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  1. 1. Topic TwoTopic Two Network ComponentsNetwork Components (Hardware & OS)(Hardware & OS) BBC 2013/14BBC 2013/14 BWIRE SEDRICKBWIRE SEDRICK 09/24/13 1ENAM 2012
  2. 2. Network ComponentsNetwork Components • Nodes: Special purpose devices • Links: Connections between nodes 2 PC server switch bridge router Optical fiber Coaxial cable wireless09/24/13 ENAM 2012
  3. 3. Parts of a NetworkParts of a Network • Clients – Computers that request or order information from a server – Usually desktop computers with their own local storage and processing power – Thin client – network computer with no local storage 09/24/13 3ENAM 2012
  4. 4. • Servers – Computers that work behind the scenes to provide (serve) the resources requested by the clients – Two types •Non-dedicated – provides many different services to its client computers such as file retrieval, printing, and emailing •Dedicated – provides only one type of resource to its clients, such as printing 09/24/13 4ENAM 2012
  5. 5. Other network componentsOther network components • Shared peripherals – a device that is connected to a computer and controlled by its microprocessor • Media – physical pieces used to transport data from one computer to another computer or peripheral on the network • Data - packets 09/24/13 5ENAM 2012
  6. 6. Network DevicesNetwork Devices • As Organizations grow, so do their networks – Growth in number of users – Geographical Growth • Network Devices : – Are products used to expand or connect networks. – Can control the amount of traffic on a network. – Can speed up the flow of data over a network. 09/24/13 6ENAM 2012
  7. 7. Network Interface Card (NIC)Network Interface Card (NIC) • NIC provides the physical interface between computer and cabling. • It prepares data, sends data, and controls the flow of data. It can also receive and translate data into bytes for the CPU to understand. • The following factors should be taken into consideration when choosing a NIC: 1. - Preparing data 2. - Sending and controlling data 3. - Configuration 4. - Drivers 5. - Compatibility 6. - Performance 09/24/13 7ENAM 2012
  8. 8. An Ethernet NICAn Ethernet NIC 09/24/13 8ENAM 2012
  9. 9. Connectivity DevicesConnectivity Devices • Each topology and network architecture has its limits. • Beyond a point networks can not be expanded by simple adding more servers or cabling • Connectivity devices are the basic building blocks of network expansion • Are used to connect separate segments of the network or inter-network • A segment is a portion of the network transmission media that is assigned a network address • Examples: Repeaters, Hubs, Bridges & Switches 09/24/13 9ENAM 2012
  10. 10. RepeatersRepeaters • Repeaters are very simple devices. They allow a cabling system to extend beyond its maximum allowed length by amplifying the network voltages so they travel farther. • Repeaters are nothing more than amplifiers and, as such, are very inexpensive. Repeaters can only be used to regenerate signals between similar network segments. • For example, we can extend an Ethernet 10Base2 network to 400 meters with a repeater. But can’t connect an Ethernet and Token Ring network together with one. • The main disadvantage to repeaters is that they just amplify signals. These signals not only include the network signals, but any noise on the wire as well. • Operates at the physical layer of the OSI model09/24/13 10ENAM 2012
  11. 11. RepeatersRepeaters 09/24/13 11ENAM 2012
  12. 12. HubsHubs • Hubs are devices used to link several computers together. They repeat any signal that comes in on one port and copy it to the other ports (a process that is also called broadcasting). • There are two types of hubs: active and passive. • Passive hubs simply connect all ports together electrically and are usually not powered. • Active hubs use electronics to amplify and clean up the signal before it is broadcast to the other ports. • In the category of active hubs, there is also a class called “intelligent” hubs, which are hubs that can be remotely managed on the network. 09/24/13 12ENAM 2012
  13. 13. HubsHubs 09/24/13 13ENAM 2012
