Problem 4 Consider hosts in an institutional network accessing content via the following network. Suppose each object is 80K bits, hosts in the institutional network generate 18 requests/sec, and hosts from other parts of the Internet (not shown) generate 100 requests/sec. Suppose that the total delay for Router2 to send a request to Router3 and Router3 to send the response back to Router2 is 2 seconds. Ignore propagation delays for other links. Ignore delays for Conditional GET messages and their responses. Approximate the access link delay (including queuing and transmission delays) by 1/(u - 2), where u is the service rate and is the arrival rate (unit: objects/sec). blir Router3 R. = 20 Mbps Internet Router4 origin Content servers provider 1 Gbps LAN RTT = 2 sec Router2 R. = 1.54 Mbps Router1 1 Gbps LAN cache institutional network a) Find the total delay for obtaining one object from the origin server to a host in the institutional network. b) Suppose that 20% of requests generated by the institutional network are served by a local cache (i.e., the cache hit rate is 0.2). Repeat a). c) What is the minimum cache hit rate to make the delay no greater than 100 ms