1. Guide to Operating Systems, 4th ed.
Chapter 9: Network Connectivity

2. Objectives
Explain networking basics, such as network topologies, networking hardware, packaging data to transport, and how devices connect to a network
Describe network transport and communications protocols, and determine which protocols are used in specific computer operating systems
Explain how to integrate different operating systems on the same network
Guide to Operating Systems, 4th ed. 2

3. Networking Basics
Network – a system of computing devices, computing resources, information resources, and communication devices that are linked together with cables or wirelessly with radio waves or light.
Combined wireless and cabled network
Guide to Operating Systems, 4th ed.

4. Networking Basics
The basic principle of networking is similar to connecting telephones.
In a telecommunications system that uses cell phones, the cell phone connects to a base station through a cell tower within its local area using radio waves.
Each base station is connected to a mobile telephone switching office (MTSO), which connects and coordinates cell phone and land-line communications.
Guide to Operating Systems, 4th ed.

5. Networking Basics
Computer networking that uses wireless communications is similar in that each computer connects to a wireless access point within its area.
The wireless access point is connected to a larger network or the Internet as a way to coordinate communications in the same or different wireless cell or on a cabled network.
Guide to Operating Systems, 4th ed.

6. Networking Basics
Guide to Operating Systems, 4th ed.

7. Networking Basics Networks have hardware and software elements.
Hardware components:
Computers
Printers
Communications cable
Networking devices
Software components
Client and server operating systems
Device drivers
Networking protocols
Rules for network communications
Guide to Operating Systems, 4th ed.

8. Client and Server Operating Systems
Client OS – enables a workstation to run applications, process information locally, and communicate with other computers and devices over a network.
Examples of Client Oss:
WindowsXP/Vista/7, UNIX/Linux, Mac OS X and Snow Leopard
Workstation – a computer that has a CPU and can run applications locally or obtain applications and files from another computer on a network.
Guide to Operating Systems, 4th ed.

9. Client and Server Operating Systems
Server OS – coordinates network activities, authenticates clients to access the network, and enables client workstations to access shared network resources such as printers, files, or software.
Examples of server OSs:
Windows Server 2003/Server 2003 R2, Server 2008/Server R2, UNIX/Linux (can be either client or server), and Mac OS X server Linux
Guide to Operating Systems, 4th ed.

10. Client and Server Operating Systems
Security – another important function of a server OS.
Can be used to test the credentials of clients before clients are allowed to access network resources.
Basic way to do this: user account and passwords
Authentication
Certificate services – digital certificates to verify that a user or entity (a file) is trustworthy.
Important on networks that involve money and secure data transactions.
Statement of Health (SoH) – certifies that the client is secure and is current on OS updates
Available in Windows Server 2008/R2
Guide to Operating Systems, 4th ed.

11. Client and Server Operating Systems
Security – another important function of a server OS.
Remote Installation Services (RIS) – used to install client OSs on a mass scale (Windows Server 2003/R2)
Windows Deployment Services (WDS) – updated version of RIS that became available in Windows Server 2008/R2
When you use RIS or WDS to install a client OS, you create an OS image containing specific settings, and then the image is downloaded and installed on the clients.
Centralizes installation of software and OSs on client workstations.
Saves time and money
Guide to Operating Systems, 4th ed.

12. Client and Server Operating Systems
Publishing an application – Windows Server 2003/Server 2003 R2 and Server 2008/Server 2008 R2 enables Windows XP/Vista/7 clients to install custom configured application software from a central Windows server via the clients’ local Control Panels.
Guide to Operating Systems, 4th ed.

13. Client and Server Operating Systems
Assigning applications – A Windows Server 2003/Server 2003 R2 and Server 2008/Server 2008 R2 feature that enables a client to automatically start a particular version of software through a desktop shortcut or menu selection, or by clicking a file type.
Clicking a document with a .doc or .docx extension.
If user accidentally deletes the shortcut, it is automatically reinstalled the next time the user logs onto the network.
Guide to Operating Systems, 4th ed.

14. Local and Wide Area Networks
Networks are often classified by their reach (scope).
Local area network (LAN) – the service area is relatively small, such as a network in an office area contained on one floor or in one building.
Wide area network (WAN) – offers networking services over a long distance, such as between cities, states or countries
Often connect LANs over a long distance
Example of a simple WAN – using a cable or DSL modem to connect to your ISP, which connects you to other networks worldwide
Guide to Operating Systems, 4th ed.

