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Understanding LAN Networks: Basics & Architectures

Learn about LAN transmission media, physical and logical topologies, OSI Model, advantages of peer-to-peer and client/server networks, and different types of computer networks for e-business technologies.

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Understanding LAN Networks: Basics & Architectures

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  1. Chapter 2 Networking Basics E-Business Technologies

  2. Objectives In this chapter, you will learn to: • Illustrate the different types of computer networks • Describe LAN transmission media • Discuss physical and logical LAN topologies • Explain the network services provided by LANs • Identify standards organizations and their role in setting standards • Describe the Seven-Layer OSI Model E-Business Technologies

  3. Valued Gateway Client: Types of Computer Networks • A computer network consists of: • Two or more computers, as well as • Other devices such as printers or faxes connected by some form of data transmission media such as a cable • Network Operating Systems provide network services including: • File management • Security • Resource management • Computers and network devices use a Network Interface Card to connect with the network E-Business Technologies

  4. Local Area Networks (LANs) LANs • Are limited to a small geographic area, such as an office or a building - will not use the public telephone system • Have two basic architectures • Peer-to-peer • Client/server • Each computer has its own processing capabilities, but can access files on other computers, network printers, and use network services • Each computer or destination device on the network is also known as a node - nodes are 'self aware' of the network(s) to which they belong what's the difference? and why do you care? E-Business Technologies

  5. Peer-to-Peer Networks • Usually consist of six or fewer general-purpose personal computers • Computers communicate with each other and share the same files and devices • Every computer on a peer-to-peer network is equal, that is, no one computer is in charge of the other computers • Does not require a special Network Operating System - but note that microcomputer operating systems since Windows 2000 and Windows XP incorporate network capabilities E-Business Technologies

  6. Peer-to-Peer Network • All computers are connected to one main cable (also called the backbone) • Simplest option when connecting two or three devices what happens if the backbone breaks? E-Business Technologies

  7. Peer-to-Peer Network with a Hub • All computers are connected through a common connection point (Hub) • Can connect more computers and devices to a network than a backbone • can be 'daisy chained' but this is inefficient E-Business Technologies

  8. Peer-to-Peer Network with a Hub E-Business Technologies

  9. ADVANTAGES Simple and inexpensive network solution Does not require special Network Operating System Simplicity of administration DISADVANTAGES Not practical for more than five or six computers Limited or no security Business may quickly outgrow network Peer-to Peer NetworkAdvantages/Disadvantages E-Business Technologies

  10. Client/Server Network • Consists of general-purpose personal computers which are called clients and special high-performance computers called servers - there is no special need for the 'server' to have any more or less power than the clients • Servers enable clients to: • share data • store data • provide support for network services, such as e-mail • Requires a special network operating system such as Microsoft Windows 2000 Server, UNIX, or Novel NetWare (Novel has a smaller part of today's market of network operating systems) E-Business Technologies

  11. Client/Server NetworkArchitecture E-Business Technologies

  12. ADVANTAGES Centralizes management of network services in one location Increased security Support for greater number of computers, devices DISADVANTAGES Requires more complex setup and management Administration requires higher level of technical expertise More expensive to implement Client/Server NetworkAdvantages/Disadvantages E-Business Technologies

  13. few people use the term "MAN" anymore, it is just a 'longer' LAN that does note interface with the public telephone system Metropolitan Area Network (MAN) • A high-speed network connecting two or more LANs • A MAN is usually confined to a single metropolitan area, such as a large city and its suburbs E-Business Technologies

  14. Wide Area Network (WAN) • Spans a larger area than a MAN and consists of two or more connected LANs • The Internet is a very complex and extensive WAN E-Business Technologies

  15. LAN Transmission Media • Transmission media are the means for carrying data from one node on a LAN to another node • Transmission media is divided into two types: • Cable • Wireless E-Business Technologies

  16. Coaxial Cable (coax) • High-capacity communications and video cable • Has an insulated solid or stranded wire surrounded by a solid or braided metallic shield, wrapped in a plastic cover • Carries heavy network traffic at high speeds • Provides resistance to interference called “noise” E-Business Technologies

  17. Twisted-Pair Cable • Consists of insulated copper wires twisted around each other in pairs and then enclosed in a plastic covering • Two most common types are shielded and unshielded • By far the most prevalent medium today for LANs E-Business Technologies

  18. Fiber-optic Cable • Used to carry voice, video, and data signals for very long distances without requiring 'repeaters' • Contains one or more glass fibers at its core, surrounded by a layer of glass cladding and a protective outer jacket E-Business Technologies

