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Computer Networks

Computer Networks. Marwan Al- Namari Week 1. Unit Guide: Computer N etworks . Teaching Plan: Weeks 1 – 14 . Week 1-6 (In week 4 you will have a Quiz No.1 ) . Mid Term Holiday Mid-Term Exam . Week 7-14 (In week 10 you will have a Quiz No.2) .

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Computer Networks

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  1. Computer Networks Marwan Al-Namari Week 1

  2. Unit Guide: Computer Networks TeachingPlan: Weeks 1 – 14. Week 1-6 (In week 4 you will have a Quiz No.1) . Mid Term Holiday Mid-Term Exam . Week 7-14 (In week 10 you will have a Quiz No.2). Mode of Assessment : Final Exam (50 %)+Mid-Term Exam(20%) + Presentation (10%)+ Quizzes(10%) +Attendance (10%)

  3. References Computer Networking: A Top Down Approach 6th edition Jim Kurose, Keith RossAddison-WesleyMarch 2012 Computer Networks Andrew S. Tenenbaum, Computer Network, Prentice-Hall Computer Networks and Internet Douglas E. Comer, Computer Networks and Internet.

  4. What is computer network? What is networking? It is two computers(smart devices) or more connected by cables, repeaters ,switches hubs, access point(wirelessly). It is the process of sharing and exchanging information or data in the network.

  5. To improve our lives. To serve various applications. • To communicate via emails and voice (VoIP). To Share Data, Messages, Graphics, Printers, Scanners, Fax, Modem,….,… Why Networks? What is Internet? It is the largest engineered network system ever created by mankind, with hundreds of millions of connected computers, communication links, and switches; with billions of users who connect via laptops, tablets, and smartphones. End systems connect to Internet via access ISPs (Internet Service Providers).

  6. Internet Structure

  7. Internet structure: network of networks

  8. How many Classes of Networks? LAN: Local Area Network: Network in small geographical Area (Room, Building or a Campus). MAN: Metropolitan Area Network: Network in a City. WAN: Wide Area Network: Network spread geographically (Country or across Globe).

  9. Network Classes cont.

  10. What is a Protocol? Protocol is a rule or a set of rules set by companies, organizations or service providers to form a standard . i.e. : http TCP www FTP ………

  11. Some of the many standards bodies:

  12. 2 Kinds to Networks : Peer- to-Peer : 2 computers or more connected to each other, each node is a client and server. Clint-Server: a node(workstation, terminal) or more connected to a dedicated server . Find out the advantages and disadvantages of both types?

  13. Type of connections • Point-to-point • One-to-one communication • Unicasting • Point-to-multipoint • Communication channel shared among nodes • One-to-many • Broadcasting (ALL) • Multicasting (SOME) • Multipoint-to-point • Many-to-one

  14. Bandwidth and Latency Bandwidth is a data transmission rate; the maximum amount of information measured in bits per second (bits/second) that can be transmitted along a channel. Latency (delay) : how much time it takes for transmission from one point to another.

  15. Data communication

  16. Direction of data flow (Transmission Mode)

  17. Network Design (Topology) The network topology defines the way in which computers, printers, and other devices are connected. A network topology describes the layout of the wire and devices as well as the paths used by data transmissions. Standard Topologies:

  18. Network Devices & Elements

  19. Network Devices & Elements cont.Hub multi-port repeater (physical hardware device) provides physical star topology (but logically bus) no intelligence no separations of collision domains all the hosts compete for the shared bandwidth Active central element of star layout Each station connected to hub by two lines Transmit and receive When single station transmits, hub repeats signal on outgoing line to each station Transmission from any station received by all other stations If two stations transmit at the same time, collision

  20. Network Devices & Elementscont.Repeater: works at the Physical layer Regenerates received bits before it sends them out connects different half-duplex network segments either extends the number of users or the total span (by improving the quality of the transmitted signal) no separation of collision domains

  21. Network Devices & Elementscont.Bridge: works at layer 2 (requires software) connects two networks of the same type LAN to LAN (example: WLAN to Fast Ethernet) forwards data (1 packet @ the time) depending on the destination address in the data packet (not the IP address, but the physical (MAC) address that is unique for every Network Interface Card (NIC)) all computers are in the same sub-network packet filtering separates collision domains – larger network spans a stand alone device or a PC with the special NIC and the accompanied software can connect different Ethernet types transparent (“plug-and-play”): no configuration necessary

  22. Network Devices & Elementscont.Switch: basically a multi-port bridge provides a better network performance forwards more than a single packet at a time separates collision domains – larger total network span Incoming frame from particular station switched to appropriate output line Unused lines can switch other traffic More than one station transmitting at a time Multiplying capacity of LAN

  23. Network Devices & Elementscont. Switches Vs Hubs Hubs are half-duplex while switches are full-duplex, this means that only one station can send when connected by a hub while more than one can send when connected via a switch. And this is because: Switches separate collision domains while hubs not. A station connected with a switch can send with the maximum possible speed while with hub can send only with the speed of the slowest station speed, for example if we have many station with different speed (1, 10, and 100 mbps), if they are connected using a switch (100mbps) a two station with 100mbps speed can send with this rate while with hub they can send data only with 1 mbps.

  24. Network Devices & Elementscont.Layer 2 Switch v Bridge: Layer 2 switch can be viewed as full-duplex hub Can incorporate logic to function as multiport bridge Bridge frame handling done in software Switch performs address recognition and frame forwarding in hardware Bridge only analyzes and forwards one frame at a time Switch has multiple parallel data paths Can handle multiple frames at a time Bridge uses store-and-forward operation Switch can have cut-throughoperation Bridge suffered commercially New installations typically include layer 2 switches with bridge functionality rather than bridges

  25. Layer 2 Switch and Hub

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