Introduction to Networking Definitions and Terms Objectives After

Introduction to Networking Definitions and Terms

Objectives After completing these slides you will: • Be able to differentiate between peer-to-peer and server-based networks. • Be able to identify a network topology. • Understand the different types of network cabling. • Be able to explain the differences between various network access methods. • Understand Ethernet issues. • Identify logical layers of the internet. • Be able to explain when a specific network protocol is used. • Understand the difference between a MAC address and an IP address.

Networking Overview • A network is two or more devices capable of communicating and sharing resources between them. • Two types of networks are LAN and WAN: – LAN (Local Area Network) – A group of devices sharing resources in a single area such as a room or a building. – WAN (Wide Area Network) – Two or more LANs communicating, often across large distances. The most famous WAN is the Internet.

Types of Local Area Networks • Two types of LANs are Server-Based and Peer-to-Peer Network: – Server-Based Network – A basic type of LAN wherein users login to a controlling computer, called a server and is more secure. The server contains information about who can connect to the network and to what shared resources. It also provides some of these resources. These networks normally consist of 10 or more computers. – Peer-to-Peer Network – One of two basic types of LANs wherein each computer user acts as a server. Each computer stores password and sharing information for its own resources. Usually has fewer than 10 computers. • NOS (Network Operating System) – Special operating system on a server containing utilities for managing users, resources, and security.

Types of Local Area Networks Server-Based Network – Figure # 1

Types of Local Area Networks Peer-to Peer Network – Figure # 2

Network Topologies • Network Topology – Maps of how the physical or logical paths of network devices connect. The three major topologies are star, ring, and bus. • Star Topology – Most common Ethernet network topology where each device connects to a central hub or switch. • Hub – A device used with the Universal Serial Bus or in a star network topology that allows multiple device connections. • Switch – In star networks, a Layer 2 central controlling device. A switch looks at each data frame as it comes through each port. • Ring Topology – Network that is physically wired like a star network but, logically in a ring; passes control from one device to the next in a continuous fashion using a special data packet called a token. Used in Token Ring networks. • Bus Topology – Network wherein all devices connect to a single cable. If the cable fails, the network is down. • Mesh Topology – Network where all devices connect to each other by cabling to provide link redundancy for maximum fault tolerance. Most likely in WANs.

Network Topologies Hub/Switch Network – Figure # 3

Network Topologies Star Topology Network – Figure # 4

Network Topologies Logical Ring Topology Network – Figure # 5

Network Topologies Bus Topology Network – Figure # 6

Network Topologies Network – Table # 1

Network Cabling Cable is normally used as a medium for transporting network data. The most common types are twisted-pair and fiber-optic, although coax is still used in some old networks. • Twisted-Pair Cable – Network cable of eight copper wires twisted into four pairs to prevent crosstalk. – UTP (Unshielded Twisted-Pair) – Most common network cable that comes in different categories for different uses. Categories 3 (voice-grade), 4, and 5 (data). It is unshielded and more susceptible to interference. – STP (Shielded Twisted-Pair) – Same as UTP cable, but with extra foil to prevent outside noise from interfering with data on the cable. • Crosstalk – Where signals from one wire interfere with the signal on an adjacent wire. • Plenum cable is treated with Teflon or fire retardant materials to reduce the risk of fire. It produces less smoke and is less toxic when burning.

Network Cabling • Fiber-Optic Cable – An expensive network cabling made of plastic or glass fibers that carry data in the form of light pulses. Most often used to connect network devices such as switches together into a network backbone or for connecting networks together in a WAN. More secure and not affected by crosstalk or other interference like copper cable. – Single-Mode – A type of fiber-optic cabling that sends one light beam down the cable. Used for longer distance applications. – Multi-Mode – A type of fiber-optic cabling that allows multiple light signals to be sent along the same cable. Used for shorter distances. • Coaxial Cable – Type of copper network cabling used in older Ethernet networks as well as mainframe and minicomputer connections. Has a single, center wire conductor with an outer braided shield.

