On the surface, network or the internet seems like a simple thing. What we do is just connecting a network cable or connect to a wifi coverage to connect to the internet. But, the internet/ network relays on lots of devices, software, standards, technologies and much more things.
Basically for the easy understanding of a network and how two or more computers inter communicate, there are few models introduced. Below are some of famous models listed.
1. The TCP/IP Model
2. OSI Network Model
pic from here : http://ptgmedia.pearsoncmg.com/images/art_wilkins_ositcpmdly/elementLinks/fig2_wilkins_osi-and-tcp-ip.jpg
1.The TCP/IP Model
This model also called as DoD model, since this was introduced by the Department
of Defence, US in the early stages of the internet. In this model, they used TCP/IP protocols to interconnect computers. This model described using 4 layers.
1.1. Host to Network Layer
1.2. Internet Layer
1.3. Transport Layer
1.4. Application Layer
1.1. Host to Network Layer
The protocol, TCP run on this layer. Varies host to host and network to
network.
1.2. Internet Layer
This layer holds the whole architecture together. Allows the host devices to
insert packets to the network. IP runs on this layer. Data packet sending and receiving order differs. Helps data packets to travel independently to the destination IP.
1.3. Transport Layer
Decides the transmission method whether serial or parallel. Multiplexing,
segmenting or splitting on the data done by this layer. This layer divides the data into small packets to send. Each packet contains receivers IP, senders IP and the data which should be sent to the other end.
1.4. Application Layer
This layer runs on the top of other layers and interacts with the user.
Browsers, and some top level protocols runs on this layer.
The above method was the very first model introduced to understand the network and later, the International Organisation for Standardisation(ISO) to advanced understanding and standardisation. This model called “Open System Interconnection(OSI) Reference Model” and it has 7 layers.
2.1. Physical Layer
2.2. Data Link Layer
2.3. Network Layer
2.4. Transport Layer
2.5. Session Layer
2.6. Presentation Layer
2.7. Application Layer
2.1. Physical Layer
This contains the physical cabling through the network. Twisted pair, Fibre
Optic are some types of cables used to interconnect computers.
2.2. Data Link Layer
This layer provides node to node data transfer.MAC and LLC runs and MAC
responsible for controlling how devices in a network gain access to medium and permission to transmit it. LLC responsible for identifying Network layer protocols and then encapsulating them and controls error checking and frame synchronisation.
2.3. Network Layer
This layer fulfils the requirement of sending data packets to another LAN, or
out to our physical layer. So, this completes its duty on two major sides, Addressing and Routing. IP addressing and Gateways, Subnet masking and calculating and detecting the data packet to the own computer or to another computer etc.
2.4. Transport Layer
This layer guarantees the successful delivery of the data packet to the
destination. Sending the data packet and getting the acknowledgement from receiver is the basic method of verifying the successful delivery. This is done by TCP which runs on Transport Layer.
2.5. Session Layer
This layer manages the sessions runs on computer. As an example if we use
two tabs on our web browser and one has only images and other one has letters. Then it cant be images on text tab and cant be texts on image tab. Like that those sessions divided and managed by this layer.
2.6. Presentation Layer
This layer responsible for displaying the same thing the server sent to the
client and inverse too. Different computers uses different technologies and methods. So there can be some crashes between them because of different methods. This layer identifies the errors and mistakes and delivers the same thing the server sent to the client.
This layer runs on the top of other layers and interacts with the user.
Browsers, and some top level protocols runs on this layer.
The above method was the very first model introduced to understand the network and later, the International Organisation for Standardisation(ISO) to advanced understanding and standardisation. This model called “Open System Interconnection(OSI) Reference Model” and it has 7 layers.
2.1. Physical Layer
2.2. Data Link Layer
2.3. Network Layer
2.4. Transport Layer
2.5. Session Layer
2.6. Presentation Layer
2.7. Application Layer
2.1. Physical Layer
This contains the physical cabling through the network. Twisted pair, Fibre
Optic are some types of cables used to interconnect computers.
2.2. Data Link Layer
This layer provides node to node data transfer.MAC and LLC runs and MAC
responsible for controlling how devices in a network gain access to medium and permission to transmit it. LLC responsible for identifying Network layer protocols and then encapsulating them and controls error checking and frame synchronisation.
2.3. Network Layer
This layer fulfils the requirement of sending data packets to another LAN, or
out to our physical layer. So, this completes its duty on two major sides, Addressing and Routing. IP addressing and Gateways, Subnet masking and calculating and detecting the data packet to the own computer or to another computer etc.
2.4. Transport Layer
This layer guarantees the successful delivery of the data packet to the
destination. Sending the data packet and getting the acknowledgement from receiver is the basic method of verifying the successful delivery. This is done by TCP which runs on Transport Layer.
2.5. Session Layer
This layer manages the sessions runs on computer. As an example if we use
two tabs on our web browser and one has only images and other one has letters. Then it cant be images on text tab and cant be texts on image tab. Like that those sessions divided and managed by this layer.
2.6. Presentation Layer
This layer responsible for displaying the same thing the server sent to the
client and inverse too. Different computers uses different technologies and methods. So there can be some crashes between them because of different methods. This layer identifies the errors and mistakes and delivers the same thing the server sent to the client.
2.7. Application Layer
All the web browsers, file transfer software and email clients also runs on this
layer. So this layer directly interconnects with the user and this is what user see when he or she uses the network.
Now lets have a small comparison between TCP/IP model and OSI model.
All the web browsers, file transfer software and email clients also runs on this
layer. So this layer directly interconnects with the user and this is what user see when he or she uses the network.
Now lets have a small comparison between TCP/IP model and OSI model.
pic from here : http://i.stack.imgur.com/CG9lg.jpg
Hope you got some idea and sound knowledge on TCP/IP Model and OSI Model. Feel free to comment and share your ideas. Share with your friends. :)
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