Chapter1ccna(Internetwork Basic)

8/3/2019 Chapter1ccna(Internetwork Basic)

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CCNA 640-802Chapter 1: Internetworking


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Chapter 1 Objectives

The CCNA Topics Covered in this chapterinclude:

Internetworking Basics

Layered Models

The OSI Model

Ethernet Networking

Data Encapsulation

Ciscos Three-Layer Model

Chapter 1 Written Labs and ReviewQuestions

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3

How would you say the PC named Bob communicateswith the PC named Sally?


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Switches can replace the hub, breaking up collision domains.


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Heres a list of some of the things that commonly causeLAN traffic congestion:

Too many hosts in a broadcast domain

Broadcast storms

Multicasting

Low bandwidth

Adding hubs for connectivity to the network


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Routers create an internetwork.


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There are two advantages of using routers in your

network:

They dont forward broadcasts by default.

They can filter the network based on layer 3(Network layer) information (e.g., IP address).

Four router functions in your network can be listedas follows:

Packet switching

Packet Routing

Path selection

Packet filtering


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Internetworking devices


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Layered Models

The Layered Approach

A reference model is a conceptual blueprint of how

communications should take place. It addresses all the processes required for effective

communication and divides these processes intological groupings called layers.

When a communication system is designed in this

manner, its known as layered architecture.

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The OSI Model(Open Systems Interconnection Reference Model)

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The OSI Model

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The upper layers


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The OSI Model

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The lower layers


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The OSI Model

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The Layer Functions


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The OSI Model

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Peer to peer comunication


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The OSI Model

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Connection-Oriented Communication


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The OSI Model

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Windowing


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The OSI Model

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Network LayerRouting Table used in a router


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The OSI Model

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Router in an internetwork

Routers use the logical address in a Network layerheader to determine the next hop

Routers can use access lists, created by an

administrator, to control security Layer 3 devices (routers in this case) provide

connections between virtual LANs (VLANs).

Routers can provide quality of service (QoS) forspecific types of network traffic.


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The OSI Model

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Data Link Layer


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The OSI Model

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Logical Link Control LLC

Provides an interface between the MAC layer and upper-layer

Maintaining orderly delivery of frames through

sequencingControlling the flow or rate using:

AcknowledgmentBufferingWindowing

Removing framing information and foward to the Network


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The OSI Model

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Media Acess Control MAC

Defines specifications for controlling access to the media

Add Cyclical Redundancy Check(CRC) for error

checking Convert frames into bits to send across the network Identifying the network devices and networktopologies Defining an address(MAC) for each physical device

on the network Controlling access to the transmission medium


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Binary Addressing

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Binary to Decimal Memorization Chart10000000 12811000000 19211100000 22411110000 24011111000 24811111100 25211111110 25411111111 255

BINARY 128 64 32 16 8 4 2 1 DECIMAL

10000100 1 0 0 0 0 1 0 0 132

11010010 1 1 0 1 0 0 1 0 210

10111000 1 0 1 1 1 0 0 0 184

10100110 1 0 1 0 0 1 1 0 166

Conversion Example


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The OSI Model

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A hub in an network


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The OSI Model

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A Switch in an network


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Ethernet Networking

Ethernet is a contention media access method thatallows all hosts on a network to share thesamebandwidth of a link.

Ethernet is popular because its readily scalable,

meaning that its comparatively easy to integrate

new technologies, such as Fast Ethernet andGigabit Ethernet, into an existing networkinfrastructure.

Its also relatively simple to implement in the first

place, and with it, troubleshooting is reasonablystraightforward.

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Ethernet Collision Detection

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CSMA/CD


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Half and Full Duplex

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Half-duplex Ethernet is defined in the original 802.3Ethernet; Cisco says it uses only one wire pair with adigital signal running in both directions on the wire.

But full-duplex Ethernet uses two pairs of wires instead of

one wire pair like half duplex. And full duplex uses apoint-to-point connection between the transmitter of thetransmitting device and the receiver of the receivingdevice.

Full-duplex Ethernet can be used in three situations: With a connection from a switch to a host With a connection from a switch to a switch With a connection from a host to a host using acrossover cable


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Ethernet Addressing

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The MAC, or hardware, address is a 48-bit (6-byte) addresswritten in a hexadecimal format.


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Ethernet at the Physical Layer

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The IEEE 802.3 and original Ethernet Physical layerspecifications.


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Ethernet Cabling

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Ethernet cabling is an important discussion, especially if youare planning on taking the Cisco exams.

Three types of Ethernet cables are available:

Straight-through cable

Crossover cable Rolled cable


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Ethernet CablingUTP

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Straight Through

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The straight-through cable is used to connect Host to switch or hub Router to switch or hub


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Crossover Cable

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The crossover cable can be used to connect Switch to switch Hub to hub Host to host Hub to switch Router direct to host


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Rolled Cable

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Although rolled cable isnt used to connect any Ethernet

connections together, you can use arolled Ethernet cable toconnect a host to a router console serial communication (com)

port.


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Using Hyper Terminal

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Notice the settings for Hyper Terminal


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What type of cable is used?

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What type of cable is used foreach connection?

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Data Encapsulation

When a host transmits data across anetwork to another device, the data

goes through encapsulation:

It is wrapped with protocolinformation at each layer of the OSImodel.

Each layer communicates only withits peer layer on the receivingdevice.

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The OSI Model

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Data encapsulation


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The OSI Model

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Data De-encapsulation


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PDU

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Port Numbers

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The Transport layer uses port numbers to define both the virtual

circuit and the upper-layer process.


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Ciscos Three-Layer Model

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The following are the three layers and their typical functions: The core layer: backbone

The distribution layer: routing The access layer: switching


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Review Question

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Hub Hub

How many broadcast domains areshown?


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Review Question

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Hub HubHub HubHub Hub

Switch Switch

How many collision domains

are shown?


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Which of the hosts can transmitsimultaneously without causing

collisions?HubSwitch

How many collision and broadcast

domains are show?

A FEDB C


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How many collision domain, broadcastdomain.


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Written Labs and ReviewQuestions

Open your books and go through all thewritten labs and the review questions.

Review the answers in class.

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Chapter1ccna(Internetwork Basic)