15. Network Topologies
Topology – the physical design of the network, (physical topology) or the path data takes when it goes from one computer to another (logical topology).
Bus topology – designed as a straight line (central cable) to which all computers and devices attach with two end points that must be terminated to keep the signal from reflecting back along the path
Guide to Operating Systems, 4th ed.

16. Bus Topology
Guide to Operating Systems, 4th ed.

17. Network Topologies
Ring topology – the data-carrying signal goes from station to station around a logical ring like in a circle of computers connected to one another until it reaches the target destination.
There is no beginning or, end point.
No terminators.
No longer used much in LANs – found in some WANs
Guide to Operating Systems, 4th ed.

18. Network Topologies
Star topology – computers or devices (nodes) on the network connect to a central device such as a switch or wireless access point.
In a cabled network, the switch sends the signal onto the segment that has the destination computer for the particular communication that is transmitted.
Every segment is terminated inside the switch at one end and inside the computer at the other end.
Most popular network topology because it has the most flexibility in terms of providing for future growth and adding high-speed networking capability.
Guide to Operating Systems, 4th ed.

19. Network Topologies
Star Topology
Guide to Operating Systems, 4th ed.

20. Network Topologies
Star-bus hybrid topology – combines the logical communications of a bus with the physical layout of a star.
Each segment radiating from the star (central connecting device) is like a separate logical bus segment but with only one or two computers attached.
The segment is still terminated at both ends but the advantage is that there are no exposed terminators as on a regular bus topology.
On each segment, one end is terminated inside the switch and the other is terminated at the device on the network.
You can connect multiple switches, access points, and other network devices to expand the network in many directions.
Guide to Operating Systems, 4th ed.

21. Star-Bus Hybrid Topology
Guide to Operating Systems, 4th ed.

22. Networking Hardware
The hardware that supports networking includes network interface cards, communications media such as cables or wireless media and various devices that control the flow of information through and beyond the network (switches, bridges, and routers).
Guide to Operating Systems, 4th ed.

23. Networking Hardware
Network interface card (NIC) – a card that goes into a computer’s expansion slot, or that is built into a network device or a computer, or that plugs into a USB port.
The NIC is equipped with a connector that enables it to attach to the network communications cable, or an antenna that enables it to communicate via radio waves.
Each NIC has a unique hexadecimal address, assigned by the manufacturer (a device / physical address) which identifies it to the network.
Guide to Operating Systems, 4th ed.

24. Networking Hardware
The physical address is also called the Media Access Control (MAC) address.
Used much like a postal address because it enables communications to be sent to specific destination computers on the same network.
The software logic on a NIC consists of one or more programs (firmware) residing in a programmable chip on the NIC card.
Communication between the OS and the NIC is controlled by driver software written by the manufacturer of the NIC.
Guide to Operating Systems, 4th ed.

25. Networking Hardware
Devices on a network with unique physical (MAC) addresses
Guide to Operating Systems, 4th ed.

26. Networking Hardware
Cables and Wireless Media – A communication medium is anything through which data is transmitted.
Twisted-pair cable – consists of one or more pairs of twisted copper wires bundled together within a plastic outer coating.
Wires are twisted to reduce electromagnetic interference (EMI) or noise.
Comes in two configurations: Unshielded Twisted Pair (UTP) and Shielded Twisted Pair (STP).
STP is faster and more reliable than UTP but it is more expensive and less flexible.
UTP is the most often used on LANs today.
Twisted-pair cable comes in several categories with variations of Cat 5 and Cat 6 as most common.
Reflects the speed and type of communications that can be carried on the cable.
Guide to Operating Systems, 4th ed.

27. Networking Hardware
Coaxial cable (coax) – A copper wire surrounded by several layers: a layer of insulating material, a layer of woven or braided metal, and a plastic outer coating.
More expensive and cumbersome than twisted pair.
Not often used in LANs today.
Not used for WANs.
Mostly used for home Internet connections.
Cable television (CATV) uses coax cable.
Most connections are made using hybrid fiber/coax (HFC) cable that consists of optical fibers (fiber optic) and copper cables (coax) in different combinations.
Guide to Operating Systems, 4th ed.

