Introduction To TCP/IP Protocol

The Transmission Control Protocol/Internet Protocol (TCP/IP) was created by the Department of Defense (DoD) in 1973 to ensure the data integrity and also to identify to correct person during the catastrophic war. In 1983, TCP/IP replaced all the old protocols and got authorized for the any type of communication taking place in ARPAnet.

TCP/IP is the set of rules which contains unique address to identify the particular device connected to the network. Now as TCP/IP protocol suite  was created by DOD, the model which TCP/IP follows for communication is also called DOD Model. Dod Model or the TCP/IP protocol suite is very similar to the OSI Reference Model. DoD Model consists of 4 layer which are as follows:

1. Process/Application Layer
2. Host-to-Host Layer
3. Internet Layer
4. Network Access Layer

The following figure shows the comparison between DoD Model and the OSI Reference Model:

 

The 4 layers of DoD Model does the same thing which is done by the 7 layers of the OSI Reference Model.

The Process/Application layer controls user interface which is done by the above three layers of the OSI Model. The Host-to-Host layer  maintains packet sequencing and data integrity. The Internet layer is similar to the Network layer of the OSI reference Model and does the work of routing the packets among the number of networks. The Network Access layer maintains the data exchange between host and the network which is equivalent to the work done by the DataLink and Physical Layer of the OSI reference Model.

The services provided by the different layer of the Dod model are as follows:

Process/Application Layer

• Telnet - Telnet allows the user to access the resources of another machine remotely
• File Transfer Protocol (FTP) – FTP protocol allows the user to transfer the files from the FTP server to the machine used by the user. It is actually used for the transformation of file.
• Trivial File Transfer Protocol (TFTP) – This protocol is similar to the FTP but has no directory browsing abilities, it can just send and receive a file.
• Network File System (NFS) – This protocol allows the user to share the files between the computers.
• Simple Mail Transfer Protocol (SMTP) – This protocol is used to send and receive a mail and it uses spooled method of mailing system.
• Line Printer Daemon (LPD) – This protocol is used for the printer sharing.
• X Window – Designed for client/server operations.
• Simple Network Management Protocol (SNMP) – Designed for gathering the various important information of the network devices.
• Hypertext Transfer Protocol (HTTP) – Used to view websites and to communicate between server and host.
• Hypertext Transfer Protocol Secure (HTTPS) – It does the same work like HTTP but this protocol uses SSL Secure Sockets Layer.

Host-to-Host Layer

1. Transmission Control Protocol (TCP) – This protocol is used for full duplex communication, and also for small error checking.
2. User Datagram Protocol (UDP) – UDP is used for the transportation of the message or information which doesn't require any delivery.

The Internet Layer

1. Internet Protocol (IP) – It consists of physical address as well as logical addresses to identify the machines.
2. Internet Control Message Protocol (ICMP) – This protocol gives information about network problems.
3. Address Resolution Protocol (ARP) – This protocol finds out the Hardware Address of the host from known IP Address.

The Network Access Layer

1. Ethernet – This protocol is used for the communication taking place between two hosts via Ethernet cables.
2. Fast Ethernet – This protocol is same as Ethernet but provides more speed then the Ethernet.

And Network Access Layer contains information of physical addresses and also it converts data into digital form and transports it.

This was whole introduction about the TCP/IP and its services

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How to Connect Two Computers in LAN to Play games or for data transfer

LAN gaming is more fun than the games played with single player. So if want to play the multiplayer game or to transfer the data through LAN, just need one LAN CABLE such as follows:

Now attach this LAN cable to the LAN ports of both the Computers. To understand better I have one picture to show.

This is the picture of two PC connected in a LAN via LAN cable.

