network fundamental 101

8/10/2019 Network Fundamental 101

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2.3.2 The Layers of the TCP/IP reference model


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Rick Graziani [email protected]

Application

Transport

Internet

Network Access

Application Layer The designers of TCP/IP felt that the higherlevel protocols should include the session

and presentation layer details. They simplycreated an application layer that handleshigh-level protocols, issues ofrepresentation, encoding, and dialogcontrol. The TCP/IP combines allapplication-related issues into one layer,

and assures this data is properly packagedfor the next layer. This is also referred to asthe process layer.



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Application

Transport

Internet

Network Access

Transport Layer The transport layer deals with the quality-

of-service issues of reliability, flow control,and error correction.



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Application

Transport

Internet

Network Access

Internet Layer The purpose of the Internet layer is to send

source packets from any network on theinternetwork and have them arrive at thedestination independent of the path andnetworks they took to get there.


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TCP/IP model


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Some of the common protocols specified by the TCP/IP reference model layers. Some of the

most commonly used application layer protocols include the following: File Transfer Protocol (FTP) Hypertext Transfer Protocol (HTTP) Simple Mail Transfer Protocol (SMTP) Domain Name System (DNS) Trivial File Transfer Protocol (TFTP)

The common transport layerprotocols include: Transport Control Protocol (TCP) User Datagram Protocol (UDP)

The primary protocol of theInternet layer is: Internet Protocol (IP)

TCP/IP model


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Networking professionals differ in their opinions on which model to use. Due to thenature of the industry it is necessary to become familiar with both. Both the OSIand TCP/IP models will be referred to throughout the curriculum. The focus will

be on the following: TCP as an OSI Layer 4 protocol IP as an OSI Layer 3 protocol Ethernet as a Layer 2 and Layer 1 technologyRemember that there is a difference between a model and an actual protocol that

is used in networking. The OSI model will be used to describe TCP/IP

protocols.

2.3.3 TCP/IP Protocol Graph


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TCP/IP model


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Networking professionals differ in their opinions on which model to use. Due to thenature of the industry it is necessary to become familiar with both. Both the OSIand TCP/IP models will be referred to throughout the curriculum. The focus will

be on the following: TCP as an OSI Layer 4 protocol IP as an OSI Layer 3 protocol Ethernet as a Layer 2 and Layer 1 technologyRemember that there is a difference between a model and an actual protocol that

is used in networking. The OSI model will be used to describe TCP/IP

protocols.

2.3.4 Comparison of the OSI model and the TCP/IP model


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2.3.4 Comparison of the OSI model and the TCP/IP model


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both have layersboth have application layers, though they include very different servicesboth have comparable transport and network layerspacket-switched (not circuit-switched) technology is assumednetworking professionals need to know both

TCP/IP combines the presentation and session layer issues into its applicationlayer

TCP/IP combines the OSI data link and physical layers into one layerTCP/IP appears simpler because it has fewer layersTCP/IP protocols are the standards around which the Internet developed

Detailed encapsulation process


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If one computer (host A) wants to send data to another computer(host B), the data is packaged through a process calledencapsulation

As the data packet moves down through the layers of the OSImodel, it receives headers, trailers, and other information.



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Networks must perform the following five conversion steps in order toencapsulate data:

1. Build the data.2. Package the data for end-to-end transport. 3. Add the network IP address to the header.4. Add the data link layer header and trailer. 5. Convert to bits for transmission.

Data Encapsulation Example


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ApplicationHeader + data

p p

Let us focus on the Layer 2, Data Link, Ethernet Frame fornow.

010010100100100100111010010001101000

Application Layer

Layer 4: Transport Layer

Layer 3: Network Layer

Layer 2:NetworkLayer

Layer 1: PhysicalLayer

Encapsulation


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Encapsulation

network fundamental 101

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