Network Connectivity

1
Network Connectivity

• Guide to Operating Systems
• Third Edition

2
Objectives

• After reading this chapter and completing the
  exercises you will be able to
• Explain networking basics
• Describe network transport and communications
  protocols
• Explain how to integrate different operating
  systems on the same network
• Describe how operating systems are used for
  remote networking

3
Networking Basics

• Network
• system of computing devices, computer resources,
  information resources, and communication devices
• linked with cables or wirelessly
• The basic principle of networking is similar to
  connecting telephones for communications

4
Networking Basics (continued)

• Hardware
• computers, printers, communications cable
• internetworking devices such as bridges,
  switches, routers, and hubs
• Software
• client and server network operating systems

5
Networking Basics (continued)

• Client operating system
• run applications, process information, and
  communicate over the network
• Windows 98, Windows NT 4.0 Workstation, Windows
  2000 Professional, and Windows XP Professional

6
Networking Basics (continued)

• Workstation
• CPU and can run applications locally, or obtain
  applications and files from another computer on
  the network
• Terminal
• no CPU or local storage for running programs
  independently

7
Networking Basics (continued)

• Server Operating System
• network operating system (NOS) that coordinates
  network activities and the sharing of resources
• Remote Installation Services (RIS)
• install pre-configured client operating systems,
  such as Windows XP, on a mass scale

8
Networking Basics (continued)

• Publishing an application
• installing custom configured software from a
  central server
• Assigning applications
• Enables a client to automatically start a
  particular version of software through a desktop
  shortcut or menu selection, or by clicking a file
  type

9
The Development of Network Operating Systems

• UNIX
• first operating system designed for networks
• Novell NetWare
• one of first commercial operating system to
  emphasize network capabilities

10
The Development of Network Operating Systems
(continued)

• Windows 3.11
• Windows for Workgroups (WFW)
• connects to NetWare, Microsoft, and other servers
• Workgroups
• pre-defined groups of member computers

11
The Development of Network Operating Systems
(continued)

• Windows 95
• expanded peer-to-peer networking capabilities
• Windows Me
• better networking capabilities for home use
• Windows NT 3.1
• intended for industrial strength networking from
  the beginning

12
The Development of Network Operating Systems
(continued)

• Windows 2000
• Server and Professional (Workstation)
• Windows 2000/XP/Server 2003
• contain the core elements of Windows 2000 kernel
• home and small office networking

13
Local and Wide Area Networks

• Local area network (LAN)
• one in which the service area is relatively small
  or one spread throughout a floor in a building
• Wide area network (WAN)
• one that offers networking services over a long
  distance, such as between cities, states, or
  countries

14
Network Topologies

• Topology
• physical design of the network
• Bus topology
• designed like a climbing rope with knots tied
  along the way for a foothold
• beginning and end to the rope, and junctures
  along the way for your feet

15
Network Topologies (continued)

• Ring topology
• one in which the data-carrying signal goes from
  station to station around the ring
• no beginning or end point
• Star topology
• one in which there is a hub in the middle, with
  cable segments coming out of the hub in all
  directions

16
Networking Hardware

• Network interface card (NIC)
• used to computers and other devices connected to
  a network
• unique hexadecimal address, called a device or
  physical address
• also called Media Access Control (MAC) address

17
Networking Hardware (continued)

• Firmware
• software logic on the NIC
• communication between the operating system and
  its NIC is controlled by driver software
• Guided media
• twisted-pair cable
• fiber-optic cable
• Unguided media
• air
• space

18
Networking Hardware (continued)

• Twisted-pair cable
• one or more pair of twisted copper
• UTP-unshielded twisted pair
• Coaxial cable
• more expensive than UTP
• original standard but not often used now
• Fiber-optic cable
• glass or plastic transmitting signals with light

19
Networking Hardware (continued)

• Hub
• common device to connect devices to a LAN
• transmits to all segments
• Switches
• intelligent hub
• transmits only to the destination segment

20
Networking Hardware (continued)

• Wireless access point
• connects wireless devices to a wired network
• Bridge
• used to link segments that are close together
• extend segments
• promiscuous mode
• Routers
• used to join networks, either locally or remotely
• look at routing information in packets before
  forwarding those packets to another network

21
Packets, Frames, and Cells

• Each data unit is called a packet or frame
• terms are sometimes used interchangeably, but
  they are not the same
• both consist of data and transmission control
  information contained in a header
• packet contains routing information
• Data is placed after the header information, and
  followed by a footer or trailer that enables
  detection of a transmission error