Network Cabling UTP Cable Network – Figure # 7

Network Cabling Fiber-Optic Cable Network – Figure # 11

Network Cabling Coax Cable with Connector Network – Figure # 12

Access Methods There are standard rules by which computers on a network must adhere to in order to communicate. These rules are known as a common access method. • CSMA/CD (Carrier Sense Multiple Access/Collision Detect) – A common access method used by Ethernet. • Token Passing – The common access method used by fiber and Token Ring networks. • CSMA/CA (Carrier Sense Multiple Access/Collision Avoidance) – A common access method used in wireless and Apple networks. • Token – Small data packet passed from one networked device to another in a ring topology.

Ethernet Issues and Concepts • Two types of transmissions used in Ethernet networks: • Half Duplex – A serial device setting that allows either the sending or the receiving device to send data, one device at a time. Data can travel both ways on a cable, but not at the same time. • Full Duplex – A serial device setting that allows the sending and receiving device to send data simultaneously. Data can travel both ways on a cable at the same time.

Layers of the Internet • One logical view of the Internet has five layers – Physical Layer – Layer 1 this model defines how bits are sent and received across the network between two pieces of hardware. – Data Link Layer – in layer 2 bits are transferred across the network by encapsulating (grouping) them into frames. – Network Layer – in layer 3 the segments are sent between the sender and receiver. – Transport Layer – in layer 4 breaks a message into segments and passes to the Network Layer. – Application Layer – in layer 5 we have network related applications like telnet, ftp, etc.

Layers of the Internet • In the Physical layer actual bits are sent either as electrical signals on wires, or electromagnetic radiation through fiber-optic cables or transmitted. • In the Data Link layer the information being transmitted is a frame that has the actual info (datagram), header and trailer. The frame headers use MAC addresses to identify source and destination. • The Data Link layer is implemented in the network adapter (NIC) and is a combination of hardware, software, and firmware. • MAC (Media Access Control) is a 48 -bit address burned in NIC ROM.

Networking Protocols • Network Protocol – Specifications that define the network data communication procedures to follow when sending and receiving data. – TCP/IP (Transport Control Protocol / Internet Protocol) – the most common network protocol used by most companies and home users as a standard protocol. Used to access the Internet. – IPX/SPX (Internetwork Packet Exchange/Sequenced Packet Exchange) – original protocol used for connecting to Novell networks. Now TCP/IP is the standard protocol used. – Net. BEUI (Net. BIOS Enhanced User Interface) – is a non-routable protocol used in simple networks; commonly found on peer-to-peer networks.

Network Addressing Network devices have to be able to identify each other in order to communicate across a network. They do this through various network addressing schemes. • MAC Address – One of two types of addresses assigned to network adapters, used when two devices on same network communicate. • IP Address – A type of network adapter address used when multiple networks are linked. It is a 32 -bit binary number with groups of eight bits separated by a dot. • Network Number – Portion of an IP address that represents which network the computer is on.

Network Addressing • Host Number – Portion of an IP address that represents the specific network device. • Broadcast Address – IP address used to communicate with all devices on a particular network. • Subnet Mask – A number the computer uses to determine which part of an IP address represents the network and which portion represents the host.

Network Addressing IP Addressing (Network Number and Host Number) Network – Figure # 15

Network Addressing IP Addressing (Two Network Example) Network – Figure # 16

Network Addressing IP Address Information Network – Table #5

Configuring Networking Some key terms to understand when configuring computers for networking are: • UNC (Universal Naming Convention) – A standard way of naming computers and shared resources on a network. Used at the command prompt to obtain network shares. • DHCP (Dynamic Host Configuration Protocol) – A method to automatically assign IP addresses to network devices from a pool of IP addresses. A computer requests an address from another device running DHCP, usually a server, receives it, and joins the network. • APIPA (Automatic Private IP Addressing) – Assigns an IP address and mask to the computer when a DHCP server is not available. • Default Gateway – The IP address of the Layer 3 device, such as a router, that is directly connected to its immediate network and acts as a doorway or director to other remote networks.

Configuring Networking • DNS (Domain Name System) Server – Application on a network server that translates Internet names (also known as Fully Qualified Domain Names or hostnames) into IP addresses. • URL (Universal Resource Locator) – A method of accessing Internet resources by using a simple, easily remembered name assigned to an IP address. An example of a URL is: www. scottjonespub. com, which is much easier to remember than the IP address : 167. 160. 239. 173. • WINS (Windows Internet Naming Service) Server – Keeps track of IP addresses assigned to a specific computer name. A user can type in a computer name to connect and the server will translate it to the computer’s IP address.

