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Guide to Operating Systems, 5 th Edition

Guide to Operating Systems, 5 th Edition. Chapter 9 Configuring a Network Connection. Objectives. After completing this chapter, you will be able to: Explain the fundamentals of network communication Define common networking terms Compare and describe network device types

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Guide to Operating Systems, 5 th Edition

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  1. Guide to Operating Systems, 5th Edition Chapter 9 Configuring a Network Connection

  2. Objectives After completing this chapter, you will be able to: • Explain the fundamentals of network communication • Define common networking terms • Compare and describe network device types • Configure and describe network protocols • Describe the OSI model of networking • Configure networking in an operating system Guide to Operating Systems, 5th Edition

  3. The Fundamentals of Network Communication • A computer network consists of two or more computers connected by some kind of transmission medium • Such as a cable or air waves • In order to access the Internet, a computer has to be able to connect to a network • The next few slides will cover what is required to turn a standalone computer into a networked computer Guide to Operating Systems, 5th Edition

  4. Network Components • Hardware components needed • Network interface card (NIC)—an add-on card plugged into an expansion slot that provides a connection between the computer and the network • Network medium—A cable that plugs into the NIC and makes the connection between a computer and the rest of the network • Network media can also be the air waves, as in wireless networks • Interconnecting device—allows two or more computers to communicate on the network without having to be connected directly to one another Guide to Operating Systems, 5th Edition

  5. Network Components Figure 9-1 A network of computers connected to a switch Guide to Operating Systems, 5th Edition

  6. Network Computers • Software Components • Network clients and servers • Network client software requests information stored on another network computer or device • Network server software allows a computer to share its resources • Protocols—define the rules and formats a computer must use when sending information across the network • NIC device driver—receives data from protocols and forwards this data to the physical NIC Guide to Operating Systems, 5th Edition

  7. Steps of Network Communication 1. Application tries to access a network resource by sending a message 2. Client software formats the message and passes the message on to the network protocol 3. Protocol packages the message in a format suitable for the network and sends it to the NIC driver 4. NIC driver sends data in the request to the NIC card to be converted into necessary signals to be transmitted on the network Guide to Operating Systems, 5th Edition

  8. Layers of the Network Communication Process Figure 9-2 Layers of the network communication process Each step required for a client to access network resources is referred to as a “layer” Each layer has a task and all layers work together Guide to Operating Systems, 5th Edition

  9. Layers of the Network Communication Process Table 9-1 Layers of the network communication process Guide to Operating Systems, 5th Edition

  10. How Two Computers Communicate on a LAN • TCP/IP is the most common protocol (language) used on networks • TCP/IP uses 2 addresses to identify devices • Logical address (IP address) • Physical address (MAC address) • Just as a mail person needs an address to deliver mail, TCP/IP needs an address in order to deliver data to the correct device on a network • Think of the Logical address as a zip code and the Physical address as a street address Guide to Operating Systems, 5th Edition

  11. How Two Computers Communicate on a LAN Figure 1-7 Communication between two computers Figure 9-3 Communication between two computers Guide to Operating Systems, 5th Edition • A user at Comp A types ping 10.1.1.2 at a command prompt • Network software creates a ping message • The network protocol packages the message by adding IP address of sending and destination computers and acquires the destination computer’s MAC address • The network interface software adds MAC addresses of sending and destination computers • Comp B receives message, verifies that the addresses are correct and then sends a reply to Comp A using Steps 2 – 4

  12. How Two Computers Communicate on a LAN Table 9-2 Saving a file with the network communication process Guide to Operating Systems, 5th Edition

  13. Network Terminology Every profession has its own language and acronyms It is essential to know the language of networks to be able to study them Guide to Operating Systems, 5th Edition

  14. LANs, Internetworks, WANs, and MANs Figure 9-4 A LAN with computers interconnected by a switch Local area network (LAN) – small network, limited to a single collection of machines and connected by one or more interconnecting devices in a small geographic area Guide to Operating Systems, 5th Edition

  15. LANs, Internetworks, WANs, and MANs Figure 9-5 A wireless LAN Guide to Operating Systems, 5th Edition

  16. LANs, Internetworks, WANs, and MANs • An internetwork is a networked collection of LANs tied together by devices such as routers • Reasons for creation: • Two or more groups of users and their computers need to be logically separated but still need to communicate • Number of computers in a single LAN has grown and is no longer efficient • The distance between two groups of computers exceeds the capabilities of most LAN devices Guide to Operating Systems, 5th Edition

  17. LANs, Internetworks, WANs, and MANs Figure 9-8 An internetwork with two LANs connected by a router Guide to Operating Systems, 5th Edition

