• University of Florida

• CNT 5106C

CISE Department, University of Florida CNT 5106C – Computer Networks, Spring 2014 Final Exam Instructor: Ye Xia Name (Last, First): SID: Email: 1. True or False (20 points total): Label each statement True or False (T/F). Grading Policy for this problem: Each wrong answer or no-answer faces 2-point deduction. Not answering a question also costs 2 points. The total deduction is no more than 20 points. 1) F 2) T 3) F 4) T 5) T 6) F 7) F 8) T 9) F 10) T 11) T 12) F 13) F 14) T 15) T 16) F 17) F 2. Short questions (20 points total; 4 points each): Please answer each question in 1-4 sentences. 1) This study source was downloaded by 100000859030508 from CourseHero.com on 12-15-2022 01:03:23 GMT -06:00 https://www.coursehero.com/file/11796667/final-solutions/ 2/6 Ans: The address space is flat, which makes it impossible to have hierarchical routing. Consequently, the routing algorithm will not converge quickly enough and the overhead from routing messages will be prohibitively high. 2) Ans: Exponential backoff: After a collision, a station will set a backoff timer and wait for that duration before attempting the next retransmission. The backoff timer is selected uniformly at random on the backoff interval. The following is the main answer for what the exponential backoff is: After each collision, the backoff interval is doubled. The exponential backoff ensures that stations with something to transmit will not continuously collide on the channel. It allows the stations to adapt to the traffic load of the channel/link. 3) Ans: RPF: A multicast router only forwards a multicast packet to other interfaces if the packet comes from an interface that is on the shortest path to the sender. Reason: RPF takes advantage of the existing unicast forwarding table. The router already knows which interface is on the shortest path back to the multicast sender, based on the unicast forwarding routing. In contrast, the outgoing interfaces on the forward shortest paths to the multicast receivers a