Computer Science 825 Quiz 5 Name _______________________ 1. Suppose a token bus system has 3 priority classes 3, 2, and 1. The token holding times for the classes are respectively 800us 400us and 200us. What percent of the bandwidth is dedicated to class 2 traffic? 2. a. Suppose a token ring transmits data at a rate of 10,000,000 bits per second. How many microseconds does it take to take to transmit 1 bit. b. Suppose signal propogation speed is 200,000,000 m/sec and the stations on a token ring are an average of 40 meters distant from each other. How many microseconds does it take the signal to propogate from one station to another. c. Suppose the ring has 100 stations and each station introduces a propogation delay of 1 bit time. What is the average delay (in usec) experienced by a station after it becomes ready but before it can begin transmitting on an IDLE RING. (Hint: Divide the maximum time by 2). 3. For the IEEE token bus match the control packet that will be generated as a result of each of the following conditions. Some answeres may be used 0 times or more that one time! ____ a. A station recognizes a WHO_FOLLOWS 1. SOLICIT_SUCCESSOR_2 packet naming its predececessor. 2. WHO_FOLLOWS ____ b. A station wishes to leave the net in an orderly way. 3. SET_SUCCESSOR ____ c. A collision occurs when two 4. RESOLVE_CONTENTION stations try to claim the token at the same time. 5. CLAIM_TOKEN ____ d. A station wishes to respond to a 6. SOLICIT_SUCCESSOR SOLICIT_SUCCESSOR frame. ____ e. A station times out twice after sending a WHO_FOLLOWS frame. 4. Two standard measures of network performance are sustainable throughput and mean packet delay. High sustainable throughput is good and low mean packet delay is good. For each of the following select the answer that bests compares CSMA/CD with token passing. Assume identical transmission speeds. a. Sustainable throughput at very high loads 1. CSMA/CD is better 2. Token passing is better 3. No measureable difference b. Packet delay at very high loads 1. CSMA/CD is better 2. Token passing is better 3. No measureable difference c. Packet delay at very low loads 1. CSMA/CD is better 2. Token passing is better 3. No measureable difference 5. The effect of packet size on sustainable throughtput in bytes per second (assume standard headers + user data are included in byte / second computations) is: a. More significant in token b. More significant in CSMA-CD passing than in CSMA-CD than in token ring c. Completely insignificant d. Very significant in both. in both. 6. In an 802.5 token ring system suppose the following events occur: Station A transmits to E using priority 3 token Station C makes a priority 5 reservation Station A generates a priority 5 token Station B transmits a priority 5 message to station C Station B transmits a priority 5 token Station C transmits a priority 5 message to station B Who is responsible for regenerating a priority 3 token?