Now you just need to do is to set IP Addresses of both the PC’s as follows:

• Press Windows Button + R to open Run.
• Copy the code from here control.exe /name Microsoft.NetworkAndSharingCenter , which are in red color and just paste it in the Run window opened and press Enter Key.
• Then after another window will get opened, in that window, go forward to Change adapter settings > Local Area Connection
• Now right click on Local Area Connection and go to properties.
• Then after click on Internet Protocol Version 4 (TCP/IPv4), in that choose the radio button named Use the following IP address
• Now enter the IP address and subnet mask as shown in above picture in both the computers.
• If want to connect more number of computers then go on increasing the last digit of IP.
• You can use other IP addresses also. But these are Class C IP they are called fake IP means not used in Commercial Field. So it is better to use this IP.

Important Note:  Firewall of both the computers must be turned off as it blocks some of the connections or some Packets.

How to turn off the Firewall of Computer in Windows 7:

• Open Run and copy the command from here Firewall.cpl with red characters and paste it in the run window and press Enter Key.
• Now click on Turn Windows Firewall ON or OFF in the which got opened.
• Now configure the options as shown in the figure below

Press okay and you are done. Turning off the firewall will allow you to play the games smoothly and also to transfer the data smoothly.

To transfer data from one pc to another pc just type the IP Address of computer from which you want to transfer data to another computer with double slash \\ (backward slash) like \\192.168.10.1. and press Enter. Shared files will be shown in your computer window and you can copy the data you need and transfer it easily with a very nice speed.

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The OSI(Open System Interconnection) Reference Model

The OSI reference model is layered step by step discussion of how to communication process takes place. There are seven layers in OSI reference model, each are made for its own functions. The OSI model isn’t physical, but it guides the developer to create application or hardware devices.

The seven layers of OSI Reference Model are as follows:

Now these seven layers of OSI are divided into two groups according to their functionality.

• The top three layers decide how to communicate with each other and with users
• The bottom four layers decide how data is transferred from host to host

These both group are having different functionality. Upper layer with three layer don’t know anything about Network or Network Address or IP Address because that functionality belongs to the bottom four layers.

Now let us see the functionalities of each layers of OSI Reference Model

Application Layer (layer 7):

Application Layer provides user interface to use the application when needed. Actually application layer comes into picture only when it is needed. For example if a user wants to open a file using HTTP/FTP or any protocol, then Application Layer provides interface (for example say Internet Explorer or any Browser). Similarly it provides interface for sending messages, for database, for application services etc.

The Presentation Layer (layer 6):

The function of Presentation Layer is to present the data to Application Layer and also it is responsible for data translation.

It performs the tasks like compression, encryption, decryption, etc

The session Layer (layer 5):

The Session Layer separates the data of one application from another application. It controls the data. The main work of this layer is to provide Dialog Control between devices and node. It Offers simplex, duplex, half duplex and full duplex services.

The Transport Layer (layer 4):

This layer provides end to end data transport services. TCP/IP protocols works at this layer. This layer also provides services like acknowledgement, flow control and sequencing.

The Network Layer (layer 3):

We saw that routers are called layer 3 devices, because they works on Network Layer Functionality. This layer determines all the addresses on the network. Used to transport traffic between the devices connected. All the routing protocols works at this level. Addresses such as IPv4, IPv6, MAC address are known to the layer 3 devices.

The Data Link Layer (layer 2):

This layer provides data transmission and also detect errors or watches the network topology. So Data Link Layer will ensure that a message are delivered to proper device or not, using MAC Address.

It will also convert the messages into bits for physical layer so that physical layer can transmit further. And the message in pieces are called Data Frames. It also contains MAC address of destination as well as of source.

Switches and Bridges are the example that works at layer 2. Hence they are known as layer 2 devices.

The Physical Layer (layer 1):

The Physical Layer of source transmits the data to the destination physical layer in bit format. The data will be in the form of bits (0 or 1). This layer is also used to know the physical links connected to the network devices such as cables, Ethernet cables etc.

Hub is the example which works at layer 1. That is why it is known as Layer 1 device.

So this was all about OSI layer.

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