Introduction to Computing Sciences Lecture 04 PDF

Introduction to Computing Sciences Lecture 4: Networking: construction and operation on network, application of network and security issues. Hamisu Ismail AHMAD Nile University of Nigeria, Abuja Faculty of Computing Department of Cyber Security © Asim Balarabe Yazid ...

Introduction to Computing Sciences Lecture 4: Networking: construction and operation on network, application of network and security issues. Hamisu Ismail AHMAD Nile University of Nigeria, Abuja Faculty of Computing Department of Cyber Security © Asim Balarabe Yazid Summary of last lecture  Types of software  OS and its component  Component of kernel  File manager  Device drivers  Memory manager  Scheduler and dispatcher  Time-sharing between processes  Interrupt  Program switch/context switch  Time slice  Boot strapping  Security issues of computer © Asim Balarabe Yazid 2 Content  Network and its classification  Network protocol  Communication over a network © Asim Balarabe Yazid 3 Network  Network enables the share of information and resources.  Printer, software packages, and disk storage facilities. © Asim Balarabe Yazid 4 Classification of a network (1/3)  Local area network (LAN)  Small scale, usually within a diameter of a few kilometers (in a single building or building complex e.g., a company, school)  Metropolitan Area Network (MAN)  Medium scale, say, within a spanning of local community  Wide area network (WAN)  Large scale, may cover entire country or across countries © Asim Balarabe Yazid 5 Classification of a network (2/3)  Open network is a network that is design in a public domain and anyone can use it free without signing any license agreement (internet)  Closed network (proprietary) is a network that is controlled by a particular entity such as an individual or a company  allowing the company to draw income from selling or leasing some products. © Asim Balarabe Yazid 6 Classification of a network (3/3) Another way of classifying a network is based on the topology of a network, which refers to the pattern in which the machines are connected Ring Star computer computer computer computer computer computer computer computer computer computer computer Bus computer computer computer computer computer © Asim Balarabe Yazid 7 Protocol  A set rules governed on how transmission of data will occurs over a network is called a protocol.  Ring topology uses the token protocol originated by IBM 1970s to transmit data message on a network  The computer that has the token can send message on the network  The computer that doesn’t have token can only forward the message on the network  Message is transmitted in one direction.  Each computer on a ring topology forward the message to the next computer  Only the destination computer keeps a copy of the message before forwarding it  When the originating computer of the message receive the message it will not forward it. © Asim Balarabe Yazid 8 Communication over a ring network A B E c D © Asim Balarabe Yazid 9 Transmission in bus topology  Ethernet protocol uses the rule called “Carrier Sense, Multiple Access with Collision Detection (CSMA/CD)”  Each computer on the network has an address ID  All messages are broadcasted to all computers on the network  A computer only keeps the message addressed to it  If more than one computers try to send messages at the same time, they will all detect the “collision” and stop sending messages  They will try again later, after a random period of waiting © Asim Balarabe Yazid 10 Communication over bus topology © Asim Balarabe Yazid 11 Combining networks (1/2)  To connect two or more smaller networks to form a big network, we need some special devices  Repeater – a device that passes signals between two networks back-and-forth  Bridge – a device similar to a repeater, but it only performs “meaningful” message-forwarding  Switch – a bridge with multiple connections © Asim Balarabe Yazid 12 Combining networks (1/2)  A router is a device (maybe a computer) that connects two (possibly heterogeneous) networks together  The two networks may be using different protocols © Asim Balarabe Yazid 13 Inter-process communication  Inter-process communication (IPC) is the execution of process on a network where more than one machine need to coordinate to accomplish a task.  Example of inter-process communication  Client/server model (e.g network printer, disk storage)  Peer-to-pear model (e.g file transfer) © Asim Balarabe Yazid 14 Summary  Network and its classification  Topology (star, bus, circle)  Open and closed network  Scale (LAN, MAN, WAN)  Network protocol  Token protocol, carrier sense/multiple access collision detection  Communication over a network  Repeater, switch, bridge and router  Inter-process communication  Client/server and peer-to-peer communication © Asim Balarabe Yazid 15 Additional reading  Goldfarb, C. F. and P. Prescod. The XML Handbook, 5th ed. Upper Saddle River, NJ: Prentice-Hall, 2004.  Halsal, F. Computer Networking and the Internet, Boston, MA: Addison-Wesley, 2005.  Kurose, J. F. and K. W Ross. Computer Networking; A Tbp Down Approach Featuring the Internet, 3rd ed. Boston, MA: Addison- Wesley, 2003.  Peterson, L. L. and B. S. Davie. Computer Networks: A Systems Approach, 3rd ed. San Francisco: Morgan Kaufmann, 2003.  Stallings, W. Cryptography and Network Security, 4th ed. Upper Saddle River, NJ: Prentice-Hall, 2006. © Asim Balarabe Yazid 16 Glimpse of next class  The Internet and Its architecture  Internet application  Network security © Asim Balarabe Yazid 17 Lecture 04 Ends Question??? Thank you for coming. © Asim Balarabe Yazid 18