An Introduction

to Networking

Let us get acquainted!1. What is your name and how would you

like us to address you?2. What is your background in networking

(classes, experience)?3. Why did you sign up for this class and

what are your expectations?4. Would you be interested in the CCNA,

CCNP, MCSE, MCSA track?5. What is your next step in technical

training and industry certification after finishing this class?

Networks and Standalone Computers

Network– Group of computers and other devices

connected by some type of transmission media– Networks enable users to share devices and

data, collectively called a network’s resources Standalone computer

– Uses programs and data only from its local disks and is not connected to a network

Sneakernet

Method of sharing data by copying it to a disk and carrying the disk from computer to computer

Local and Remote Computers

Local computer– Computer on which user is working

Remote computer– Computer that user controls or works on via

network connection

Peer-to-Peer Network

Computers communicate on single segment of cable and share each other’s data and devices

Simple example of a local area network (LAN)

Local Area Network (LAN)

Network of computers and other devices confined to relatively small space

LANs involving many computers are usually server-based– On a server-based network, special

computers (known as servers) process data for and facilitate communication between other computers on the network (known as clients)

Networking Basics Workstation

– Computer that typically runs a desktop operating system and connects to a network

Client/server architecture– Networking model in which clients use central

server to share applications, devices, and data

Networking Basics

Client/server network– Network based on client/server architecture

Network operating system– Special software designed to manage data and

other resources on a server for a number of clients

Networking Basics

Advantages of Server-Based over Peer-to-Peer Networks

User login accounts and passwords can be assigned in one place

Access to multiple shared resources can be centrally granted

Servers are optimized to handle heavy processing loads and dedicated to handling requests from clients

Servers can connect more than a handful of computers

MANs and WANs Metropolitan area network (MAN)

– Network connecting clients and servers in multiple buildings within limited geographic area

Wide area network (WAN)– Network that spans large distance and connects

two or more LANs

– The Internet is an example of a very intricate and extensive WAN that spans the globe

WAN

Elements Common to AllServer-Based Networks

Client– In addition to referring to a computer on the

network, may also refers to human user of client workstation

Server Workstation Network interface card (NIC)

– Enables workstation to connect to the network and communicate with other computers

Elements Common to AllServer-Based Networks

Network operating system (NOS) Host

– Server that manages shared resources

Node– Client, server, or other device that can

communicate over a network and that is identified by a unique identifying number, known as its network address

Elements Common to AllServer-Based Networks

Elements Common to AllServer-Based Networks

Protocol– Rules network uses to transfer data

Data Packets– The distinct units of data transmitted from one

computer to another on a network

Elements Common to AllServer-Based Networks

Addressing– Scheme for assigning unique identifying

number to every workstation on network

– The number that uniquely identifies each workstation and device on a network is its address

Elements Common to AllServer-Based Networks

Transmission media– Means

through which data are transmitted and received

How Networks Are Used

Services– Features provided by a network

• File and print services

• Communications services

• Mail services

• Internet services

• Management services

MDF in a Multi-Story Building

MDF in a Multi-Building Campus

Horizontal and Backbone Cabling (Type A)

MDF

IDF

3000m

The Seven Layers of the OSI Model

InternationalOrganization ofStandardization

ISO

Layer7 The application layer is the

OSI layer that is closest to the user; it provides network services to the user’s applications. It differs from the other layers in that it does not provide services to any other OSI layer, but rather, only to applications outside the OSI model. Examples of such applications are spreadsheet programs, word processing programs, and bank terminal programs. If you want to remember Layer 7 in as few words as possible, think of browsers.

Layer 6 The presentation layer

ensures that the information that the application layer of one system sends out is readable by the application layer of another system. If necessary, the presentation layer translates between multiple data formats by using a common format. If you want to think of Layer 6 in as few words as possible, think of a common data format

Layer 5 As its name implies, the

session layer establishes, manages, and terminates sessions between two communicating hosts. The session layer provides its services to the presentation layer. It also synchronizes dialogue between the two hosts' presentation layers and manages their data exchange. If you want to remember Layer 5 in as few words as possible, think of dialogues and conversations.

Layer 4

The transport layer segments data from the sending host's system and reassembles the data into a data stream on the receiving host's system. Layer 4 is the boundary between media-layer protocols and host-layer protocols. Layer 4 also deals with Flow Control (Windowing), and Reliability of Communication (Acknowledgement).

Layer 3

The network layer is a complex layer that provides connectivity and path selection between two host systems that may be located on geographically separated networks. If you want to remember Layer 3 in as few words as possible, think of path selection, routing, and addressing.

Layer 2 The data link layer provides

reliable transit of data across a physical link. In so doing, the data link layer is concerned with physical (as opposed to logical) addressing, network topology, network access, error notification, ordered delivery of frames. If you want to remember Layer 2 in as few words as possible, think of frames and media access control.

Layer 1 The physical layer defines the

electrical, mechanical, procedural, and functional specifications for activating, maintaining, and deactivating the physical link between end systems. Such characteristics as voltage levels, timing of voltage changes, physical data rates, maximum transmission distances, physical connectors, and other, similar, attributes are defined by physical layer specifications. If you want to remember Layer 1 in as few words as possible, think of signals and media.

Encapsulation

Summary of the OSI ModelLayer Description

5 Conversion Steps to Encapsulate Data