Post date: Dec 12, 2014 3:06:31 PM
Local Area Network (LAN)
A LAN is usually privately owned and connects some hosts in single office, building and campus. A packet sent by a host to another host carries both the source host's and the destination host's addresses.
Wide Area Network (WAN)
A WAN has a wider geographical span, spanning a town, a state, a country even the world. WAN has two distinct examples today, point-to-point WAN and switched WAN.
Layered architecture
Layer 5 Application
Layer 4 Transport
Layer 3 Network
Layer 2 Data link
Layer 1 Physical
Application layer
The fifth layer of the TCP/IP protocol. It provides services to the user. Communication is provided using a logical connection, which means that two application layers assume that there is an imaginary direct connection through which they can send and receive messages.
Transport Layer
It is located between the application layer and the network layer. Besides, it providers services to the application layer and receive service from the network layer.
Network Layer
It is responsible for the host-to-host delivery of messages.
Data-link Layer
This layer is the territories of networks that when connected make up the Internet. These networks, wired or wireless, receive services and provide services to the network layer.
Physical Layer
The role of physical layer is to transfer the bits received from the data-link layer and convert the to electromagnetic signals for transmission. After the bits are converted to signals, the signals are delivered to the transmission media.
Router
It is used for routing. Although a router is always involved in one network layer, it is involved in n combinations of link and physical layers in which n is the number of links the router is connected to.
Switch
It used to connect the devices together to a computer network.
Providing Services
Since the application layer is the only layer that provides services to the Internet user, the flexibility of the application layer allows new application protocols to be easily added to the Internet, which has been occurring during the lifetime of the Internet.
File Transfer Protocol (FTP)
FTP is a standard protocol provided by TCP/IP for copying a fie from one host to another.
Domain Name System (DNS)
Generic domain labels
Country domains
Electronic mail (Email)
User Agent (UA) > Mail Transfer Agent (MTA) client > MTA server > Spooling > MTA client > Internet > MTA server > Boxes > Message Access Agent (MAA) server > MAA client > UA