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Building a Network: Topology and Protocols

Building a Network: Topology and Protocols. Chapter 4. Chapter Objective. Understand network connectivity. Peer-to-Peer network & Client-Server network Understand network topology Star, Bus & Ring topology Understand congestion control techniques Network equipment .

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Building a Network: Topology and Protocols

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  1. Building a Network: Topology and Protocols Chapter 4

  2. Chapter Objective • Understand network connectivity. • Peer-to-Peer network & Client-Server network • Understand network topology • Star, Bus & Ring topology • Understand congestion control techniques • Network equipment Prepared by Saher H. Mohammed

  3. Network Connectivity Basics • The arrangement of nodes (hosts, machines, computers, printers, etc.) is called topology. • The way the networks are arranged, constructed is called topology. Node 1 Node 2 • This is called a n = 2 network • If both the nodes are computers, then it is called a point-to-point network Prepared by Saher H. Mohammed

  4. Network Connectivity Basics • Network consist of two or more nodes, connected by one or more channels. • When many computers and peripherals are connected to a common communication channel, it is called a multi-point network or multi-node network. Node 1 Node 2 Node 3 Node 4 Printer Prepared by Saher H. Mohammed

  5. Relationship between Nodes • Any devices such as a hard disk or printer that are accessed and used by all the nodes on the network are called shared resources. • Two kinds of relationship exist between the connected nodes • Peer-to-Peer network. • Cooperative processing. • Distributed processing. • Client – Server network. Prepared by Saher H. Mohammed

  6. Peer-to-Peer network • In a Peer-to-Peer network, all the computers in the network are of same standing (level) and neither is a master or a slave (Server-Client). • A way to enhance the use of resources is cooperative processing, the sharing of processing tasks between two or more processors, either within or between computers. • Distributed processing is the dispersion of the data processing among computers in multiple sites. Prepared by Saher H. Mohammed

  7. Client – Server Architecture • In Client - Server relationship, the nodes are not equal. One node is the Server (master) and the rest of the nodes are Clients (slave). • All the clients request service from the server, such as file space, common printer, and shared processing. Prepared by Saher H. Mohammed

  8. Client – Server Architecture Client Client Client Hub Server Client Client Prepared by Saher H. Mohammed

  9. Client – Server Architecture • In the client – server architecture, if the clients have no storage nor the processing capabilities, then the clients are called dumb terminal. • Example old mainframes systems. • In current client – server architecture, most of the clients have processing capabilities. Prepared by Saher H. Mohammed

  10. Client – Server Architecture • The client – server architecture is the basis for the current day Local Area Networks and Wide Area Network. • In client – server architecture, the client can be of two types • Thin Client – they have very limited processing and storage capabilities. • Example – Smart phones. • Fat Client – they have large storage and processing capabilities. • Example – Desktop and Laptops. Prepared by Saher H. Mohammed

  11. Client – Server Architecture Client - Desktop Client - IPad Client - Laptop Hub Server Client – Smart phone Client - Laptop Prepared by Saher H. Mohammed

  12. Client – Server Architecture • Advantages • Resource sharing. • Share processing. • Easy maintenance. Prepared by Saher H. Mohammed

  13. Components of a Network • Network Operation systems • Example Microsoft Windows 2003/2008 Server OS. • A networking device • Hub, Switch, Router. • Network Interface Card (NIC) • Media (Wire) Prepared by Saher H. Mohammed

  14. Toplology • Geographical arrangement of a network’s components is also called a topology. • Topology can be of two types • Physical Topology – how the wiring is laid out. • Electrical Topology – how the nodes use the path. Prepared by Saher H. Mohammed

  15. Star Topology • The most common type of the network topology. • All the cables from the end nodes (clients and server) are connected to a central point – Hub or a Switch. Client Client - PC Hub Active Node Client Client Client - PC Client - Laptop Server Client Client - Scanner Client - Printer Prepared by Saher H. Mohammed

  16. Star Topology • In the star topology, the end nodes acquire the attention of the central node before communication can take place, this process is called polling. • One disadvantage of star topology is congestion. • If the central active node is busy, then the network becomes congested. Prepared by Saher H. Mohammed

  17. Bus Topology • In a bus topology, all the nodes are connected to a single, central wire called as bus. • One major drawback of a bus topology is the single point of failure. • If the central wire fails, then the entire network breaks down. Prepared by Saher H. Mohammed

  18. Bus Topology Client Client Client Server Client Prepared by Saher H. Mohammed

  19. Ring Topology • In the ring topology, each node is connected to the one above node and the one below node. • All the messages pass around the ring and each transmitted node will see part of the message. • In order to transmit, a node must possess a token. • At any time, only one node can have a token. Prepared by Saher H. Mohammed

