TCP/IP

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Application layer

The function of this layer generally is to sand and receive the data. We will explain some applications.
1- DHCP → port no.67
This program assign dynamic IP's "pc address" to
The hosts instead of static IP's.
2- Web → port no.80
This program publishes the web sites. So that the
Web client programs like internet explorer can
Request the web sites from web servers.
3- DNS → port 53
Mapping from hostname to IP address
4- FTP → port 21
Used for file transfer
5- SMTP → port 25
Used for sending mail
6- POP3 → port 110
Used for receive mails.
7- telnet → port 23
Used for remote login.
Host to host layer

1> transmission control protocol "TCP"
Features
Connection setup by 3- way
handshaking

1. connection oriented protocol data transfer
connection release by 4- way
hand shaking
2. reliable protocol


Internet layer

IP protocol receive segment or datagram then it add IP header which contain source IP and destination IP and protocol number " 6→TCP & 17→ udp".
The data now called packet.

Network access layer

The common protocol in this layer is Ethernet. Which add MAC header and trailer.
The MAC headers contain source MAC and destination MAC.