28. Networking Hardware
Fiber-optic cable – consists of dozens or hundreds of thin strands of glass or plastic that transmit signals using light.
Can carry more signals than wire cables.
Are significantly faster.
Are less prone to electrical interference.
Much more difficult and expensive to install and modify.
Most local and long-distance phone companies have replaced existing phone lines with fiber optic cable.
Businesses use fiber-optic cables on high-traffic network backbones (main connecting links between networks).
Guide to Operating Systems, 4th ed.

29. Networking Hardware
Wireless transmissions are carried by radio frequencies (RF) or light (infrared) including radio waves and microwaves.
Cell phones also use wireless technology but broadcast in a different frequency range than wireless LANs.
Guide to Operating Systems, 4th ed.

30. Networking Hardware
Network Devices – used to connect computers and network-attached devices like printers to each other and to connect networks to each other.
NIC – Each device (node) connected to a network must have a NIC which connects through a cable or wireless antenna to a hub, switch, bridge, router, or wireless access point, which in turn connects to a LAN or WAN.
Hubs – were once used in bus and star LANs to connect computers or devices to a local network but have been superseded by switches.
Guide to Operating Systems, 4th ed.

31. Networking Hardware Network Devices (contid.)
Switch – like a hub but more “intelligent”.
Communications that go through hubs are broadcast to all segments attached to the hub.
A switch only transmits the information to the segment where the destination device resides.
Wireless access point – a device that connects wireless devices to a wired network.
Guide to Operating Systems, 4th ed.

32. Networking Hardware Network Devices (contid.)
Bridge – Used to link network segments that are close together.
Used to extend segments, such as when more stations must be added, but the primary segment already contains the maximum length of cable or number of stations permitted by network standards.
Used to segment a network into smaller networks as a way to control traffic and reduce bottlenecks at busy network intersections.
Can be used to link segments that use different cable types.
Network administrators today use switches instead of bridges.
Switches provide additional logic that enables them to move network traffic more efficiently than the old-style bridges.
Guide to Operating Systems, 4th ed.

33. Networking Hardware Network Devices (cont.)
Router - used to connect networks.
Connect dissimilar networks.
Can be programmed to act as a firewall to filer communications.
Hardware or software that secures data from being accessed outside a network and can prevent data from leaving the network.
Keeps tables of network addresses that identify each computer on the network along with the best “routes” to other network addresses.
Can use routing information in network packets to route individual packets to the proper destination.
Guide to Operating Systems, 4th ed.

34. Packets, Frames, and Cells
Each network device translates data into individual units and then places the units onto the network media for transmission.
Each data unit is called a packet or frame.
Packet – contains routing information that allows the packet to be forwarded to specific networks.
Frame – contains information about the specific sending or receiving device
The actual data is placed after the header information and followed by a footer (trailer) that enables detection of a transmission error.
Basic packet format
Guide to Operating Systems, 4th ed.

35. Packets, Frames, and Cells
Some networks require extra capacity for high-speed transmissions more than 1Gbps (networks that have a high proportion of multimedia applications or on which large files are regularly transmitted).
Cell – data unit designed for high-speed communications.
Has a control header and a fixed-length payload.
Payload – that portion of a frame, packet, or cell that contains the actual data.
One element of the cell header is path information that enables the cell to take the route through the network that is most appropriate for the type of data carried within the cell.
Exact format of a frame, packet, or cell is determined by the type of protocol used on a network.
Guide to Operating Systems, 4th ed.

36. Networking Protocols
Protocol – A set of formatting guidelines for network communications (like a language), so that the information sent by one computer can be accurately decoded by another.
Protocols also coordinate network communications so that data is transported in an orderly fashion, preventing chaos when two or more computers want to transmit at the same time.
A network may use several different protocols, depending on the types of communications and the types of devices that are connected.
Guide to Operating Systems, 4th ed.

37. Networking Protocols Protocols are used for:
Coordinating transport of packets and frames among network devices.
Encapsulating data and communication control information.
Providing communications to accomplish a specific function.
Such as enabling the destination computer to tell the source computer to slow its transmission speed because it is too fast for the destination computer.
Enabling communications over a long-distance network, such as the Internet.
Enabling remote users to dial into networks, access virtual private networks, or access networks through cable and wireless technologies.
Transporting test, network status, and other network management information.
Guide to Operating Systems, 4th ed.

38. Transport Protocols
Two of the most important types of protocols are those that coordinate transport and those that communicate and coordinate how data is encapsulated and addressed.
Ethernet
Wireless
Standards for Ethernet and wireless networking are defined as part of the standards established by the Institute of Electrical and Electronics Engineers (IEEE) through its 802 standards committee
The 802 standards are followed by network administrators and manufacturers to ensure all network devices will be able to communicate with each other.
Guide to Operating Systems, 4th ed.

