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Networks

Networks. Terminology and Hardware. Network. A network is a group of connected computers that can communicate with each other to share information and equipment, such as printers. Advantages of a network. Sharing Data Reliably – without passing physical volumes, easy backup

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Networks

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  1. Networks Terminology and Hardware

  2. Network • A network is a group of connected computers that can communicate with each other to share information and equipment, such as printers.

  3. Advantages of a network • Sharing Data Reliably – without passing physical volumes, easy backup • Sharing Resources – reduces cost of buying hardware • Sharing Programs – programs can run centrally. • Communication - people can communicate and exchange messages with each other easily, effectively, and instantly. • Security Options – restricted access

  4. Networks are classified by their: • Size • Architecture • Topology

  5. Size of Networks • LAN – Local Area Network: Connects computers and devices in close proximity such as a small office or building like KRSS. • WAN – Wide Area Network: Connects a number of local area networks together over long distances (across cities, countries etc…)

  6. Architecture Configurations • Peer to Peer (p2p): People on a peer to peer network store their files on their own computers. Anyone may access files stored on any other computer. • Before the advent of TCP/IP protocols, peer to peer provided a simple and inexpensive way to connect fewer than 10 computers. (provided in Windows 98, 2000, & XP Home)

  7. Two Network Configurations • Client/Server - all files stored on a central computer. • Everyone connected to the network can access the files stored on the central server. • A Client is a computer that can access information stored on a server.

  8. Terminology Protocol – set of rules for communication Network Interface Card (NIC) – Every node is connected through an NIC – most use a 10/100 Mbps Ethernet card Node – Anything that is connected to the network (computers, printers, scanners etc…) Backbone – The main cabling of a network that all of the segments connect to. (usually faster than the connection to each NIC) Segment – Any portion of a network that is separated by a switch, bridge or router, from other parts of the network

  9. The 4 Common Wired Topologies Topology – The configuration of nodes connected to the network. • Bus – Each node is directly connected to a single central cable called a bus or backbone. • All information travels along the backbone until it reaches its destination node. • Each end must be terminated (resistor) to keep messages from bouncing back when it reaches the end of the cable.

  10. 1. Bus

  11. 2. Ring (Token Ring) • Nodes are daisy-chained. • The end of the network comes back around to the first node – completes a circuit. • Nodes take turns sending and receiving info through use of a token. • Only node with token can send info or receive info (developed by IBM).

  12. 3. Star • Star – each node is connected to a central device called a hub. The hub/concentrator takes a signal that comes from any node and passes it to all other nodes on the network.

  13. 4. Tree (Star-Bus) • The most common - combines star and bus topologies – nodes in areas are connected to hubs/concentrators (creating stars), hubs are connected together along network backbone – stars are often nested

  14. Basics of Ethernet • What it is: Currently, Ethernet is a type of wired network that connects computers and other devices. • The cables are usually copper Nodes communicate with Packets or Frames of data • Where it came from: • Originally, the material used to connect computers was ether. It was a good conductor, and it was thought that it would be less susceptible to interference. • Problem: it was too expensive

  15. Basics of Ethernet cont’d • There are practical limits to the size of the network: concerns include: • Distance limitations – electrical signals weaken as they travel. • Electrical interference scrambles signals • Practical number of devices as only one device can transmit at any given time.

  16. Ethernet Network Standards • 10BaseT • 10 Mbps • Uses UTP or CAT 5 cables • Baseband transmission – only one signal allowed on a transmission wire • 100BaseT • 100 Mbps (fast ethernet) • Use CAT5 cables – fiber optic available • Broadband – multiple signals on a single wire. • 1000BaseT – Gigabit Ethernet • 1000 Mbps - Broadband • Use CAT5e or CAT6 cables

  17. Connecting Nodes UTP - Unshielded Twisted Pair 10/100 BaseT – cheap, 100m max. STP - CAT5 – Shielded Twisted Pair – used to reduce electrical interference Coaxial Cable – must run in a ring. Fiber Optics –expensive – largest bandwidth

  18. AUI RJ45 BNC Fiber Optic 4 Types of Connectors AUI – D-shaped plug with 15 pins – common on routers and some hubs RJ45 – connectors look like big phone connectors – uses eight wires – used by most hubs and NICs BNC – small round barrel-like connectors – twist and lock together – used for coaxial Fiber Optic – usually for only one fiber optic strand

  19. CSMA/CD • CSMA/CD – Carrier Sense Multiple Access with Collision Detection • Regulates communication among nodes • Provides a “fair” set of rules for use of the line

  20. Hub (how hubs work) • Receive data • Broadcast out data on all lines • Receiving computers are responsible for listening to see if the data is for them Problems: More computers  more collisions Can’t scale more than 10 computers (Scalability) Takes more time on average for information to reach the intended node (Latency)

  21. Router (how routers work) • Receive data • Find out who the data is for • Send out data on a port that can eventually reach the intended receiver without going through a high traffic area • Keeps a table inside the router to keep track of where the high traffic areas are

  22. Switch/Bridge (how switch’s work) • LAN Switches • break hub networks into distinct segments - makes it possible for several users to send data over the network at the same time without slowing each other down • creates a series of instant networks that contain only two devices communicating with each other at that particular moment. • Nodes communicate only with the switch, so it creates a collision free environment

  23. Wireless • Bluetooth • WiFi: Wireless Fidelity - Otherwise known as Wireless Networking

  24. IEEE Standards • 802.3 – Ethernet wired standard • 802.3 is the 10 Mbps standard • 802.3u is the 100 Mbps standard • 802.3z is the 1000 Mbps standard • 802.11 – Ethernet wireless standard • 802.11b is the 11 Mbps standard • 802.11g is the 54 Mbps standard

  25. IP Address • A four part number assigned to every computer on a network • ie 192.168.1.2 • Each part of the number can be between 0-255 • A device can be manually configured to have the same address every time the device turns on • A device can be set to take an assigned number from a server or router every time it is turned on

  26. MAC Address • A six part hexadecimal number that is unique to every network card • Ie 00:02:3F:DC:75:C4 • No two network cards have the same MAC address. • The address is permanently put into the NIC at the manufacturer

  27. TCP/IP • Transmission Control Protocol/Internet Protocol • Uses IP addresses for communication • (i.e. 199.175.20.10) • Developed by ARPA (Advanced Research Projects Agency) at BB&N in 1969. • Allows for Packet Switching • Large pieces of data are broken into smaller pieces called packets • Included with each data packet is the address of the sending node and receiving devices.

  28. UDP/IP • User Datagram Protocol (UDP) • A connection-less, unreliable, transport protocol • Perfect for real time communication • Internet radio • Voice over IP (internet telephone) • Music on demand • Video conferencing • Video on demand

  29. Speeds

  30. Security • What can you do to stop someone from breaking into your system?

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