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OSI stands for open system interconnection. It is use to show logical process or data transmission. In this model define how to data delivered in a network. it has 7 layers.

(1)-Application Layer- Application layer is responsible for communicate between user and machine.

All the TCP/IP protocol work in this layer.

 

                        TCP/IP-

Service                                       Protocol                                   Port No.

Internet Browsing (HTTP)	Hyper Text Transfer Protocol	80
File Download & Up load (FTP)	File Transfer Protocol	20,21
Remote Access	Telnet	23
E-mail transfer (SMTP)	Simple Mail Transfer Protocol	25----------465
POP3	pop3-Post Office Protocol version 3	110----------995
Ip Address	Dynamic Host Configuration Protocol	60
Ip to name, name to ip (DNS)	Domain Name System	53

 

(2)-Presentation Layer- In this layer data in crept and decrypt compress and decompress.

(3)-Session Layer-It is create a link source to destination and it check the connectivity row.

(4)-Transport Layer-Is responsible for transfer the data source to destination. And here data will be convert in segment.

(5)-Network Layer-It check the connective to the machine and here segment will be convert in packet. Here ARP, RARP, ICMP Service work.

ARP- Address resolution protocol. (Ip address to Mac Address)

RARP-    Reverse Address Resolution Protocol. (Mac address to Ip address)

ICMP- Internet Control Massage protocol. (Ping A, B, C class ip)

Devices work on network layer-

Router, Multiplexer, Modem, bridge, NIT card, Hub.  

(6)-Data-link Layer-It has two sub layer. LLC logic link control-it is work on data link layer it is check the error and correct it.

 DEVICE- L2 switch, Modem, bridge, NIT card, Hub.   

MAC- Media access controller it is work on data layer and it check the error and correct it and packet will be convert in frame. 

(7)-Physical Layer- Here frame will be convert in binary.