39. Transport Protocols
Ethernet – only one station should transmit at a given moment.
If two or more devices transmit at the same time, frames collide.
The transmission control method used is called carrier sense multiple access with collision detection (CSMA/CD).
The NICs of computers and devices check the network communications cable for a carrier signal that contains an encoded frame.
If the device’s NIC detects a carrier signal, and if the NIC decodes its own device address within the frame, it forwards that packet to its firmware for further decoding.
If the frame does not contain its device address, then the NIC does not process the signal any further.
Guide to Operating Systems, 4th ed.

40. Transport Protocols Ethernet (cont.)
When the detected carrier signal is twice (or more) the strength of a normal carrier signal, this indicates that at least two network stations transmitted at the same time.
In this situation, a collision occurred, and a transmitting station sends a “jam” signal to warn all other stations.
After the jam signal is sent, every station waits a different amount of time before attempting to transmit again.
Networks that use Ethernet are designed in a bus topology or a star-bus topology.
Ethernet star-bus hybrid networks are the most commonly used networks.
Typical speeds supported today are 100 Mbps (Fast Ethernet) and 1 Gbps (Gigabit Ethernet).
10 and 100 Gbps Ethernet are mostly used on Ethernet backbones.
Guide to Operating Systems, 4th ed.

41. Transport Protocols Ethernet (cont.)
All versions of Ethernet are compatible with popular OSs such as:
UNIX/Linux
Windows XP/Vista/7
Windows Server 2003/Server 2003 R2
Windows Server 2008/Server 2008 R2
Mac OS X Leopard and Snow Leopard
Guide to Operating Systems, 4th ed.

42. Transport Protocols
Wireless Network – Can be described by its MAC (Medium Access Control) protocol.
The most prevalent protocol used in a wireless LAN is carrier sense multiple access with collision avoidance (CSMA/CA) – a variation of CSMA/CD used in Ethernet.
A wireless station that wants to transmit, listens for other transmissions.
If there are transmissions, it will wait a specified amount of time and then listen again.
If there are no transmissions, the station will begin transmitting.
Guide to Operating Systems, 4th ed.

43. Transport Protocols Wireless Network (contid)
Four main IEEE wireless specifications today:
Summary of wireless communications technologies
Guide to Operating Systems, 4th ed.

44. Transport Protocols
A transport protocol is interfaced with an OS through three elements:
Network driver specification built into the OS;
A NIC;
A NIC driver.
Network OS are built to offer special elements (hooks) in the OS kernel (program code), that enable the OS to interface with a network.
Microsoft and 3COM designed the Network Device Interface Specification (NDIS) and Windows-based NDIS drivers for this purpose.
Guide to Operating Systems, 4th ed.

45. Transport Protocols
UNIX and Linux OSs are compatible with the NDIS driver through using open source software, such as NDISwrapper.
Mac OS X is also compatible with NDISwrapper when using a nonproprietary NIC (Intel) in a Mac.
Guide to Operating Systems, 4th ed.

46. Transport Protocols
When you set up an OS to work on an Ethernet or wireless network, the first step is to purchase an Ethernet or wireless NIC for the computer running the OS.
If the NIC is for a wired network, the NIC cable interface must also match the type of cable used on the network.
Choose a wireless NIC if no cable is needed.
After the NIC is installed in an open expansion slot in the computer, the next step is to boot the OS and install the NIC driver software, which links the NIC into the network computing hooks in the kernel.
Guide to Operating Systems, 4th ed.

47. Transport Protocols
After the NIC setup is complete, and the computer is connected to the network, the OS, NIC, and driver handle the work of converting data created at the computer to an Ethernet or wireless format for transport over the network.
The same three elements also enable the computer to receive packets or frames and convert them into data that the computer can interprete.
Guide to Operating Systems, 4th ed.

48. Communications Protocols
The development of communications protocols (the protocols that carry data between two communicating stations, and are encapsulated in Ethernet or wireless transport protocols) is related to the network OSs in which they are used.
Today, all OSs discussed in this book use the TCP/IP family of protocols (protocols developed for the Internet).
In the early 1980’s, researchers implemented and combined two protocols for use on the U.S. Department of Defense Advanced Research Projects Agency Network (ARPANET), the long-distance network that became the foundation of the Internet.
Guide to Operating Systems, 4th ed.