  14. 14. BridgesBridges • They join similar topologies and are used to divide network segments. • For example, with 200 people on one Ethernet segment, the performance will be mediocre, because of the design of Ethernet and the number of workstations that are fighting to transmit. If you divide the segment into two segments of 100 workstations each, the traffic will be much lower on either side and performance will increase. • If it is aware of the destination address, it is able to forward packets; otherwise a bridge will forward the packets to all segments. They are more intelligent than repeaters but are unable to move data across multiple networks simultaneously. • Unlike repeaters, bridges can filter out noise. • The main disadvantage to bridges is that they can’t connect dissimilar network types or perform intelligent path selection. For that function, you would need a router. 09/24/13 14ENAM 2012
  15. 15. BridgesBridges A bridge is a Layer 2 (Data Link Layer) device. 09/24/13 15ENAM 2012
  16. 16. RoutersRouters • Routers are highly intelligent devices that connect multiple network types and determine the best path for sending data. • The advantage of using a router over a bridge is that routers can determine the best path that data can take to get to its destination. • Like bridges, they can segment large networks and can filter out noise. • However, they are slower than bridges because they are more intelligent devices; as such, they analyze every packet, causing packet-forwarding delays. Because of this intelligence, they are also more expensive. • Routers are normally used to connect one LAN to another. Typically, when a WAN is set up, there will be at least two routers used. • Internetwork connectivity device 09/24/13 16ENAM 2012
  17. 17. RoutersRouters 09/24/13 17ENAM 2012
  18. 18. SwitchSwitch • A network switch is a computer networking device that connects network segments. • Low-end network switches appear nearly identical to network hubs, but a switch contains more "intelligence" (and a slightly higher price tag) than a network hub. • Network switches are capable of inspecting data packets as they are received, determining the source and destination device of that packet, and forwarding it appropriately. • By delivering each message only to the connected device it was intended for, a network switch conserves network bandwidth and offers generally better performance than a hub. • A vital difference between a hub and a switch is that all the nodes connected to a hub share the bandwidth among themselves, while a device connected to a switch port has the full bandwidth all to itself. • For example, if 10 nodes are communicating using a hub on a 10-Mbps network, then each node may only get a portion of the 10 Mbps if other nodes on the hub want to communicate as well. But with a switch, each node could possibly communicate at the full 10 Mbps. 09/24/13 18ENAM 2012
  19. 19. SwitchSwitch 09/24/13 19ENAM 2012
  20. 20. GatewaysGateways • A gateway is a network point that acts as an entrance to another network. On the internet, in terms of routing, the network consists of gateway nodes and host nodes. • Host nodes are computer of network users and the computers that serve contents (such as Web pages). • Gateway nodes are computers that control traffic within your company’s network or at your local internet service provider (ISP) • Internetwork connectivity device 09/24/13 20ENAM 2012
  21. 21. Security DevicesSecurity Devices • Increased Internet and extranet connections • More telecommuters • Mobile users • Security Devices: – Firewalls: •Software or Hardware •Only valid traffic can enter or leave the network – AAA Servers •Authentication, Authorization, and Accounting Servers – VPN Concentrators •Remote access and site-to site VPN capabilities 09/24/13 21ENAM 2012
  22. 22. Wireless DevicesWireless Devices • Wireless NICs – Provide wireless connectivity – PCMCIA and PCI cards to provide • Wireless Access Points – It is a wireless LAN transceiver – Acts as a hub or as a bridge – Multiple Access Points – Roaming Functionality • Wireless Bridges – Provide long-range connectivity – 25 miles – Line of sight wireless09/24/13 22ENAM 2012
  23. 23. Wireless LAN TopologyWireless LAN Topology 09/24/13 23ENAM 2012
  24. 24. 24 •Allow computers to communicate over a telephone line •Enable communication between networks or connecting to the world beyond the LAN •Cannot send digital signal directly to telephone line •Sending end: MODulate the computer’s digital signal into analog signal and transmits •Receiving end: DEModulate the analog signal back into digital form Modems Remote Access devicesRemote Access devices 09/24/13 ENAM 2012
