In networks, a communications protocol or network protocol is the specification of a series of rules for a particular type of communication. The Internet network is ba
sed on the TCP/IP reference model (Transmission Control Protocol/Internet Protocol) that takes its name from the two main protocols that regulate communication through this network.
TCP
TCP is a connection-oriented transport protocol that sends data as a byte stream without structure. Using sequence numbers and recognition messages, TCP can provide a shipping node with the delivery information about the packets transmitted to a destination node. Where data has been lost in transit from the source to the destination, the TCP can retransmit the data until either a rest condition is reached or until Successful delivery has been achieved.
IP
The IP is the primary protocol of layer 3 in the Internet group. In addition to routing between networks, IP provides the report of errors and fragmentation and new assembly of the information units called datagrams for transmission through networks with different maximum sizes of the data unit. The IP represents the heart of the set of Internet protocols.
The TCP / IP model specifies the protocols that govern communication between several nodes in the network. This communication is made at several levels, called "layers", each layer being responsible for a certain set of functions or tasks. The protocols of the different "layers" are not independent of each other, but use the protocols of the lower layer to develop their functions and offer their services to the protocols of the upper layer.
The layers are nested. Each layer is built on its predecessor. The number of layers and the variables with each type of network. However, in any red, the mission of each is to provide services to the upper layers to which they become transparent in the way in which those services are carried out. In this way, each layer must deal with its lower level, to whom it requests services, and at the higher level, to whom it returns results.
layers:
- layer 4 or application layer: application, assimilable to the layers: 5 (session), 6 (presentation) and 7 (application), of the OSI model. The application layer should include the details of the OSI session and presentation layers. They created an application layer that handles aspects of representation, coding and dialog control. Protocols: HTTP, FTP, POP3, SMTP, SNMP.
- layer 3 or transport layer: transport, assimilable to layer 4 (transport) of the OSI model. Protocols: TCP, UDP.
- layer 2 or internet layer: Internet, similar to layer 3 (network) of the OSI model. Protocols: IP, ICMP.
- layer 1 or access layer to the medium: access to the medium, similar to layer 2 (data link) and layer 1 (physical) of the OSI model. Protocols: include Ethernet for local area networks (LANs) and ARP.
Flow of information in the layers
This figure shows the flow of information down the TCP/IP protocol layers from the Sender to the Host.
frames received by a host go through the protocol layers in reverse. Each layer strips off the corresponding header information, until the data is back at the application layer.
This figure shows the flow of information up the TCP/IP protocol layers from the Host to the Sender.
frames are received by the Network Interface layer (in this case, an Ethernet adapter). The Network Interface layer strips off the Ethernet header, and sends the datagram up to the Network layer. In the Network layer, the Internet Protocol strips off the IP header and sends the packet up to the Transport layer. In the Transport layer, the TCP (in this case) strips off the TCP header and sends the data up to the Application layer.
Hosts on a network send and receive information simultaneously. The next figure more accurately represents a host as it communicates.
This figure shows data flowing both ways through the TCP/IP layers.
Advantages of TCP/IP
TCP/IP is not proprietary and, as a result, is not controlled by a single company. Therefore, the Internet protocol suite can be easily modified. It is compatible with all operating systems, so you can communicate with any other system. The Internet protocol suite is also compatible with all types of computer hardware and networks.
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