Chapter 8 - Network Connectivity

Network Connectivity

Guide to Operating Systems Third Edition

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


• 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

Networking Basics


• Hardware

– computers, printers, communications cable

– internetworking devices such as bridges, switches, routers, and hubs

• Software

– client and server network operating systems

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



• 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



• 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




• 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


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



(continued)

• Windows 3.11

– Windows for Workgroups (WFW)

– connects to NetWare, Microsoft, and other servers

• Workgroups

– pre-defined groups of member computers



(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



(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


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


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


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


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


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



• 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



• Hub

– common device to connect devices to a LAN

– transmits to all segments

• Switches

– intelligent hub

– transmits only to the destination segment



• 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


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


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


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


Networking Protocols

• Protocol

– set of formatting guidelines for network communications

– coordinate network communications

– network may use several different protocols


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


Transport Protocols

• Common transport protocols

– Ethernet

– token ring


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)



• Ethernet networks are designed in a bus or star topology

• Fast Ethernet

– commonplace

– handle either 10 or 100 Mbps communications



• 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



• 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



• Wireless network

– described by it MAC (medium access control) protocol

– carrier sense multiple access with collision avoidance (CSWMA/CA)



• 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


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


Communications Protocols (continued)

• ARPANET, the long-distance network that set the foundation for the Internet

– Transmission Control Protocol (TCP)

– Internet Protocol (IP)



• Sequence Packet Exchange (SPX)

– protocol that provides connection-oriented communications

– IPX relies upon SPX to provide reliable, error-free communication



• 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)



• 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



• TCP/IP – one of the oldest protocols

– UNIX always used TCP/IP

• TCP – developed for extremely reliable point-to-point

communications



• 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



• 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



• IP addressing

– dotted decimal notation

– Class A through Class E



• Unicast – one copy of each packet is sent

• Multicast– recipients are placed in a group



• 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



• Class C

– addresses are used for unicast network communications on small networks of 256 nodes or less

– range of 192 to 223



• 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



• Class E

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



• 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



• Subnet mask

– enables identification of smaller networks within the larger setup



• Some protocols include the following:– Routing Information Protocol (RIP)

– Simple Mail Transfer Protocol (SMTP)

– File Transfer Protocol (FTP)

– Telnet

– Hypertext Transfer Protocol (HTTP)



• 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)



• AppleTalk

– protocol used between Macintosh computers

– peer-to-peer protocol



• Essential services

– remote access to files over a network

– network print services

– access to computers running MS-DOS or Windows operating systems



• AppleTalk protocols:

– AppleTalk Address Resolution Protocol (AARP)

– AppleTalk Data Stream Protocol (ADSP)

– AppleTalk Session Protocol (ASP)

– Datagram Delivery Protocol (DDP)



• AppleTalk protocols (continued):

– Name-Binding Protocol (NBP)

– Printer Access Protocol (PAP)

– Routing Table Maintenance Protocol (RTMP)


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



(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



(continued)• Most UNIX systems have TCP/IP networking

support built in

• UNIX/Linux

– configure a loopback device



(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



(continued)

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


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


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)



• Security

– very important topic because of potential threats from viruses or hackers



• Authentication

– way you identify and validate who you are to the server

• Encryption

– encoding of the data between you and the server


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)


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


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

Documents

Chapter 8 - Network Connectivity