Local Area Network (LAN)

• Network of users that share computer resources in a limited area
• Local area networks are defined in terms of the protocol and the topology used for accessing the network.
• Protocol - Set of rules established for users to exchange information

The various LAN topologies

Topology - Architecture of a network

Token Ring Topology - A network topology configured in a logical ring that complements the token passing protocol

• Token Passing - A technique in which an electrical token circulates around a network, and control of the token enables the user to gain access to the network

• IEEE - Institute of Electrical and Electronics Engineers, one of the major standards-setting bodies for technological development

• Deterministic - A type of network in which access to the network is provided at fixed time intervals

• Token Ring Hub - A hub that manages the passing of the token in a Token Ring network

Bus Topology - A system in which the computers share the media (coaxial cable) for data transmission

Star Topology - The most common networking topology in today’s LANs, where all networking devices connect to a central switch or hub

Hub Topology - Device that broadcasts the data it receives to all devices connected to its ports

• Multiport Repeater - Another name for a hub

• Broadcast - Transmission of data by a hub to all devices connected to its ports

Mesh Topology - A topology in which all networking devices are directly connected to each other

The concept of CSMA/CD in the Ethernet protocol

• Carrier sense multiple access with collision detection, the Ethernet LAN media access method

The structure of the Ethernet frame

• Frame - A format that provides grouping of information for transmission

The purpose of a network interface card

• Network Interface Card (NIC) - The electronic hardware used to interface a computer to a network

The purpose of a MAC address

• The MAC address provides the physical address for a network interface card but provides no information about its network location or even on what LAN or in which building, city, or country the network resides

How to determine the MAC address for a computer

• Can be obtained from computers operating under Microsoft Windows by typing the ipconfig /all command while in the command mode

The purpose and structure of an IP address

• A unique 32-bit address that identifies on which network a computer is located and differentiates the computer from all other devices on the same network

• identifies on which network a computer is located and differentiates the computer from all other devices on that network. The address is divided into four 8-bit parts.

The concept of private IP addresses

• Private addresses are IP addresses set aside for use in private intranets.

• Intranet - An internal network that provides file and resource sharing but is not accessed from the Internet

The OSI (Open Systems Interconnection) model

7. Application

Function: Support for applications

Example: HTTP, FTP, SMTP (email)

6. Presentation

Function: Protocol conversion, data translation

Example: ASCII, JPEG

5. Session

Function: Establishes, manages, and terminates sessions

Example: NFS, SQL

4. Transport

Function: Ensures error-free packets

Example: TCP, UDP

3. Network

Function: Provides routing decisions

Example: IP, IPX

2. Data link

Function: Provides for the flow of data

Example: MAC addresses

1. Physical

Function: Signals and media

Example: 1. NICs, twisted-pair cable, fiber

The network topologies and technologies used to implement twisted-pair computer networks

• The star topology

How to configure and verify a computer’s IP address

• Network Number - The portion of an IP address that defines which network an IP packet is originating from or being delivered to

• Host Number - The portion of an IP address that defines the location of a networking device connected to the network; also called the host address

The purpose of the link light

• The presence of a link light indicates that the transmit and receive pairs are properly aligned and the connected devices are communicating.

The purpose of using ping to test a network connection

• You can use the ping command, which is available in the Windows command window, to verify that the networking devices are communicating.