49. Communications Protocols
The protocols developed for ARPANET, Transmission Control Protocol (TCP), and Internet Protocol (IP), or the combination called (TCP/IP), are now used worldwide over the Internet and on most other networks.
Guide to Operating Systems, 4th ed.

50. Communications Protocols
Transmission Control Protocol (TCP)
Developed for extremely reliable point-to-point communications between computers on the same network.
This protocol establishes communication sessions among applications on two communicating computers, making sure there is a mutually agreeable “window” of transmission characteristics.
TCP performs some of the following 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
Guide to Operating Systems, 4th ed.

51. Communications Protocols
Internet Protocol (IP)
Used to make sure that a packet reaches the intended destination.
IP performs the following complementary functions with TCP:
Handles packet addressing
Handles packet routing
Fragments packet, as needed, for transport across different types of networks
Provides simple packet error detection in conjunction with the more thorough error detection provided by TCP
Guide to Operating Systems, 4th ed.

52. Communications Protocols
TCP/IP comes in two version IPv4 and IPv6
IPv4 is the most commonly used version, but has a limitation in that the world is nearly out of new IP addresses.
IPv4 uses a dotted decimal notation that consists of four 8-bit binary numbers separated by periods to produce an IP address used to identify a computer or network device and the network it is on.
The format is: which converts to the decimal value
Part of the address designates a unique identifier for a network called the network identifier (NET_ID).
A school or corporation
Part of the address is the host identifier (HOST_ID).
Distinguishes a computer or network device from any other computer or device on a network.
Guide to Operating Systems, 4th ed.

53. Communications Protocols
There are five IP address classes of IPv4 IP addresses.
The address classes reflect the size of the network, and whether the packet is unicast or multicast.
Unicast – one copy of each packet is sent to each target destination.
If there are eight workstations designated to receive a packet, the packet is transmitted eight times.
Multicast – The recipients are placed in a group. Only one packet is sent to the group, via a router or switch, which then sends the packet to each group member.
Guide to Operating Systems, 4th ed.

54. Communications Protocols
IP address classes
Guide to Operating Systems, 4th ed.

55. Communications Protocols
Class A – assigned to large networks – can have up to 16,777,216 nodes
Class A network address example –
Class B – assigned to medium networks – can have up to 65,536 nodes
Class B network address example –
Class C – assigned to small networks – can have up to 256 nodes
Class C network address example –
Class D – used for multicasts (sent to multiple nodes)
Class E – used for experimentation
Broadcast address: – sent to all nodes on a network
Guide to Operating Systems, 4th ed.

56. Communications Protocols
Classless interdomain routing (CIDR) – newer way of addressing that ignores address class designation.
Puts a slash (/) after the dotted decimal notation.
Example: /14
CIDR provides more IP address options for medium-sized networks.
Subnet mask – used to identify networks or subnetworks (subnet) within a larger network setup
On large networks, subnets allow an administrator to create smaller networks to limit network traffic and congestion on network segments
Guide to Operating Systems, 4th ed.

57. Communications Protocols
Using TCP/IP subnet masks
Guide to Operating Systems, 4th ed.

58. Communications Protocols
Computers and network devices that use IP addressing have two addresses:
MAC address – address burned into the NIC
IP address – assigned by network administrator
The use of two addresses provides better insurance that a packet will reach the right destination, while expending the fewest network resources.
IP addressing makes it possible to send a packet along the best or fastest route for the type of information it contains.
Guide to Operating Systems, 4th ed.

59. Communications Protocols
IPv6 – A newer TCP/IP version that uses 128-bit addresses to solve the shortage of IPv4 addresses.
Provides more specialized networking implementations, such as voice, video, and multimedia applications.
All new OSs support various levels of IPv6.
TCP/IP works with a range of associated protocols that make this a powerful combination for networks of all sizes and types.
Guide to Operating Systems, 4th ed.

60. Communications Protocols
Guide to Operating Systems, 4th ed.

61. Communications Protocols
Three steps involved in setting up a communications protocol in an OS:
Installing the protocol in the OS.
Binding the protocol to the NIC.
Configuring protocol communications parameters.
Installing and Binding a Protocol
Combined into one procedure.
Usually automatic when you install the OS.
TCP/IP is automatically installed unless you specify that it should not be installed.
Binding – Enables the NIC to format data for that protocol and identify the most efficient methods for transporting it.
When two or more protocols are used, binding also enables the NIC to prioritize which protocol to process first.
Guide to Operating Systems, 4th ed.

