DAY1 01 Networking Fundamentals

8/6/2019 DAY1 01 Networking Fundamentals

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Network: is basically all the components (H/W &S/W) involved in connecting computer acrosssmall and large distance

Importance of Networks:E asy access and sharing of informationSharing of expensive devices and network

resourcesModern Technologies (IP telephony, Videoon Demand, .etc)

Networking Technologies


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Network components

Network has three main componentsC omputers (servers and hosts)- Source of applications (network aware applications)- ex: HTTP (Hyper Text Transmission Protocol),

FTP (File Transfer Protocol),SNMP (Simple Network Management Protocol)Telnet

Network Devices- Devices that interconnect different computers together

- ex: Repeaters, hub, bridge, switch, router, NIC

and modemsC onnectivity

- Media that physically connect the computers and network devices- ex: Wireless and cables


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Network Topologies

Topology: How devices are connected together Physical Topology: It describes how devices are physically cabledLogical Topology: It describes how devices communicate acrossphysical topology


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B us Topology

A bus topology uses a single backbone cable that isterminated at both ends.

All the hosts connect directly to this backbone.


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Star Topology

A star topology connects all cables to a central point of concentration.


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E xtended Star Topology

An extended star topology links individual stars together byconnecting the hubs and/or switches.This topology can extendthe scope and coverage of the network.


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Hierarchical Topology

A hierarchical topology is similar to an extended star.


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Mesh Topology

A mesh topology is implemented to provide as muchprotection as possible from interruption of service.E ach host has its own connections to all other hosts.

Although the Internet has multiple paths to any onelocation, it does not adopt the full mesh topology.


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Network Types

LAN (Local Area Network):It is a group of network components that workwithin small area

MAN (Metropolitan Area Network):It is a group of LANs that are interconnectedwithin small area

WAN (Wide Area Network):It is a group of LANs that are interconnectedwithin large area


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OS I model

To address the problem of networks increasing in sizeand in number, the International Organization for Standardization (ISO) researched many networkschemes and recognized that there was a need tocreate a network model that would help networkbuilders implement networks that could communicate

and work together and therefore, released the OSIreference model in 1984.


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The OSI Reference Model

7 Application

6 Presentation

5 S ession

4 Transport

3 Network

2 Data Link1 Physical

The OS I Model will beused throughout your entire networking

career!

Memorize it!


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Layer 7 - The Application Layer

7 Application

6 Presentation

5 S ession

4 Transport

3 Network


This layer deal withnetworking applications.

Examples:y Emaily Web browsers

PDU - User Data


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Layer 6 - The Presentation Layer

7 Application

6 Presentation

5 S ession

4 Transport

3 Network


This layer is responsiblefor presenting the data inthe required format whichmay include:y Encryptiony C ompression

PDU - Formatted Data


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Layer 5 - The Session Layer

7 Application

6 Presentation

5 S ession

4 Transport

3 Network


This layer establishes,manages, and terminatessessions between twocommunicating hosts.

Example:y C lient S oftware

( Used for logging in)

PDU - Formatted Data


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Layer 4 - The Transport Layer

7 Application

6 Presentation

5 S ession

4 Transport

3 Network


This layer breaks up thedata from the sending hostand then reassembles it inthe receiver.

It also is used to insurereliable data transport

across the network.PDU - S egments


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Layer 3 - The Network Layer

7 Application

6 Presentation

5 S ession

4 Transport

3 Network


S ometimes referred to as the C isco Layer.

Makes Best PathDetermination decisionsbased on logical addresses(usually IP addresses).

PDU - Packets


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Layer 2 - The Data Link Layer

7 Application

6 Presentation

5 S ession

4 Transport

3 Network


This layer provides reliabletransit of data across aphysical link.

Makes decisions based onphysical addresses (usuallyMAC addresses).

PDU - Frames


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Layer 1 - The Physical Layer

7 Application

6 Presentation

5 S ession

4 Transport

3 Network


This is the physical mediathrough which the data,represented as electronicsignals, is sent from the

source host to thedestination host.

Examples:y C AT5 (what we have)y C oaxial (like cable TV)y Fiber optic

PDU - Bits


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Encapsulation Process


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TC P/IP model

Application

Transport

Internet

NetworkAccess

7 Application

6 Presentation

5 S ession

4 Transport

3 Network

2 Data Link

1 Physical


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2 Models Side- B y-Side

Application

Transport

Internet

NetworkAccess

7 Application

6 Presentation

5 S ession

4 Transport

3 Network

2 Data Link

1 Physical


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The Application Layer

The applicationlayer of theTC P/IP modelhandles high-levelprotocols, issuesof representation,

encoding, anddialog control.


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The transport layer provides transport services fromthe source host to the destination host. It constitutesa logical connection between these endpoints of thenetwork. Transport protocols segment andreassemble upper-layer applications into the samedata stream between endpoints.The transport layer data stream provides end-to-endtransport services.

The Transport Layer


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The Internet Layer

The purpose of the Internet layer is toselect the best path through the network for packets to travel. The main protocol thatfunctions at this layer is the Internet

Protocol (IP). B est path determination andpacket switching occur at this layer.


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The Network Access Layer The network access layer is also called the host-to-network layer. It is the layer that is concerned with all of the issues that an IP packet requires to actually make aphysical link to the network media. It includes LAN andWAN details, and all the details contained in the OSIphysical and data-link layers. NOT E : ARP & RARP workat both the Internet and Network Access Layers.


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Documents

DAY1 01 Networking Fundamentals