CMPS 297 Final, Spring 2001

Math 297C final exam Spring 2001 Duration 2 hours For each wrong answer in the True/False questions ipt will be de- ducted from your total score First Name: ..... .. Last Name: ..............20-. ID: 0... . 8pts) TCP is a connection oriented protocol (a) True (b) False 2. (3pts) IP is a comection oriented protocol (a) True (b) False 3. (3pts) It is possible that 2 IP packet send from host A to host B to follow clifferent routes (a) True (b) False . (Bpts) It is possible that 2 TCP segments belonging to the same connection send from host A to host B to follow different routes (aj True (b) False . (3pts) The port number in TCP(UDP)/IP is usec to distinguish be- tween different network interfaces on the same computer (a) True (b) False j. (3pts) Port munber 66000 is valid (a) True (hb) False 7. (3pts) Port number 67000 is valid (a) True (b) False 8. (3pts) In the L&2.61.150.128/25 network, the default router should be assigned the address 182.61.150.128 (a) True (b) False . (3pts) If a router receives a link state packet it forwards it on all its ports except the one it received the packet from. (a) True (hb) False . (3pts) In the link state protocol the age field is used to solve the count to infinity problem (a} True (b) False . (pts) The sequence number field in the link state packet is decremented everytime it is forwarded by a router {a) True (b) False 2, (3pts) The masini munber of routers an LP packet can pass through before reaching its destination is 16 (a) True (b) False 13. (Apts) Host A has established a TCP connection with host B. At a cer- tain time A’s convestion window is 40kbytes and B has just announced a tnaximum window size of |Okbytes. The next data that A sends can be no more than {a} LOkbytes (b) 40kbvtes (c) 25kbytes (d) 50kbytes ( ve) none of the above i4. (4pts) The length of an IP adelress is 15. (4pts) The network 192.168.216.128/25 can have a maximum of (a) 255 hosts (b) 256 hosts (c) L28 hosts (dl) 25 hosts (e) none of the above 16. (4pts)The maxinina length of an LP header is (a) 20 bytes (b} 10 bytes (c) 60 bytes (dl) 80 bytes (e) none of the above 2 % 7. (Apts}The rminimnim length of an [P heacler is (a) 20 bytes b) 40 bytes ( (c (cl) 80 bytes le ) ) 60 bytes } ) none of the above . (8pts) Assume that the timeout. interval for TCP is computed using the forraula: Timneout=RTT+ 1°D where RTT=0.5*RPT+0.5°M and D=0.5* D+0.5«|RTT — Al. At t=0 assume (he following: Timeout=1l0ms, RT T=2ms and D=2ms. Host A transmits a segment at t=0 and receives adn ack at t=5ms. Host A sends a second segment at t=l0ms. Host A will retransmit segment 2 ouly if it does not reecive an ack by t= ) 20ms )} 23.5ms 25.5ms C ( (I { ( cl) 30ms ~ You have been assigned the 200.35.L.0/24 address block. Your goal is to create the imaximum number of subnets that can accomodate 45 hosts each. (a) (2pts) Determine the subnet mask. (b) (2pts) What is the maximum nuraber of hosts thal can be assigned in each subnet? (c) (2pts) List the subnets in dotted decimal notation (cl) (2pts) List the range of valid host addresses in the second subnet 20. (LOpts) The network show in the figure below uses a distance vector al- gorithm. The segments AB and AC have a delay of 10.10 respectively. Construct the routing table for A (delayink) given that B,C,D have the following information . From B: To Delay From C: Delay From D: To Delay A iD 10 A 12 BO i) Bol4 C2 0 C15 Dos 7 C0 From A: To Delay A B ( D C Figure L: 21. (Spts) Host X has the following routing table Destination \lask Gateway [92 £68.216.0 Qt L92.168.217.0 £24 192.168.216.70 clefault * L92.168.216.1 arp(ip) denotes an ARP lookup for the [P address ip. In each of the following cases fill in the ip address. (ai Destination: 192. 168.216.1 arp(....0...00.. } (b) Destination: [92168.216.8 arp(...... 2...) (cj) Destination: 192.168.217.154 arp(....... 02... ) () Destination: 192.168.195.175 arpt.... 0... a) 22. (LOpts)Cousider the network depicted below. Suppose that there is a TCP connection between A and B, with data Howing from A to B, and 6 ack’s from B te A. B announces a maximum window size of 64kbytes and a maximiuin segment size of Lkbytes. Assume that host A will send as tuuch data as allowed by TCP flow control. All data segments send from A to B are Ikbvtes. The RTT between A and B is 100ms, and B acks the receip! of every clata packet(ie there is no lost our out of order packets) Figure 2: fa) How long does it take a packet to reach B i. 50ms ii. LOOms i. O.Olims iv. 0.08 ms (b) What is the maximum bandwidth that can be achievecl{ Mbps=Mega bits/second) i. LOOMDps ii, 10.21M bps 5.1 2M bps 50M bps iii. iv. (oe) How long does it take for A to transinit the first l5kbytes i. 300ms ii. 600s iii. OOOMs iv. 1500ms (d) Suppose that the links between A and B have been upgraded to IGbps. How long does it take A to transmit the first Lokbytes i. LO Cimes less ii. 10 times more iii. 3 Cimes Joss iv. 5 times more v. none of the above Version IHL Type of service Total length Identif ication Fragment offset Time to live Protocol Header checksum Source address Destination address Options (0 or more words) Fig. 5-45. The IP (Internet Protocol) header. Source port Destination port Sequence number Acknowledgement number Window size F | N Checksum Urgent pointer Options (0 or more 32-bit words) Data (optional) Fig. 6-24. The TCP header.