Configuring Networking Default Gateway Network – Figure #17

Network Troubleshooting IPCONFIG – A command used with Windows 98, NT, and 2000 to see and modify the current IP settings. • NSLOOKUP – An NT Server and 2000 Server troubleshooting tool that displays network domain names and their associated IP addresses. • Tracert – A network troubleshooting command that displays the path a data packet takes through a network, thus allowing one to see where a fault occurs in larger networks.

Network Troubleshooting Sample Network Configuration Network – Figure #18

Network Troubleshooting WINIPCFG Network – Figure #19

Network Troubleshooting IPCONFIG Network – Figure #20

Dial-up Networking There are several ways in which computers can connect to remote networks: • DUN (Dial-Up Networking) – A remote computer that dials into the Internet or a corporation using a modem. • VPN (Virtual Private Networking) – A remote computer connecting to a remote network by “tunneling” over an intermediate network, such as the Internet or a LAN. • PPP (Point-to-Point Protocol) – A connection-oriented Layer 2 protocol that encapsulates data for transmission over remote networks. Very common for home users dialing in to the Internet.

Dial-up Networking Dial-Up Networking and VPN Network – Figure #21

Dial-up Networking Network Connections Network - Table #7

Internet Software Once a connection is established to a remote network there are several program types that are useful for accessing data. • Browser – A program that views web pages across the Internet. The two most common are Internet Explorer and Netscape Navigator. • Proxy Server – Acts as an agent between an application and a real server for security purposes. • SMTP (Simple Mail Transport Protocol) – is a protocol used for sending and receiving email. Settings for configuring email can be obtained from the network administrator or the ISP being used to connect to the Internet.

Internet Security • There are three major points to remember: – Keep service patches updated on a regular basis. – The latest anti-virus software should be installed and constantly updated. – If the computer connects to the internet, it should be connected behind a firewall. • Cookie – A special program written to collect information and store it on the hard drive. This will contain your preferences when you visit a website. • Firewall – Software or hardware that protects one or more computers from outside attacks.

Network Terminology • Networking Terms and Acronyms To be Familiar With: – Backbone Bandwidth Baseband – Broadband E-mail Fast Ethernet – FDDI Frame FTP – HTML HTTP Infrared – Packet POP SNMP – TCP Telnet UDP

Wireless Networks Overview • Wireless Networks – Transmit data over air using either infrared or radio frequencies. Wireless networks operate at layers 1 and 2 of the OSI model.

Wireless Networks Types • There are two main types of wireless networks: – Ad hoc – also known as peer-to-peer or IBSS (Independent Basic Service Set) – An ad hoc wireless network is when at least two devices such as two computers have wireless NICs. – Infrastructure – Wireless network that connects multiple wireless network devices through an Access Point. • Access Point – is similar to a network hub and connects wireless network devices. • There are three major types of wireless NICs: PC Card, USB, and PCI.

Wireless Networks Types • BSS (Basic Service Set) – Configuration when multiple devices connect to an Access Point. • ESS (Extended Service Set) – The network design when multiple Access Points connect to the same main network. • SSID (Service Set Identifier) - A set of 32 alpha numeric characters used to differentiate between wireless networks. • The channel ID (frequency) between the Access Point and the adapter must match for communication to occur.

Wireless Networks Types 802. 11 b Frequency Channels Network – Table #12

Wireless Network Security Overview • Wireless networks by their nature are insecure. • All transmissions over air occur in clear text making them easy to compromise.

Authentication and WEP • Authentication is the process of determining that a network device or person has permission to enter the wireless network through the access point. • Open Authentication – Allows a wireless network device to send a frame to the access point with the sender’s identity (MAC address). It is used when no authentication is required. • Shared Key Authentication – Requires the use of a shared key to communicate. • WEP (Wireless Equivalent Privacy) – Encrypts data when shared key authentication is used. • Encryption – the process of converting data into an unreadable format.

Default Settings • All wireless networks have default passwords and SSIDs. They should be changed immediately to prevent hackers from gaining access. • SSID Broadcasting – The access point periodically sends out a beacon frame that includes the SSID. Default Access Point Passwords