TCP/IP is the most important model in the system structure. If you want to know more about howthe computer deal with the order which you input.You must study TCP/IP well.For example, now we want to surf online. input the website “www.cisco.com”. then the computer will change thewords to ASCII(just a example..) and send it to Application layer. Application layer receive the data, will add message to show where and how the data will send. Now the data have arrivedat transport layer, here the data will be made into segment and sent. When the segment reach Network layer, it will be made into packet and then sent to Data link layer. In the Data link layer,the packet become framing. Now the framing arrive Physical layer. “Hi,welcome. but I will send you to the host which named 'www.cisco.com'“ the Physical layer said. It is right? In fact , The physical layer don't know what the framing is. He justcan send bit message .
The Model of TCP/IP.
Application layer the highest layer in the structure and for offerring the service between the processes which user ordered. There are some protocol such as HTTP protocol ,FTP protocol, SMTP protocol ,etc..
Transport layer for the communication between two processes in the host. There are two types protocol. one is connectionless call TCP (Transmission Control Protocol) and other is connection-oriented call UDP(User Datagram Protocol) Network layer for transmission between the different hosts in the packet network. There are two action: make into packet and choose the suited routing. There is a protocol call Internet Protocol (IP) on the layer. Data link layer for making into framing . Physical layer for sending the bit..
Why to carve up the model like this? Maybe it can become more simple and easier to vindicate???

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