…

Consider a local network with a 1 Gbps access link to the Internet. Hosts on this network are accessing resources with an average size of 2 MB from a distant server at an average rate of 50 requests per second. a. What is the link utilization of the access link to the internet? b. link utilization to the internet be if half of all requests were served from the cache of the proxy server? Suppose these requests were to go through a caching proxy server. What would the с. resources never being needed for example.) Would this still provide any advantages to the end user? Would there be any disadvantages to the end user? Suppose the proxy server could not serve any content from cache (due to the same

Consider a local network with a 1 Gbps access link to the Internet. Hosts on this network are accessing resources with an average size of 2 MB from a distant server at an average rate of 50 requests per second. a. What is the link utilization of the access link to the internet? b. link utilization to the internet be if half of all requests were served from the cache of the proxy server? Suppose these requests were to go through a caching proxy server. What would the с. resources never being needed for example.) Would this still provide any advantages to the end user? Would there be any disadvantages to the end user? Suppose the proxy server could not serve any content from cache (due to the same

Systems Architecture

7th Edition

ISBN:9781305080195

Author:Stephen D. Burd

Publisher:Stephen D. Burd

Chapter13: Internet And Distributed Application Services

Section: Chapter Questions

Problem 15VE

See similar textbooks

Similar questions

Assume a client is connected to the server and has already received an HTML webpage. It reads the webpage, and it now needs to get 3 new files, File A is 5 MB file B is 1 MB and file C is 1 KB. The client requests the files in the order A B C. The link has an RTT (round trip time) of 0.5 seconds and a bandwidth of 8 Mb/s(Megabits per second) (or 1 Megabyte per second). The client can reuse the open connection if the protocol allows it to. For all parts of this problem ignore header sizes, and start the timer when the client sends How long does it take to get file C under HTTP 0? How long does it take to get file C under HTTP 1 (assume the browser does not support pipeling)? How long does it take to get file C under HTTP 2 assuming a frame size of 1 KB and no server push? What event would make HTTP 3 faster than HTTP 2 for this use case (ignore TLS)?
A set of web browsers on the institutional network at USC generates an average of 15.0 requests/second for web objects of size 1.0 Mb. The access link to the public Internet is 15 Mbps. USC’s LAN operates at 1 Gbps. Assume LAN delay and internet delay are negligible. Suppose you installed a web cache and found that access link utilization was reduced to 9.0 Mbps. From your findings, what is the cache hit rate that resulted in this reduction in access link utilization?
In a network scenario, access link rate is 2 Mbps, RTT from the company router to server is 2 sec and web object size is 100K bits. If the average request rate from browsers to origin servers is 18 requests per second, what is the access link utilization? What are the problems associated with high link utilization? If a cache server with hit rate of 60% is used, what is the access link utilization?
(a) Suppose a server S and client C are connected over the Internet. The one-way prop- agation delay from S to C is 50 ms. The maximum throughput between S and C is R = 200 Mbps. A browser on client C makes an HTTP request for a webpage on server S. The base HTML file is of size 500 KB and it references five objects, each of size 5 MB. Find the total response time for the client to receive the entire webpage using nonpersistent HTTP with up to two parallel connections. Assume that when two par- allel connections are active, the throughput for each connection is 40% of the maximum throughput R. (b) Suppose an application running on host ece.gmu.edu needs to resolve the domain name cs.vtech.edu. Draw a diagram (with labels) showing the sequence of queries/responses in a recursive DNS query to find the answer in a scenario where all levels of the DNS hierarchy are involved.
Consider Figure 2.12, for which there is an institutional network connected to the Internet. Suppose that the average object size is 1,000,000 bits and that the average request rate from the institution’s browsers to the origin servers is 16 requests per second. Also suppose that the amount of time it takes from when the router on the Internet side of the access link forwards an HTTP request until it receives the response is three seconds on average (see Section 2.2.5). Model the total average response time as the sum of the average access delay (that is, the delay from Internet router to institution router) and the average Internet delay. For the average access delay, use ∆/(1 - ∆b), where ∆ is the average time required to send an object over the access link and b is the arrival rate of objects to the access link. Find the total average response time. I get ∆=1000000/15000000= 1/15, then ∆/(1 - ∆b)= (1/15)/(1-(1/15)*16)=-1, so the finally answer is : 3+(-1)=2s or 3+0=3s?