  25. 25. Communication MediaCommunication Media • A path through which information are transmitted from one place to another is called communication media. It is also referred to as communication medium or link. • In network communication, the communication media’ are wires, cables and other means through which information travels from its source to its destination. ENAM 201209/24/13 25
  26. 26. Features of a communication MediaFeatures of a communication Media • Transmission speed (measured in bps) • Band width (capacity of communication media, measure is Hertz or bps) • Transmission mode –Asynchronous transmission –Synchronous transmission • Transmission direction • Simplex • Half duplex • Full-duplex ENAM 201209/24/13 26
  27. 27. Con’tCon’t • Data is transmitted in the form of signals (analog signal). • The data transmission is measured in bandwidth. • Bandwidth measures the amount of information that can be transmitted through the media within the given period of time. • For analog signals bandwidth is represented in hertz (Hz). • For digital signals, it is represented in bits per second (bps). • The higher the bandwidth of the transmission media, the more information can be transmitted. ENAM 201209/24/13 27
  28. 28. Asynchronous and SynchronousAsynchronous and Synchronous transmissiontransmission • Asynchronous transmission is where data is transmitted one character at a time, where each character is five to eight bits in length. • The most common transfer rates in these are btn 1200 & 19200 bits per second. • This is used mainly to transfer medium quantities of data over a long distances. 09/24/13 28ENAM 2012
  29. 29. Synchronous transmissionSynchronous transmission • Synchronous transmission is a mode of transmission where data is transferred in a block of bits at ago without a start and stop. • It is amore efficient mode of transfer used mainly to transfer large quantities of data e.g. contents in disk already assembled. 09/24/13 29ENAM 2012
  30. 30. Transmission directionTransmission direction • Simplex transmission: Where by data can travel in only one direction at all times. • These systems are often employed in broadcast networks, where the receivers do not need to send any data back to the transmitter/broadcaster. eg radio stations and TV 09/24/13 ENAM 2012 30
  31. 31. Half-duplexHalf-duplex • A half-duplex system allows communication in both directions, but only one direction at a time (not simultaneously). • Any radio system where you must use "Over" to indicate the end of transmission, or any other procedure to ensure that only one party broadcasts at a time would be a half duplex. 09/24/13 31ENAM 2012
  32. 32. Full-duplexFull-duplex • A full-duplex system allows communication in both directions, and unlike half-duplex allows this to happen simultaneously. • Most telephone networks are full duplex as they allow both callers to speak at the same time. • A good analogy for a full-duplex system would be a two lane road with one lane for each direction. Example: Telephone, Mobile Phone, etc. 09/24/13 32ENAM 2012
  33. 33. Classes of Transmission MediaClasses of Transmission Media 09/24/13 ENAM 2012 33
  34. 34. 7.34 GUIDED MEDIAGUIDED MEDIA Guided media: Are those that provide a conduit from oneGuided media: Are those that provide a conduit from one device to another, include twisted-pair cable, coaxialdevice to another, include twisted-pair cable, coaxial cable, and fiber-optic cable.cable, and fiber-optic cable. 09/24/13 ENAM 2012
  35. 35. 35 Twisted Pair WireTwisted Pair Wire •Two or more pairs of single conductor wires that have been twisted around each other. •Twisted pair wire is classified by category. Twisted pair wire is currently Category 1 through Category 6. •Twisting the wires helps to eliminate electromagnetic interference between the two wires. •Shielding can further help to eliminate interference. •Two types; shielded and Un shielded twister pair wire •It uses RJ 45 connectors 09/24/13 ENAM 2012
  36. 36. 36 Coaxial CableCoaxial Cable A single wire wrapped in a foam insulation surrounded by a braided metal shield, then covered in a plastic jacket. Cable can be thick or thin. Baseband coaxial technology uses digital signaling in which the cable carries only one channel of digital data. Broadband coaxial technology transmits analog signals and is capable of supporting multiple channels of data. 09/24/13 ENAM 2012
