CCNA CHAPTER 1 BY jetarvind kumar madhukar

Release 16/07/2009 Jetking Infotrain Ltd.

Internetworking Overview

Chapter 1


Chapter Objectives

Explain line configuration Explain different types of topologies Explain the types of networks Discuss the modes of transmission Discuss the hierarchical network model Discuss the OSI Layers


Point-to-Point Configuration

A dedicated link exists between the two devices


Multipoint Configuration

More than two devices share the same link.


Physical Topology

Represents the physical layout of devices on a network

It is the arrangement of the devices on the network and the way they communicate with each other

Bus

Star

RingTree

MeshPhysical Topology


Local Area Network (LAN)

This is used in a small area, an office or organization The computers can be connected to

each other and other devices, printer or a modem

The rate at which the data is transmitted is very fast


Metropolitan Area Network (MAN) This is used in a large geographical area, town or city Enables high speed connections using fiber optic


Wide Area Network (WAN) This is used in a larger area than MAN, countries or

cities Enables high speed connections using

public networks, telephone lines, satellites, or leased lines


Simplex Mode of Transmission

Only one device can transmit the data, whereas the other can only receive the data


Half Duplex Transmission Mode Both devices can transmit and receive the data, but

not simultaneously

Waki-toky


Full Duplex Mode of Transmission Both the devices can send and receive the data

simultaneously


OSI Model


Application Layer - I

The topmost layer of the OSI model Link between the user and the presentation layer


Application Layer - II

Functions include Authentication File access, transfer and management Directory Services


Presentation Layer Acts as a link between application and the session

layer Defines the forms of text, graphics, video or audio

information that is to be sent to the user


Session Layer Responsible to validate and establish a connection between the

users Each session is divided into sub sessions Functions include

Session Management Synchronization Dialog Control Closing the session


Transport Layer Responsible for source-to-destination delivery of the entire

message divides each message into segments and assigns a sequence

number to each segment Functions include

Service point addressing End-to-end message delivery Segmentation and reassembly Connection control


Flow Control using Three-Way Handshake Three-Way handshake

helps to establish the connection between the two devices


Sliding Window This concept of deciding the window size without

sending an acknowledgement is termed as Windowing


Window Resizing


Network Layer Responsible for routing and logical addressing Assigns IP addresses and routes the packets to the destination Functions include

Source-to-destination delivery Logical addressing Routing Address transformation Multiplexing


Data Link Layer Second layer of the OSI model Functions include

Identifying the encapsulated data Framing Arbitration Physical addressing Error detection


Physical Layer

Responsible for transmitting a bit over the physical medium Converts the data from the data link layer in a format that

the communication medium can carry Functions include:

Line configuration Data transmission Topology Signals


Full and Half Duplex Ethernet

Half Duplex Full Duplex

One wire is used to connect the networks and transmit the data

Two wires are used to connect the networks and transmit the data

Chances of collision if client and server transmit data simultaneously

There are no chances of collision

It uses Carrier Sense Multiple Access with Collision Detection (CSMA/CD) protocol

CSMA/CD not required hence the data transmission rate is 100 percent


Ethernet Frames

Frames are used to transfer the packets They perform the data security check and ensure

that the data is not corrupted


Hierarchical Communications The benefits of Cisco hierarchical model include

High performance Efficient management and troubleshooting Policy creation Scalability Behavior prediction


Core Layer Responsible for fast and reliable transportation of data

across a network Devices include

Cisco Switches in the 7000, 7200, 7500 and 12000 series for connecting to the WAN devices

Catalyst Switches in the 6000, 5000 and 4000 series for connecting to the LAN devices


Distribution Layer

Responsible for routing and managing network traffic Functions include

Packet filtering Access layer aggregation point Control broadcast and multicast Application gateways


Access Layer Layer ensures that the packets are delivered to the

destination computers Functions include

Address filtering Separate collisions domain Share bandwidth Handle switch bandwidth


Ethernet Physical Layer Specification


Straight Through CableOr Patch Cable

Communicated to different

device to each other like as computer to

switch ,hub to switch or router to

computer etc.


Cross-Over Cable

Communicated to same device to each other.

Such as computer to

computer and router to router, switch to switch

etc.


Twisted Pair Cables

Unshielded Twisted Pair (UTP)

Shielded Twisted Pair (STP)


Summary - I

Line configuration is the manner in which the devices are attached to the communication links

Topology is the way in which the devices are connected together in the network

Two types of line configuration are: Point-to-point Multipoint

Five basic topologies include Bus Star


Summary - II Ring Tree Mesh

The types of network are Local Area Network Metropolitan Area Network Wide Area Network

Modes of transmission Simplex Half Duplex Full Duplex


Summary - III

The hierarchical network model designed by Cisco provides a reliable, scalable and cost effective way to transfer information

The three layers of the network model are: Core Distributional Access

Core layer is responsible for fast and reliable transportation of data on the network


Summary - IV

Distribution layer is responsible for routing and it manipulates the packets by queuing them

Access layer ensures that the packets are delivered to the destination computers

The Open Systems Interconnection (OSI) is the layered model for the network systems, which enables computers in the network to communicate with each other

Application layer provides an interface for the user to interact with the application


Summary - V

The seven layers of the OSI model include: Application Presentation Session Transport Network Data Link Physical


Summary - VI

Presentation layer is responsible for the delivery of information

Session layer controls the communication between the applications on the hosts

Transport layer is responsible for source-to-destination delivery of the entire message

Ethernet Frames are used by the Data Link layer to transfer the packets of data from the Network layer

Physical layer is responsible to transmit a bit over the physical medium

Education

CCNA CHAPTER 1 BY jetarvind kumar madhukar