  20. Ring Topology Client Client Client Server Client Client Prepared by Saher H. Mohammed

  21. Collision Control • Collision occurs when two or more nodes transmit at the same time. • Collision can make all the communication in the network to stop. • There are two methods of collision control • Collision Avoidance. • Collision Detection. Prepared by Saher H. Mohammed

  22. Collision Avoidance – Star Topology • In a star topology, all the end nodes are connected to a central node. So, before communicating, the end nodes must get the attention of the central node – polling. • Central node will poll/ query all the end nodes to check if some end node is ready to transmit or the central node is ready to receive any message from the end nodes. • The end nodes will poll/ query the central node to signal that they are ready to transmit, and will wait till the central node is ready. Prepared by Saher H. Mohammed

  23. Collision Avoidance – Ring Topology • Only one node in the ring topology will have the token, only that node will have the permission to send the messages. • Once the node is finished with sending the message, it will release the token for the other nodes to use. • In the ring topology, messages are passed from one node to the next until the messages reaches the destination. Prepared by Saher H. Mohammed

  24. Collision Detection – Bus Topology • Collision detection – react to the collisions, instead of avoiding it. • The bus topology uses carrier sense multiple access/ collision detection (CSMA/ CD). • Carrier sense is the primary way of gaining the access to the central wire/ bus. Prepared by Saher H. Mohammed

  25. Collision Detection – Bus Topology • The node willing to transmit will sense the carrier (central wire). If there are no signals on the carrier, the node will broadcast the message. • All the nodes in the network will get the message, but only the correct recipient will be able to access the message. Prepared by Saher H. Mohammed

  26. Network Equipments • To build a network, certain networking devices are used • Repeater. • Hub. • Switch. • Router. • Gateway. • Bridge. Prepared by Saher H. Mohammed

  27. Repeater • A repeater is a simple hardware device that receives a weak signal and regenerates it. • Since the repeater creates a new signal, the distortion or attenuation is removed and the signal is made stronger. • Repeaters are used at Layer 1( Physical) of the OSI Model. • Repeaters are generally used to extend the coverage of a network by extending the length of the segment. Prepared by Saher H. Mohammed

  28. Repeater Prepared by Saher H. Mohammed

  29. Hub • A hub is a hardware device that physically connects multiple cables, providing a common connection point. • Hubs are passive devices. They will forward a message to all the nodes connected via the ports. • Hubs will divide the bandwidth among all the nodes. • Hubs are used at Layer 1( Physical) of the OSI Model. Prepared by Saher H. Mohammed

  30. Hub Prepared by Saher H. Mohammed

  31. Switch • A switch is a special type of hub. • A switch is an active device. • Switch operates at the second layer (DLL) of OSI model. • A switch will forward the packets only the correct destination. • A switch will not divide the bandwidth, thus the transmission speed is higher. Prepared by Saher H. Mohammed

  32. Switch Prepared by Saher H. Mohammed

  33. Bridges • A bridge is software or a hardware device that connects two LAN’s or two segments of the same LAN. • Bridge is a layer 2 (DLL) device. • Two LAN’s or the two segments of the same LAN must use the same data link protocol. • Example (Ethernet, Token, Ring) Prepared by Saher H. Mohammed

  34. Bridges Types • Transparent Bridge: Connects two LAN’s that use the same data link protocol. • Ethernet network– Ethernet network. • Token ring network – Token ring network. • Translating Bridge: Connects two LAN’s that use different data link protocol. • Ethernet network– Token ring network. • Token ring network – Ethernet network. Prepared by Saher H. Mohammed

  35. Bridges Prepared by Saher H. Mohammed

  36. Router • Routers are hardware devices used to forward the data packets between different networks. • Routers intelligent devices, they have routing protocols and store the path information in the routing tables. • Routers operate at the third layer (Network) of OSI model. Prepared by Saher H. Mohammed

  37. Routers • Routers can be static or dynamic. • Static – the routing table cannot be changes. • Dynamic – the routing table can change depending on the situation to find the next best route. Prepared by Saher H. Mohammed

  38. Router Prepared by Saher H. Mohammed

  39. Gateways • A gateway is a node on a network that serves as an entrance to another network. • Gateway is a device that uses software to connect networks with different architecture by performing protocol conversion at the application level. • Gateway operates at all the 7 layers of the OSI Model. Prepared by Saher H. Mohammed

  40. Gateways Prepared by Saher H. Mohammed

  41. OSI Levels of Network Devices Prepared by Saher H. Mohammed

  42. Comparison Going up from switches – Routers – Gateways, the capabilities, complexities and the cost increases. Prepared by Saher H. Mohammed

  43. A Complete Network Prepared by Saher H. Mohammed

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