1. Continuing with the prior question, suppose you inserted atransparent web caching server (3 & 4 in the diagram, let'scall it WCS) that was 2 ms RTT away from the client (1) and 28 msRTT away from the server (6). Specifically, 1 ms is required forany client to propagate a bit to the router (2) and vice versa, and1 ms to propagate across the link between the router (2) and WCS(3). It takes 27 ms to propagate a bit between the router (2) tothe real web server (6). That way a trip from the client tothe WCS and back to the server still takes 30ms.We will use the same transmission times of 0.75 ms for any HTTPobject that needed to be sent from any device to another, and solittle that we'll call it zero for any other type of HTTP packet.The router adds zero queueing delay and processing delay but likethe servers does have to account for transmission delay every timeit receives an object on one link and decides to transmit it ontoanother. Ignore TCP handshakes for now.Finally, the % of objects that had been modified stays thesame. If the object that you need is in the WCS, but you are using theIF-MODIFIED-SINCE request to determine if it's OK to re-use it,here is what happens:* the client sends an HTTP request with IF-MODIFIED-SINCE totowards the server. * the router intercepts it and retransmits it to the WCS* the WCS sees that it has the object, but does not know if it hasbeen modified since it cached it* the WCS initiates a new HTTP request with IF-MODIFIED-SINCEtowards the server (6) which the router receives first and thenretransmits to (6). * The server responds with an indication that the object has notbeen modified, and may be used from cache by sending a packet backtowards the WCS * the router receives this response packet and forwards it to theWCS* the WCS sends an HTTP response with the object towards the clientwhich the router receives and retransmits to the client.How long will this take? Give your answer inms.
1 Continuing With The Prior Question Suppose You Inserted A Transparent Web Caching Server 3 4 In The Diagram Let 1 (18.03 KiB) Viewed 27 times
2. Continue with the prior question withthese changes:If the object that you need is in the WCS, but you are using theIF-MODIFIED-SINCE request to determine if it's OK to use it, hereis what happens:* the client sends an HTTP request with IF-MODIFIED-SINCE totowards the server. * the router intercepts it and retransmits it to the WCS* the WCS sees that it has the object, but does not know if it hasbeen modified since it cached it* the WCS initiates a new HTTP request with IF-MODIFIED-SINCEtowards the server (6) which the router receives first and thenretransmits to (6). * The server responds with an indication that the object has beenmodified, includes the fresh copy of the object in itsresponse. You need to consider the remaining missing steps, and then give atotal time for this scenario to happen. Give your answer in ms.
1 Continuing With The Prior Question Suppose You Inserted A Transparent Web Caching Server 3 4 In The Diagram Let 2 (17.6 KiB) Viewed 27 times
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