Week 5 Fundamentals of Network Communication PDF

 

Peer-graded Assignment: Fundamentals of Network and Digital Communication

Please give an answer to each question concisely. 1. Raise two main advantages of packet switching, compared to message switching.

2. Give Given n  a 20 20-b -bit it fr fram ame e and and bi bitt-er erro rorr-ra rate te p in comm commun unic icat atio ion. n. What What is the the prob probab abil ilit ity y that that the frame has no error? What is the probability of 1-bit errors? 3. Give  two features that the data link layer and transport layer have in common, and further give two features in which they differ. 4. Whic Which h  OSI layer is resp spo onsib nsible le fo forr (a) dete determ rmiining ning th the e best path path to rout route e pack cke ets ts;; (b (b)) prov proviiding ding end-to d-to-e -end nd  rel relia iab ble comm ommunic nicatio tions; ns; (c (c)) prov proviiding ding node node-t -to o-n -no ode reli lia able ble communications? 5. How How  does does the the netw networ ork k la laye yerr in a conn connec ecti tion on-o -ori rien ente ted d pack packet et-s -swi witc tchi hing ng netw networ ork k diff differ  er  from the network layer in a connectionless packet-switching network?  ANSWERS : Reduci Redu cing ng de dela lay, y, The The fi firs rstt pack packet et of a mult multii pack packet et mess messag age e ca can n be fo forw rwar arde ded d be befo fore re th the e se seco cond nd one has completely arrived. Probability I. Probab Probabili ility ty tha thatt th the e frame frame has has no erro error, r, P P=(1 =(1-p) -p)20 20P= P=(1(1-p)z p)z II. II. Pr Prob obab abil ilit ity y of 1-bi 1-bitt error errors, s, P=(2 P=(201 01)p )p(1 (1-p -p)1 )19 9 Data layer & Transport layer ❖ Two features that the data link layer and transport layer have in common ● Both layers layers offer offer recovery recovery from transmis transmission sion errors. errors. ● Pr Prov ovid ides es fl flow ow cont contro rol. l. ❖ Two features that the data link layer and transport layer differs : ● Data layer  can be used for transmission of data while transport layer is not used for data transmission. ● Data llayer ayer has has only only 2 layers layers while while the the transpor transportt layer layer consists consists of of 4 layers. layers. OSI layers  A. Network layer layer B. Tran Transp spor ortt laye layerr C. Tran Transp spor ortt layer layer

 

  Network layer ● Connection oriented  service is related to the telephone system. It includes the conn connec ecti tion on es esta tabl blis ishm hmen entt  an and d conn connec ecti tion on term termin inat atio ion. n. In conn connec ecti tion on-o -ori rien ente ted d serv servic ice, e, the Handshake  method is used to establish the connection between sender and ●

receiver. Connection-less service  is related to the postal system. It does not include any conne con necti ction on estab establis lishm hmen entt  and and conne connecti ction on termi termina natio tion. n. Conn Connect ection ion less less Se Servi rvice ce do does es no nott give the  guarantee of reliability. In this, Packets do not follow the same path to reach their destination.

A bit bit  st stre ream am 11 1101 0101 0110 1011 11 is tran transm smit itte ted d usin using g the the st stan anda dard rd CR CRC C me meth thod od.. Th The e poly polyno nomi mial al generator is  x+ x + 1. What is the actual bit string transmitted? Show the major steps to your answer. Bit stream= 1101011011 The bit stream is transmitted, Polynomial generator = x+x=1 The Bit form = 111 Thus, n=3.

Suppose a  IP header consists of four 16-bit words: (11111111 11111111, 11111111 0000 000000 0000 00,, 11 1111 1100 0000 00  1111 111100 0000 00,, 1100 110000 0000 00 1100 110000 0000 00). ). Plea Please se find find the the Inte Intern rnet et ch chec ecks ksum um for the code. bO = 11111117 11111111 = 2416- 1 = 65535 b1 = 11111111 00000000 = 65280 b2 = 11110000 11110000 = 61680 b3 = 11000000 11000000 = 49344 x= b0 + b1 + b2 + b3 modulo 65535 = 241839 modulo 65535 = 45234 b4 = -x modulo 65535 = 20301 The internet checksum = 01001111 01001101

 

  Suppose that  a group of computers is connected to an Ethernet LAN. If the computers communicate only  with each other, does it make sense to use IP protocol in the comp ompute uters? Shoul hould d  th the e comp ompute uters run TCP dire direc ctl tly y over Eth the erne rnet? How How is addre dressin ing g handled?

Indeed, IP  convention can be utilized in the PC, since the IP convention is a lot of necessities for tending  to also as directing information on the Internet. Moreover, The PCs ought not run TCP TC P le legi giti tima mate tely ly  ov over er Ethe Ethern rnet et.. Sinc Since, e, the the co comp mput uter er ca can' n'tt ru run n pr prin inci cipl ples es ba base sed d TCP TCP with withou outt IP, IP, as TCP TCP  us uses es IP ad addr dres esse ses. s. Th Ther ere e is a need need to util utiliz ize e an in indi divi vidu dual al cu cust stom om stre stream amin ing g co conv nven enti tion on that depends on Ethernet or another link layer as a lower layer.

(1) The  figures below show the TCP/UDP communication pattern diagrams. Which diagram works for TCP? Why? (2) Fill the missing steps (blank boxes) in both diagrams for TCP/UDP correspondingly.  correspondingly. 

Answers : 1) Diagram  (b) will work for TCP, since it is a network protocol that shows the details of how data is sent as well as received. 2) Missing steps : (a) bind, connect , (b) bind>listen>accept, connect.