  19. incorrect representation, should be four groups of twisted pairs for 8 total wires E-Business Technologies

  20. Infrared (IR) Transmission • Relies on electromagnetic waves with a frequency range above that of microwave but below the visible spectrum • solid objects block the transmission • Infrared signals are transmitted through space in the same way a TV remote control device sends signals across a room E-Business Technologies

  21. Radio Frequency (RF)Transmission • Relies on signals sent over a specific frequency, like radio broadcast • not blocked by solid objects (but a solid object lessens signal strength) • RF transmissions are regulated by the Federal Communications Commission (FCC) which licenses frequencies by geographic location to ensure that multiple transmitters do not interfere with each others’ transmissions E-Business Technologies

  22. E-Business Technologies

  23. Traveling at the Speed of Data • Throughput – Amount of data that can be transmitted within a specific time period • Measured in units of bits per second (bps) • 1 Kbps = 1,000 bits per second • 1 Mbps = 1,000,000 bits per second = 1,000Kbps • 1 Gbps = 1,000,000,000 bits per second = 1,000 Mbps • Throughput for most (Ethernet) networks is between 10 Mbps and 100 Mbps • Current media (category 7 twisted pair) runs 1Gbps (i.e. 1,000Mbps) with 10Gbps available but network interface cards of 10/100Mbps are the most common E-Business Technologies

  24. Physical Topologiesof Local Area Networks • Physical topology refers to a network’s physical layout or the pattern in which its devices and cabling are organized • Three basic physical topologies: • Bus • Ring • Star • Modern LANs generally combine these topologies into a hybrid topology E-Business Technologies

  25. Bus Topology • Used on peer-to-peer LANs • Consists of a single coaxial cable called a trunk (or backbone) to which all devices are connected • Because the cable is shared, it carries only one transmission at a time E-Business Technologies

  26. Data Transmissions • Data transmissions involving one sending and receiving node are called point-to-point transmissions • Transmissions that involve one sending node and multiple receiving nodes are called broadcast transmissions E-Business Technologies

  27. Ring Topology • Each node is connected to the next node via a single circle of twisted-pair or fiber-optic cable • Data transmissions travel around the circle in a clockwise direction, passing through each node • When a node receives a transmission, it accepts the data addressed to it and then forwards the transmission on to the next node E-Business Technologies

  28. Star Topology • Each node is connected to a central hub by a separate twisted-pair or fiber-optic cable • Data is transmitted from one node, through the hub, and out again to the destination node E-Business Technologies

  29. Hybrid Topology • Contains elements of two or more physical topologies • Star-wired ring topology is the most common hybrid • Data travels in a circle, from one node to the next, but each transmission passes through the hub E-Business Technologies

  30. Logical Topologiesof Local Area Networks • Logical topology defines the way in which the data is transmitted between computers • Specifies several network characteristics including: • The access methods, or rules, the nodes follow to access the transmission media • The network’s physical topology • The network’s transmission media • The data throughput rate • Logical topologies commonly used on LANs are Ethernet and Token Ring (actually, token ring is much less common) E-Business Technologies

  31. Ethernet • Uses Carrier Sense Multiple Access with Collision Detection (CSMA/CD) access method, which directs transmission traffic over the network • All stations attached to the Ethernet are "listening" and the station with the matching destination address accepts the frame and checks for errors • Collisions: • If two nodes simultaneously check and then transmit, their two transmissions collide • In this case, both nodes immediately stop transmitting, wait a random interval, recheck, and then rebroadcast E-Business Technologies

  32. Token Ring • A network access method that uses a continuously repeating 3-byte frame (the token) that is transmitted onto the network by the controlling computer • The token moves clockwise in a circle from node to node • When a node wants to send a message, it waits for an empty token; then fills it with the address of the destination node and some or all of its message • Every node on the network constantly monitors passing tokens to determine if it is the recipient of a message, in which case it "grabs" the message and resets the token status to empty E-Business Technologies

  33. Network Services • Programs that manage data and operations on a network, and provide services to multiple users • Network services include: • File services • Print services • Mail services • Communications services • Internet services • Management services E-Business Technologies

  34. File Services • Permit centralized storage of data files • A high-speed computer in a network stores the programs and data files shared by users • A file server acts like a remote disk drive • Data stored on a file server can be accessed by authorized users around the network E-Business Technologies

