Running head: COMPUTER NETWORKS1Student name: Punith kumar.SNStudent id: 11523674Computer Networks 12Student name: Punith kumar.SNStudent id: 11523674

Computer NetworksSubject Code: ITC431Assignment 4Punith Kumar Sheshagirihalli NarasimhaiahStudent Id: 11523674Lecturer: George zajkoCharles Sturt University

Q1

Solution: A nondeterministic protocol is incapable to compute the time to determine when the workstation will transmit data, since it is not known how many time the workstation must wait and it cannot precisely determine at what time work station will be permitted to transmit the data without any collision. For example CSMA/CD, In CSMA/CD network the workstation detects the medium for collision. If workstation detects collision it stops transmitting and waits for some time, this waiting time depends on the type of the CSMA/CD used and trys to retransmit again if collision is detected again the workstation will wait again. Which makes CSMA/CD to deal with collision more often if the network is busy and nearly 60 percent of the time is wasted resulting in low throughput.

Q2.Solution: The Timer is set by the wireless LAN device and waits for CTC reply from an access point before timer expires.

Q3.Solution: Certainly this layout will not work due to shorter range and higher frequency of IEEE 802.11a the signals experience difficulties to penetrating obstacles, concrete walls and ceilings.

Q4. Solution: We know that packet uses the IP address to find its route to destination. LAN protocol such as CSMA/CD uses frames to transmit data but frames doesnt have IP address field. Therefore IP header is removed and then IP datagram arrives at CSMA/CD local area network from a router, now message is broadcasted on a LAN by ARP protocol requesting, to which workstation the IP address belongs upon the request the corresponding workstation with that IP replies by sending a message containing its 48-bit MAC address and informs to send data using this MAC address.

Q5.Solution: Centralized routing: Advantage: All the routing information is located in centralized node, routing information are easily accessible. Updating routing information is easy since all the routing information is located at one centralized node. Disadvantage: If centralized node crashes entire network will be crashed.Distributed routing:Advantages: There is no centralized node which maintains all routing informations therefore if any one of the node crashes the entire network will not crash. Every node has its own routing table.Disadvantage: Obtaining proper routing information to each and every node is difficult because the routing information is distributed over the network. Hence difficult to update routing information.Adaptive routing:Advantages: Routing table responds to node failure, congestion or network variation and creates new routes avoiding problem zones in the network.Disadvantages: Whenever network experiences changes in congestion these information is updated to one or more nodes which in turn increases congestion.

Q6.Solution: Connectionless packet switching or datagram switching: the packet contains complete routing information and the packets are routed independently, predicting the path is difficult since packets may take different path to reach its destination often resulting out of sequence packet delivery. Examples are UDP, IP and Ethernet protocols.

Connection oriented packet switching or virtual circuit switching: All packets which belongs to same destination follows same logically connected path over the network. Virtual circuit breaks large volume of data into many packets and defines the best path to reach destination over the network, then every router in this path is informed that it must be participate in a specific transmission of the packets to destination, after the transmission is finished the path is released. Examples: TCP, X.25, Multiprotocol label switching.

Circuit Switching: in this method two communicating nodes on a network establishes dedicated communication circuit before they send and receive data, then all the data is sent or received on this dedicated path. Example telephone.

Conversation of two person on a telephone line via circuit-switched network

7Q.Solution:

Bus topologyStar topologyRing topology

Difference

In bus topology common single cable is shared by all other devices on the network often this cable is called backbone.All the devices are connected to central hub using RJ45 cableIn ring topology each device is connected to at least two other devices on a network to communicate. Data travels either clockwise or anticlockwise.

Entire network goes down in case of back bone failure.If hub fails entire network will go down.Entire network goes down if the loop is broken by any cable or device failure.

Similarities

In bus topology it is easy to find out problem nodes.In star topology also it easy find out problem nodes.As well in ring topology its easy manage and locate problems.

Prone to single point failure.Prone to single point failure.Prone to single point failure

Q8. Solution: Any business can use Virtual private network along with the tunneling protocol such as PPTP (Point to point tunneling protocol) to create a tunnel through internet to offsite business location to transmit secured data, this is reinforced by IP security for interchanging packets at IP layer. Public encryption keys are exchanged between sender and receiver for the working of IP Security.

Q9. Solution: ROWDATAPARITY

ROW 10 1 0 1 0 1 01

ROW 20 0 1 1 0 1 01

ROW 30 0 1 1 1 1 00

ROW 41 1 1 1 1 1 00

ROW 50 0 0 0 1 1 00

Longitudinal Parity 1 0 1 0 1 1 00

Q10.Solution: 10a. Station A waits for ACK after transmitting packet 0 without any error, if ACK is lost the station A timeouts waiting and retransmits packet 0.

10b. Station B sends ACK to station A with the number of next packet expected.For example:

10c. If the packet 0 sent by the station A to station B is lost in between, station B sends NAK to station A.

10d. Station B sends ACK to station A with the value of next packet number 901 upon receiving packets numbered 801 to 900 without any error as shown in figure below.

ReferencesWhite, Curt (2013). Data Communications and Computer Networks: A Business Users Approach (7th ed.). Course Technology:BostonTenenbaum, A. S., & Wetherall, D. J. (2011). Computer Networks (5th ed.). Boston, Massachusetts: Pearson Education, Inc.,.Packet switching. (2013, october 2). Retrieved from wikipedia: http://en.wikipedia.org/wiki/Packet_switchedCircuit switching. (2013, october 1). Retrieved from wikipedia: http://en.wikipedia.org/wiki/Circuit_switchingFAQ X.25 Protocol Support. (2013, september 29). Retrieved from sixnet: http://www.sixnet.com/content/faq-x25-protocol-support-117.cfmInternetworking elements. (2013, september 29). Retrieved from highteck: http://www.highteck.net/EN/Basic/Internetworking.htmlForouzan, B. A. (2010). TCP/IP Protocol suit (4th ed.). Boston: McGraw-hill companies.

Student name: Punith kumar.SNStudent id: 11523674

Student name: Punith kumar.SNStudent id: 11523674