Computer Science Assume the length of each message is L=5, the access link has a speed of X=180 Mbps, and there are B=6 messages per second on average. What is the total average delay for receiving a message when no cache is used, i.e., the sum of LAN delay, access delay, and internet delay? Give your answer in milliseconds.
A frame containing http request is sent from Computer (A) [in whichever subnet it is now, make sure to show it in your figure], to the access point it is associated with. Draw the address fields (1, 2, and 3) of the frame travelling from Computer A to AP and the source and destination addresses of the frame travelling from AP to R1. The MAC addresses of AP1, AP2, and AP3 are M1, M2, and M3 respectively, and the Router R1’s MAC address connected to this Switch/AP is MRA. IP address values are already given, and the port addresses could also be used as given. The Router’s MAC address facing WAN side is MRW.
A file of size 20 KiloBytes is transmitted to a destination over a 10 Megabit/s network link (1 Mega = 10^6, 1 Kilo = 10^3, 1 byte = 8 bits). The propagation delay to the destination is 40 milliseconds (1 milli = 10^−3). Assume the queueing delay encountered by packets of the file is negligible. What is the total delay (in milliseconds) for the file to get to its destination?
Download delays for 100 objects (HTTP 1.1 with local web caching). Consider an HTTP 1.1 client and server. The RTT delay between the client and server is 2 seconds. Suppose the time a server needs to transmit an object into its outgoing link is 3 seconds. There is also a local web cache, as shown in the figure below, with negligible (zero) propagation delay and object transmission time. The client makes 100 requests one after the other, waiting for a reply before sending the next request. All requests first go to the cache (which also has a 2.0 sec. RTT delay to the server but zero RTT to the client). How much time elapses between the client transmitting the first request, and the receipt of the last requested object, assuming no use of the IF-MODIFIED-SINCE header line anywhere, and assuming that 50% of the objects requested are "hits" (found) in the local cache? Your answer should be among the following list( 702 secs, 552 secs, 352 secs, 350 secs, 150 secs) . Show your…
Consider the following illustration of a proxy server, Client Client Client Transmission rate R Proxy Cache Server Transmission rate: R₂ Internet Web Server Assume that HTTP messages containing objects are 1 KB and that HTTP messages not containing objects can be ignored as they do not produce a significant delay. Also, assume the transmission rate of the proxy server, Rp = 20 Mb/s, and the transmission rate of the webserver is Rs = 24 Mb/s. If clients transmit on average 1100 HTTP requests per second and the proxy server has a cache hit rate of 30%, what is the traffic intensity at the link connecting the proxy server to the Internet? (provide your answer to 2 significant figures)
Consider the figure used to illustrate Web caching below. Suppose that the access link capacity is C bits/sec and the average object size is S bits and that the average request rate from the institution’s browsers to the origin servers is A requests/sec. Also, suppose that the amount of time it takes from when the router on the Internet side of the access link forwards an HTTP request until it receives the response is T secondson average. Model the total average response time perceived by the institutional users as the sum of the average access delay (that is, the delay from the Internet router to institution router) and the average Internet delay. For the average access delay, use D/(1 − DB), where D is the average time required to transmit an object over the access link and B is the arrival rate of objects to the access link. Note that this access delay includes both the transmission and queuing delays. (Note also that B = A if there isno caching.) Ignore the details of persistent or…
Consider the figure used to illustrate Web caching below. Suppose that the access link capacity is C bits/sec and the average object size is S bits and that the average request rate from the institution’s browsers to the origin servers is A requests/sec. Also, suppose that the amount of time it takes from when the router on the Internet side of the access link forwards an HTTP request until it receives the response is T secondson average. Model the total average response time perceived by the institutional users as the sum of the average access delay (that is, the delay from the Internet router to institution router) and the average Internet delay. For the average access delay, use D/(1 − DB), where D is the average time required to transmit an object over the access link and B is the arrival rate of objects to the access link. Note that this access delay includes both the transmission and queuing delays. (Note also that B = A if there isno caching.) Ignore the details of persistent or…