CCNA Network Fundamentals

Elements of communication– Source (encoding data before transmission)– Transmission Media (Channel)– Information sent– Rules to control transmitting and receiving – Destination (decoding data after receiving)

Chapter Two : Communicating over the Network

Network Structure

Data is sent across a network in small “chunks” called segments

One channel for different uses (multiplexing)

Network Structure

The components of a network– hardware

– software

Network Structure End Devices and their Role in the Network

–End devices form interface with human network & communications network

–Role of end devices: (like IP Phone, PC, Printer…)

• client

• server

• both client and server

Network Structure Devices In Between (Routers, Switches)

– Provides connectivity between end devices

– Manages data flow

– Retransmit data

Network Structure

Network media (types, criteria for choosing)This is the channel over which a message travels

Coaxial Cable

UTP (Unshielded Twisted Pair)

Twisting provide : 1- protection against crosstalk, noise generated by adjacent pairs & 2- cancellation of the magnetic field.

Based on connection layout, 3 types of UTP are existed:

Straight UTP Cable

Side1 : WO O WG B WB G WBr Br

Side2 : WO O WG B WB G WBr Br

Cross-Over UTP CableSide1 : WO O WG B WB G WBr BrSide2 : WG G WO B WB O WBr Br

Roll-Over UTP CableSide1 : WO O WG B WB G WBr BrSide2 : Br WBr G WB B WG O WO

Straight UTP Cable

Cross-Over UTP Cable

Roll-Over UTP Cable

or

Console UTP Cable

Roll-Over Cable consists of RJ-45 on one end & DB-9 on the other end. Conversion adapter from RJ-45 to DB-9 can be used with RJ-45 / RJ-45 Roll-over cable.

Straight UTP Cable : Communicate between dissimilar devices (PC+Hub, PC+Switch, Switch+Router,)

Cross–Over UTP Cable : Communicate between similar devices (PC+PC, Hub+Switch, Router+Router, PC+Router)

Using of UTP Cables

Fiber Cable

Factors for choosing Network Media

Resistance to Electromagnetic Interference (EMI)

Attenuation

Cost

Installation

Security

Which cable has the highest attenuation? Coax, UTP, Fiber

Network Types

Local Area Networks (LANs)- A network serving a home, building or campus is considered a Local Area Network (LAN) : Single Organization

Network Types

Wide Area Networks (WANs)- LANs separated by geographic distance are connected by a network known as a Wide Area Network (WAN)

Network Types

The internet is defined as a global mesh of interconnected networks

Network Types Network representations

Function of Protocol in Network Communication

Network protocols are usedto allow devices to

communicate

successfully

Function of Protocol in Network Communication

Different protocols and how they interact

Protocols are hardware independent

Using Layers to describe net communication

The net communication is a very complex process, if we looked at it as a whole. A simple way to understand this process is to break down the total net communication system into a series of layers. Each layer is responsible for a specific part of net comm.

ISO (International Organization for Standardization)

OSI/RM (Open System Interconnection) → 1984

It provided venders with a set of standards that insured greater compatibility between Net Tech. It has 7 numbered layers

L1 : Physical, L2 : Data Link, L3 : Network, L4 : Transport, L5 : Session, L6 : Presentation, L7 : Application

Layers with TCP/IP and OSI Model

Define OSI

Memorize name & no of layers

Advantages of Layering

• Simple to develop

• Simple to maintain

• Simple to learn (understand)

Layers 7, 6, 5 deal with application

Layers 4, 3, 2, 1 deal with data transport

TCP/IP (Transmission Control Protocol / IP Protocol) This model is a suite of more than 10 protocols, distributed on 4 layers : Application, Transport, Internet & Network Access

Layers with TCP/IP and OSI Model

Compare OSI and TCP/IP model

Theoretical Model Implemented Model

Name , number & briefly explain the layers of OSI model ?

1. Physical Layer : Binary Transmitting.

2. Data Link Layer : Physical Addressing.

3. Network Layer : IP Addressing.

4. Transport Layer : Reliable Communication.

5. Session Layer : Application Programs Communication.

6. Presentation Layer : Data Representation.

7. Application Layer : Application Programs Assisting.

Layers with TCP/IP and OSI Model

Encapsulation :– Identify data pieces of the sent msg– Ensure data pieces are transmitted to the destination– Enable reassembling data pieces

EncapsulationApplication, Presentation, Session → DataTransport → SegmentsNetwork → PacketsData Link → FramesPhysical → Bits (Encoding)

Addressing and Naming Schemes

Labels in encapsulation headers are used to manage communication in data networks

MAC in layer 2 ; Physical Add ; Device Add

IP in layer 3 ; Logical Add

Port No. in layer 4 : identify service (application)

PC Identifiers (Computer Name, Host Name, IP Add, MAC Add)

Computer Name : 256 characters (unique inside only , non standard)

Host Name : 256 characters (always unique , standard)

IP Address : 4 bytes (always unique , standard)

MAC Address : 6 bytes (always unique , standard)

Which company supports computer name in communication?