22
Packets, Frames, and Cells (continued)

• Transmission
• older networks transmit at 4 Mbps (megabits per
  second), 10 Mbps, and 16 Mbps
• newer networks transmit at 100 Mbps to 10 Gbps
  and faster
• Cell
• data unit designed for high-speed communications
• Payload
• portion of a frame, packet, or cell that contains
  the actual data

23
Packets, Frames, and Cells (continued)

• One element of the cell header is path
  information that enables the cell to take the
  route through the network

24
Networking Protocols

• Protocol
• set of formatting guidelines for network
  communications
• coordinate network communications
• network may use several different protocols

25
Networking Protocols (continued)

• Protocols are used for many types of network
  communications
• Coordinating transport of packets and frames
• Encapsulating data and communication control
  information
• Providing communications to accomplish a specific
  function
• Enabling communications over a long-distance
  network
• Enabling remote users to dial into networks

26
Transport Protocols

• Common transport protocols
• Ethernet
• token ring

27
Transport Protocols (continued)

• Ethernet
• one station on the network transmits at a given
  time
• If two or more stations transmit at the same
  time, frames collide
• transmission control method used by Ethernet is
  called Carrier Sense Multiple Access with
  Collision Detection (CSMA/CD)

28
Transport Protocols (continued)

• Ethernet networks are designed in a bus or star
  topology
• Fast Ethernet
• commonplace
• handle either 10 or 100 Mbps communications

29
Transport Protocols (continued)

• Ethernet versions are compatible with popular
  network operating systems such as
• UNIX
• NetWare
• Windows NT, Windows 2000, and Windows Server
  2003
• Windows 98/Me
• Windows XP
• Mac OS

30
Transport Protocols (continued)

• Token ring
• one network station transmits at a time
• transmissions are controlled by the use of a
  specialized frame, called a token
• transmitted around the network until it is
  captured by a station that wants to transmit

31
Transport Protocols (continued)

• Wireless network
• described by it MAC (medium access control)
  protocol
• carrier sense multiple access with collision
  avoidance (CSWMA/CA)

32
Transport Protocols (continued)

• Network Device Interface Specification (NDIS)
• Microsoft designed
• Open Datalink Interface (ODI)
• Novell designed
• NIC cable interface
• match the type of cable used on the network

33
Communications Protocols

• Communications protocols
• protocols that carry data between two stations
• Internet Packet Exchange (IPX) protocol
• developed to enable a NetWare file server to
  communicate with its client workstations
• encapsulates data and transports it within a host
  transport protocol

34
Communications Protocols (continued)

• ARPANET, the long-distance network that set the
  foundation for the Internet
• Transmission Control Protocol (TCP)
• Internet Protocol (IP)

35
Communications Protocols (continued)

• Sequence Packet Exchange (SPX)
• protocol that provides connection-oriented
  communications
• IPX relies upon SPX to provide reliable,
  error-free communication

36
Communications Protocols (continued)

• IPX works with other specialized service and
  NetWare protocols as follows
• Link Support Layer (LSL)
• NetWare Core Protocol (NCP)
• NetWare Link Services Protocol (NLSP)
• Routing Information Protocol (RIP)
• Service Advertising Protocol (SAP)

37
Communications Protocols (continued)

• NetBEUI (NetBIOS Extended User Interface)
• introduced in the early nineties as the main
  protocol for LAN Manager
• Microsoft does not support in Windows XP and
  Windows Server 2003

38
Communications Protocols (continued)

• TCP/IP
• one of the oldest protocols
• UNIX always used TCP/IP
• TCP
• developed for extremely reliable point-to-point
  communications

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Communications Protocols (continued)

• TCP communication functions
• Establishes the communication session between two
  computers
• Ensures that data transmissions are accurate
• Encapsulates, transmits, and receives the payload
  data
• Closes the communication session between two
  computers

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Communications Protocols (continued)

• The IP makes sure that a frame or packet reaches
  the intended destination
• IP functions with TCP
• Handles packet addressing
• Handles packet routing
• Fragments packets
• Provides simple packet error detection

41
Communications Protocols (continued)

• IP addressing
• dotted decimal notation
• Class A through Class E

42
Communications Protocols (continued)

• Unicast
• one copy of each packet is sent
• Multicast
• recipients are placed in a group

43
Communications Protocols (continued)

• Class A networks
• are identified by a value between 1 and 126 in
  the first position of the dotted decimal address
• Class B
• unicast addressing format for medium-sized
  networks composed of up to 65,536 nodes
• identified by the first octet of bits ranging
  from decimal 128 to 191

44
Communications Protocols (continued)

• Class C
• addresses are used for unicast network
  communications on small networks of 256 nodes or
  less
• range of 192 to 223