62. Communications Protocols
Configuring a Protocol – To configure the protocol communication parameters:
Configuring an IPv4 address;
Configuring an IPv6 address;
Which may also require the NET_ID length or IP prefix length.
Specifying the subnet mask (also called the netmask);
Designating a default gateway (the device that links the network to other networks, such as the Internet).
Specifying a preferred DNS server (provides lookup of IP addresses and computer/device names);
Specifying an alternate DNS server (used when preferred DNS server is busy or cannot be reached).
Guide to Operating Systems, 4th ed.

63. Communications Protocols
If a network uses automatically assigned IP addressing through a Dynamic Host Configuration Protocol (DHCP) server, then all you need to do to configure TCP/IP is to specify automatic addressing.
Two advantages:
Not necessary to know any of the TCP/IP configuration parameters, because they are automatically assigned by DHCP.
DHCP Ensures that no two computers are assigned the same IP address.
Guide to Operating Systems, 4th ed.

64. Communications Protocols
Automatic Private IP Addressing (APIPA)
Available in Windows XP/Vista/7, Server 2003/R2, Server 2008/R2.
If automatic addressing is selected but there is no DHCP server on the network, the OS assigns the IPv4 address from a reserved range of –
Guide to Operating Systems, 4th ed.

65. Communications Protocols
Static IP Address:
On some networks there are some computers and devices that must have an IP address that is manually assigned and never changes (servers, switches, routers, etc…)
Important for devices that will be well known and used by other devices for services
Servers are normally given a static IP address.
Guide to Operating Systems, 4th ed.

66. Communications Protocols
Most UNIX/Linux OSs have TCP/IP networking support built in.
Some automatically run a network configuration program when you first boot the computer with an installed NIC.
NIC device drivers are loaded in the kernel.
When the configuration program runs, you must supply information about the network connection, such as the IP address.
If TCP/IP networking is not automatically configured when you first boot, it can be configured later by using the ifconfig command.
A utility typically found in the /etc or /sbin directories, which enables you to assign an IP address, turn on the network interface, and assign a subnet task.
Guide to Operating Systems, 4th ed.

67. Communications Protocols
In Mac OS X Leopard and Snow Leopard, wired and wireless network connections are configured using the Network option from the System Preferences windows.
Guide to Operating Systems, 4th ed.

68. Communications Protocols
Configuring a wireless network connection in Mac OS X Snow Leopard
Guide to Operating Systems, 4th ed.

69. Integrating Different Operating Systems on the Same Network
The key to implementing multiple OSs on one network is to select a transport protocol and communications protocols that are supported in all of the OSs that must be connected.
Ethernet and TCP/IP are supported by most operating systems.
Guide to Operating Systems, 4th ed.

70. Chapter Summary
A network is a system of resources and productivity tools that communicate with each other enabling us to share information over short and long distances
Networks are roughly categorized as LANs or WANs, depending on their areas of service (LANs typically cover a building or floor of a building and WANs are long-distance networks that join LANs and individual users)
Networks are designed in standardized topologies (bus, star, ring, star-bus hybrid) and use standardized communications means, such as frames, packets, and protocols
Protocols are important to network because they act as a common language for communication between devices and provide reliability, delivery of data and monitor networks for problems
Guide to Operating Systems, 4th ed.

71. Chapter Summary
Modern computer operating systems use TCP/IP, which is the communications protocol preference for networks and the Internet
IPv4 is in greatest use today, but networks will eventually convert to IPv6 because it offers a greater range of addresses, better security, and other network improvements
Networking devices such as hubs, bridges, switches, and routers enable network connectivity (hubs and bridges are becoming obsolete) Each device is used to achieve different connectivity goals based on its capabilities
Cabled Ethernet and wireless networks are used separately and also combine to enable flexible networking
Guide to Operating Systems, 4th ed.

72. Chapter Summary
Windows operating systems, UNIX, Linux, and Mac OS X all offer tools for configuring TCP/IP communications, including IP address, subnet mask, gateway, and DNS parameters
Current Windows operating systems, UNIX, Linux, and Mac OS X Leopard and Snow Leopard can be integrated on the same network, in part because they all support TCP/IP as their default communications protocol and are compatible with Ethernet
Guide to Operating Systems, 4th ed.