  35. Print Services • Enable employees to share printers across a network • Print services include storing print-image output from all users of the system and feeding it to the printer one job at a time • A print server provides this service for one or more printers in a network • The print server function may be software that is part of the network operating system or an add-on utility E-Business Technologies

  36. Using NetworkFile and Print Services • Document is created and stored on the file server • Second user can retrieve document from file server then edits and saves file on the file server • Remote user can retrieve document from file server • Sends document to network printer E-Business Technologies

  37. Mail Services • Manages the sending, receiving, routing, and storage of e-mail • Controlled by a mail server, usually a computer in a network that provides "post office" facilities • Mail services include storing incoming mail for distribution to users and forwarding outgoing mail through the appropriate channel • The software that performs this service may reside on a computer providing other services E-Business Technologies

  38. Communications Services • Enables traveling employees (remote users) to connect to the network and access their data files and e-mail messages • Company LAN is accessed using POTS (plain, old telephone system) or ISDN modem, or broadband connection through a remote access server, or wireless, or any other communications medium E-Business Technologies

  39. Using NetworkMail and Communications Services • User e-mails a document to a co-worker for editing • Second user edits the document, then e-mails copy to the remote user • Remote user connects to network, then retrieves document from e-mail • Remote user edits document, then e-mails document to the original user E-Business Technologies

  40. Internet Services • Provides external Internet access, internal intranet services, and management of Internet-related technologies such as Web servers, Web browsers, and Internet-based e-mail • Used to establish and manage external business Web sites to sell products and services, provide customer support, and gather information about potential customers and the marketspace • Internet-based e-mail allows businesses to maintain contact with customers and suppliers E-Business Technologies

  41. Network Management Services • Enables administrator to monitor network activity, manage user access and network resources • Includes diagnostic and management tools for troubleshooting problems and gathering statistics for administration and fine tuning • Centralized installation of software and backup of stored data E-Business Technologies

  42. The Role of Standards Organizations • A standard is a rule, description, or design approved by an established organization or accepted by an industry through common usage • Networking standards that cover the formatting and transmission of data are set by third-party organizations that include government agencies, scientists, research institutions, consumer groups, engineers, manufacturers, vendors, and other interested parties E-Business Technologies

  43. International Organization for Standardization (ISO) • A global alliance drawn from approximately 140 countries • Establishes and publishes standards that help make possible the international trade of goods and services • Standards govern areas such as: photographic equipment and film speed, quality management, environmental management, freight container, and paper size E-Business Technologies

  44. International Electrotechnical Commission (IEC) • Promote international standards in fields of electronics, magnetics and electromagnetics, electroacoustics, multimedia, and telecommunications • Works with ISO to develop standards for the IT industry ANSI - American National Standards Institute • Non-profit organization that represents the U.S. to international organizations such as ISO and IEC • Promotes adoption of U.S. and international standards that make U.S. businesses more competitive in global markets E-Business Technologies

  45. Electronic Industries Alliance (EIA) Develops standards for electronic components, consumer electronics, and telecommunications Institute of Electrical and Electronics Engineers, Inc. (IEEE) Internal authority on biomedical technology, consumer electronics, computer engineering, electric power, aerospace, and telecommunications Additional Standards Organizations E-Business Technologies

  46. International Telecommunications Union (ITU) International forum for government agencies and industry representatives Develops standards for telecommunications European Telecommunications Standards Institute (ETSI) European standards organization in the areas of telecommunications, broadcasting, and information technology Additional StandardsOrganizations E-Business Technologies

  47. Open Systems Interconnection(OSI) Model • An ISO standard for worldwide communications that defines a framework for implementing protocols in seven layers • Control is passed from one layer to the next, starting at the application layer in one station, proceeding to the bottom layer, over the channel to the next station and back up the hierarchy E-Business Technologies

  48. Open Systems Interconnection(OSI) Model hubs are at level 1, routers act at level 3, switches act at levels 2 & 3 7 6 5 4 3 2 1 7 6 5 4 3 2 1 E-Business Technologies

  49. SENDING NODE Passes bits onto the connecting medium RECEIVING NODE Receives bits from the connecting medium Physical Layer (1) • Defines the physical and electrical characteristics of a system E-Business Technologies

  50. SENDING NODE Subdivides data into frames, and then transfers without errors Retransmits frames if acknowledgement is not received RECEIVING NODE Reassembles the frames, performs error checking, then acknowledges receipt of the data Data Link Layer (2) • Ethernet technologies work at the Data Link layer E-Business Technologies

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