  18. LANs, Internetworks, WANs, and MANs Wide area networks (WANs) use the services of third-party communication providers to carry network traffic from one location to another Metropolitan area networks (MANs) use WAN technologies to interconnect LANs in a specific geographic region, such as a county of city Guide to Operating Systems, 5th Edition

  19. Internet, Intranet, and Extranet • Internet: a worldwide public internetwork • Uses protocols such as TCP/IP and HTTP to transfer and view information • Intranet: a private internetwork in which devices and servers are only available to those users connected to the internal network • Extranet: allows limited and controlled access to internal resources by outside users Guide to Operating Systems, 5th Edition

  20. Packets and Frames • Computers transfer information across networks in shorts bursts of about 1500 bytes of data • Reasons data is transferred this way: • If an error occurs during transmission of a large file, only the chunks of data involved in the error have to be sent again • Pause between bursts allows other computers to transfer data during pauses • Allows the receiving computer to process received data • Allows the receiving computer receive data from other computers at the same time • Gives the sending computer an opportunity to receive data from other computers and perform other processing tasks Guide to Operating Systems, 5th Edition

  21. Packets and Frames Chunks of data sent across the network are usually called packets or frames, with packets being the more well-known term Packet: a chunk of data with a source and destination IP address added to it Using the U.S. mail analogy, you can look at a packet as an envelope that has had the zip code added to the address but not the street address Guide to Operating Systems, 5th Edition

  22. Packets and Frames • Frame: a packet with the source and destination MAC addresses added to it • The packet is “framed” by the MAC addresses on one end and an error-checking code on the other • The process of adding IP addresses and MAC addresses to chunks of data is called encapsulation • Information added to the front of the data is called a header and information added to the end is called a trailer Guide to Operating Systems, 5th Edition

  23. Clients and Servers • A client can be a workstation running a client OS • Or it can refer to the network software on a computer that requests network resources from a server • The word “client” is usually used in these three contexts: • Client operating system – the OS installed on a computer • Client computer – primary role is to run user applications and access network resources • Client software – software that requests network resources from server software on another computer Guide to Operating Systems, 5th Edition

  24. Clients and Servers • A computer becomes a server when software is installed on it that provides a network service to client computers • The term “server” is also used in three contexts: • Server operating system – OS installed on a computer designed to share network resources and provide other network services • Server computer – a computer’s primary role in the network is to give client computers access to network resources and services • Server software – responds to requests for network resources from client software Guide to Operating Systems, 5th Edition

  25. Peer-to-Peer and Client/Server Networks • A network model defines how and where resources are shared and how access to these resources is regulated • Fall into two major types • Peer-to-peer network – most computers function as clients or servers (no centralized control over who has access to network resources) • Server-based network – certain computers take on specialized roles and function mainly as servers, and ordinary users’ machines tend to function mainly as clients Guide to Operating Systems, 5th Edition

  26. Peer-to-Peer and Client/Server Networks • Computers on a peer-to-peer network can take both a client and a server role • Any user can share resources on his/her computer with any other user’s computer • Every user must act as the administrator of his/her computer • Can give everyone else unlimited access to their resources or grant restricted access to other users • Usernames and passwords (credentials) are used to control that access Guide to Operating Systems, 5th Edition

  27. Peer-to-Peer and Client/Server Networks Server-based allow centralized control over network resources Users log on to the network with a single set of credentials maintained by one or more servers running a server OS In most cases, servers are dedicated to running network services and should not be used to run user applications Guide to Operating Systems, 5th Edition

  28. Peer-to-Peer and Client/Server Networks • A domain is a collection of users and computers whose accounts are managed by Windows servers called domain controllers • Users and computers in a domain are subject to network access and security policies defined by a network administrator • The software that manages this security is referred to as a directory service. • On Windows servers, the directory service software is Active Directory Guide to Operating Systems, 5th Edition

  29. Peer-to-Peer and Client/Server Networks • Other network services found on network servers: • Naming services – translate computer names to their address • E-mail services – manage incoming and outgoing email • Application services – grant client computers access to complex applications that run on the server • Communication services – give remote users access to a network • Web services – provide comprehensive Web-based application services Guide to Operating Systems, 5th Edition

  30. Peer-to-Peer and Client/Server Networks Table 9-3 Peer-to-peer versus server-based networks Guide to Operating Systems, 5th Edition

  31. Network Device Fundamentals LANs, WANs, MANs, and internetworks are built with a variety of network hardware This section covers a wide variety of network devices Guide to Operating Systems, 5th Edition

  32. Network Hubs • A multiport repeater is just a repeater with several ports to which you can connect cabling • Also referred to as a hub • Receives bit signals generated from a connected computer on one of its ports • Cleans the signal by filtering out electrical noise • Regenerates the signal to full strength • Transmits the regenerated signal to all other ports a computer (or other network device) is connected to Guide to Operating Systems, 5th Edition