  37. 37. Coaxial CableCoaxial Cable • Coaxial cable is also referred to as Coax. It carries signals of higher frequency ranges than twisted-pair cable. • Coaxial cable can be used for telephone lines for voice and data transmission with very high frequency. The bandwidth of coaxial cable is 80 times greater than twisted pair media, Coaxial cable is also widely used in local area network (LAN). It is more expensive than twisted-pair wire. • It creates less noise and protects the cable from interference of external electromagnetic waves. Has low transmission error rates. • These cables can transmit data over longer distances than that of twisted pair. Transmission speed is from 10 Mbps to 200 Mbps. ENAM 201209/24/13 37
  38. 38. 38 Fiber Optic Cable •A thin glass cable approximately a little thicker than a human hair surrounded by a plastic coating and packaged into an insulated cable. A fiber optic cable consists of tubes of glass (or thin glass fibers) through which data is transmitted as pulses of light. The core is surrounded by a concentric layer of glass called Cladding •The data transmission speed is very high because fiber-optic cable uses light to transmit data. Transmission speed is up to billions bits per second. •It has high level of security. •It is not affected by electromagnetic waves. •It is more reliable and has lower data transmission errors. Disadvantages •It is more costly. •It is difficult to install and modify 09/24/13 ENAM 2012
  39. 39. 39 It is very common to mix fiber with twisted pair in LANs. 09/24/13 ENAM 2012
  40. 40. 40 Data Communications and Computer Networks Chapter 3 09/24/13 ENAM 2012
  41. 41. 41 Radio, satellite transmissions, and infrared light are all different forms of electromagnetic waves that are used to transmit data. •LANs use radio waves •WANs use microwave signals Wireless Media 09/24/13 ENAM 2012
  42. 42. 42 •Land-based, line-of-sight transmission •Approximately 20-30 miles maximum between towers •Transmits data at hundreds of millions of bits per second •Popular with telephone companies and business to business transmissions Terrestrial Microwave 09/24/13 ENAM 2012
  43. 43. 43 Similar to terrestrial microwave except the signal travels from a ground station on earth to a satellite and back to another ground station. Satellites can be classified by how far out into orbit each one is (LEO, MEO, GEO, and HEO). Satellite Microwave 09/24/13 ENAM 2012
  44. 44. 44 Data Communications and Computer Networks Chapter 3 09/24/13 ENAM 2012
  45. 45. 45 •LEO - Low Earth Orbit - 100 miles to 1000 miles. Used for pagers, wireless e-mail, special mobile telephones, spying, videoconferencing. •MEO - Middle Earth Orbit - 1000 to 22,300 miles. Used for GPS and government. •GEO - Geosynchronous Orbit - 22,300 miles. Used for weather, television, and government operations. •HEO – Highly Elliptical Orbit A fourth type of orbit used by the military for spying and by scientific organizations for photographing celestial bodies. When satellite is far out into space, it takes photos. When satellite is close to earth, it transmits data. Satellite Microwave 09/24/13 ENAM 2012
  46. 46. 46 Mobile TelephoneMobile Telephone Wireless telephone service, such as cellular telephone and PCS (personal communication system). To support multiple users in a metropolitan area (market), the market is broken into cells. Each cell has its own transmission tower and set of assignable channels. 09/24/13 ENAM 2012
  47. 47. 47 (MTSO) Mobile Telephone Switching Office 09/24/13 ENAM 2012
  48. 48. 48 Special transmissions that use a focused ray of light in the infrared frequency range. Very common with remote control devices, but can also be used for device-to-device transfers, such as PDA to computer. Bluetooth is a Radio Frequency specification for short-range, point-to-multipoint voice and data transfer. Bluetooth can transmit through solid, non-metal objects. Its typical link range is from 10 cm to 10 m, but can be extended to 100 m by increasing the power. Infrared & Bluetooth Transmissions 09/24/13 ENAM 2012
  49. 49. 49 This technology transmits data between workstations and local area networks using high speed radio frequencies. Current technologies allow up to 54 Mbps data transfer at distances up to hundreds of feet. Wireless LAN (IEEE 802.11) 09/24/13 ENAM 2012
  50. 50. 50 •Cost – Initial, maintenance/support cost •Speed – Data transfer, propagation speed •Distance and expandability •Environment – Noise level •Security – Wiretap possible? Need encryption? Communication Media Selection CriteriaCommunication Media Selection Criteria 09/24/13 ENAM 2012