45
Communications Protocols (continued)

• Class D
• do not reflect the network size, only that the
  communication is a multicast
• the four octets are used to specify a group of
  nodes to receive the multicast
• range from 224.0.0.0 to 239.255.255.255

46
Communications Protocols (continued)

• Class E
• is used for experimentation, and addresses range
  from 240 to 255 in the first octet

47
Communications Protocols (continued)

• Classless Interdomain Routing (CIDR)
• new way of addressing that puts a slash (/) after
  the dotted decimal notation
• provides more IP address options for medium-sized
  networks
• there is shortage of Class B and Class C addresses

48
Communications Protocols (continued)

• Subnet mask
• enables identification of smaller networks within
  the larger setup

49
Communications Protocols (continued)

• Some protocols include the following
• Routing Information Protocol (RIP)
• Simple Mail Transfer Protocol (SMTP)
• File Transfer Protocol (FTP)
• Telnet
• Hypertext Transfer Protocol (HTTP)

50
Communications Protocols (continued)

• Some protocols include the following
• Point-to-Point Protocol (PPP)
• Simple Network Management Protocol (SNMP)
• Internet Control Message Protocol (ICMP)
• Domain Name Service (DNS)
• Dynamic Host Configuration Protocol (DHCP)

51
Communications Protocols (continued)

• AppleTalk
• protocol used between Macintosh computers
• peer-to-peer protocol

52
Communications Protocols (continued)

• Essential services
• remote access to files over a network
• network print services
• access to computers running MS-DOS or Windows
  operating systems

53
Communications Protocols (continued)

• AppleTalk protocols
• AppleTalk Address Resolution Protocol (AARP)
• AppleTalk Data Stream Protocol (ADSP)
• AppleTalk Session Protocol (ASP)
• Datagram Delivery Protocol (DDP)

54
Communications Protocols (continued)

• AppleTalk protocols (continued)
• Name-Binding Protocol (NBP)
• Printer Access Protocol (PAP)
• Routing Table Maintenance Protocol (RTMP)

55
Implementing Communications Protocols in an
Operating System

• Computer operating systems are designed to
  support one or more communications protocols
• Steps involved in setting up communications
  protocol
• install the protocol software that is written for
  that operating system
• bind the protocol with the NIC

56
Implementing Communications Protocols in an
Operating System (continued)

• Mac OS X Network panel
• Configuration of IP address and subnet mask
• Automatic configuration of IP address using DHCP
• Identification of the nearest router by IP
  address
• Identification of Domain Name Service (DNS)
  servers by IP address
• Identification of search domains by IP address

57
Implementing Communications Protocols in an
Operating System (continued)

• Most UNIX systems have TCP/IP networking support
  built in
• UNIX/Linux
• configure a loopback device

58
Implementing Communications Protocols in an
Operating System (continued)

• Red Hat Linux GNOME interface
• configure a network connection by clicking the
  Start icon on the panel, pointing to Programs,
  pointing to System, and clicking Network
  Configuration
• NetWare
• IPX and TCP/IP can be set up in a window that
  appears when NetWare is installed

59
Implementing Communications Protocols in an
Operating System (continued)

• Communications protocols are set up in Windows
  95/98/Me and Windows NT 4.0 through the Network
  icon in the Control Panel

60
Integrating Different Operating Systems on the
Same Network

• Key to implementing multiple operating systems on
  one network
• select a transport protocol and communications
  protocols that are supported in all of the
  operating systems

61
Using Operating Systems for Dial-Up Access

• Remote Access Services (RAS) server
• dialing into a LAN
• network services that can be installed
• Point-to-Point Protocol (PPP)
• Point-to-Point Tunneling Protocol PPTP)
• Serial Line Interface Protocol (SLIP)

62
Using Operating Systems for Dial-Up Access

• Security
• very important topic because of potential threats
  from viruses or hackers

63
Using Operating Systems for Dial-Up Access

• Authentication
• way you identify and validate who you are to the
  server
• Encryption
• encoding of the data between you and the server

64
Summary

• Network is a system of information resources and
  productivity tools
• Invented because they enable users to share
  information and information resources over short
  and long distances
• Networks are designed in standardized topologies
  (bus, star, and ring)

65
Summary (continued)

• Standardized communication means
• frames, packets, and protocols
• Protocols act as a common language for
  communications
• Modern operating systems use TCP/IP and IPX/SPX

66
Summary (continued)

• Bridges, switches, and routers can be employed
  for network security
• LANs are smaller networks
• WANs are long-distance networks
• Dial-up access with communications protocols,
  such as SLIP and PPP
• PPP is most commonly used because it can
  transport a combination of protocols