  33. Network Switches • Looks just like a hub • But a switch actually reads data in the message, determines which port the destination device is connected to, and forward the message to only that port • Basic Switch Operation • Data is sent onto the medium one frame at a time • Each frame has the destination MAC address • Switch reads the addresses: • Keeps a record of which computer is on which port (switching table) • Forwards the frame to the port where the destination MAC can be found Guide to Operating Systems, 5th Edition

  34. Network Switches Figure 9-14 Switches maintain a switching table Guide to Operating Systems, 5th Edition

  35. Wireless Access Points The heart of a wireless network is the wireless access point (AP) APs operate similarly to a hub without wires All communication passes through the AP Most small business and home networks use a device typically called a wireless router that combines the functions of an AP, a switch, and a router Wireless LANs are usually attached to wired networks Guide to Operating Systems, 5th Edition

  36. Network Interface Cards • Attaching a computer to a network requires a network interface card (NIC) to create and mediate the connection between a computer and the networking medium • Networking medium might be copper wire, fiber-optic cable, or airwaves Guide to Operating Systems, 5th Edition

  37. Network Interface Cards • The tasks a NIC and its driver perform: • Provide a connection from computer to medium • Incoming messages: Receives bit signals and assembles them into frames • Verifies the destination address • Removes frame header and sends the resulting packet to the network protocol • Outgoing messages: receive packets from network protocol • Creates frames by adding MAC addresses/error check • Converts frame into bit signals suitable for the medium and transmits them Guide to Operating Systems, 5th Edition

  38. Network Interface Cards Figure 9-15 The NIC handles incoming data from the network medium Guide to Operating Systems, 5th Edition

  39. Network Interface Cards Figure 9-16 The NIC handles outgoing data to be sent to the network medium Guide to Operating Systems, 5th Edition

  40. Routers Figure 9-17 Two LANs connected by a router to make an internetwork Most complex device Connect LANs together to create an internetwork Guide to Operating Systems, 5th Edition

  41. Routers Figure 9-18 Routers interconnect LANs to form the Internet Routers are devices that enable multiple LANs to communicate with one another by forwarding packets from one LAN to another Guide to Operating Systems, 5th Edition

  42. Routers • The following are the differences between routers and switches • Routers connect LANs, switches connect computers • Routers work with logical (IP) addresses, switches work with physical (MAC) addresses • Routers work with packets, switches with frames • Routers don’t forward broadcasts, switches do • Routers use routing tables, switches use switching tables Guide to Operating Systems, 5th Edition

  43. Network Media • Unshielded Twisted Pair (UTP) – the most common media type in LANs • Consists of four pairs of copper wires twisted together and contained in a plastic sheath or jacket • Comes in numbered categories (up to Category 8) • Higher the category, the higher the bandwidth potential • Used in physical star networks • Maximum cable length from NIC to switch is 100 meters Guide to Operating Systems, 5th Edition

  44. Network Media Figure 9-19 UTP cabling Guide to Operating Systems, 5th Edition

  45. Network Media Figure 9-20 Fiber-optic cabling • Fiber-Optic Cabling • Uses thin strands of glass to carry pulses of light long distances at high data rates Guide to Operating Systems, 5th Edition

  46. Network Media • Coaxial Cable • Best known for its use in cable TV • Obsolete as a LAN medium • Used as the network medium for Internet access via cable modem Guide to Operating Systems, 5th Edition

  47. Network Protocol Fundamentals • Protocols are rules and procedures for communication and behavior • Computers must “speak” the same language and agree on the rules of communication • When a set of protocols works cooperatively it is called a protocol suite (or “protocol stack”) • The most common protocol stack is Transmission Control Protocol/Internet Protocol (TCP/IP) • TCP/IP is composed of more than a dozen protocols operating at different levels of the communication process Guide to Operating Systems, 5th Edition

  48. Network Protocol Fundamentals Figure 9-21 The TCP/IP layered architecture Guide to Operating Systems, 5th Edition

  49. Network Protocol Fundamentals • The Internetwork layer is where administrators usually do the most network configuration • Where the IP protocol operates and is the heart of the TCP/IP protocol suite • Responsible for four main tasks: • Defines and verifies IP addresses • Routes packets through an internetwork • Resolves MAC addresses from IP addresses • Delivers packets efficiently Guide to Operating Systems, 5th Edition

  50. Internet Protocol Version 4 • Internet Protocol version 4 (IPv4) or just IP • An internetwork layer protocol that provides source and destination addressing and routing for the TCP/IP protocol suite • IP addresses are 32-bit numbers divided into four 8-bit values called octets, each octet can have a value from 0 to 255 • Four decimal numbers are separated by periods in a format called dotted decimal notation • Example: 172.31.149.10 Guide to Operating Systems, 5th Edition

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