Quiz 6 Key CNT 5106C 1 April 2010 Instructions: Write your last name, then first initial in upper righthand corner of answer sheet, and write “Quiz 6” centered at top. Answer all questions. 1. What is the main difference between token bus and token ring LANs? Explain the consequences of this difference. 2. Why is Slotted ALOHA more efficient than pure ALOHA? Explain. 3. What medium access protocol is used by Ethernet? Describe and explain its advantages over ALOHA. KEY 1. The main difference between token bus and token ring is that the token ring is a physical ring, whereas the token bus is a logical ring with the nodes physically attached to a bus (broadcast medium). As a consequence, in token bus the ring structure must be maintained by the nodes through protocol messages to add/delete nodes in a particular place in the logical ring, and the token must be passed as a complete link layer frame. In token ring, the token circulates much faster (all other things being equal) since it is
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