#todo: this was just translated from the original document, please revisit it
TCP/IP (Transmission Control Protocol/Internet Protocol) is the foundational suite of protocols used for communication on the Internet and many private networks. It provides a standardized framework that enables devices to communicate over diverse networks, ensuring reliable transmission of data.
This structure involves a hierarchy of protocols consisting of modules that interact with each other, each providing specific functionalities.
Each higher-level protocol is supported by the services provided by the lower level.
TCP (Transmission Control Protocol) handles breaking the data into packets, and everything that is related to the data transmission.
IP (Internet Protocol) on the other hand, just handles addressing, meaning it make sure that the packet arrives to the correct destination.
The TCP/IP protocol stack is composed of the following layers. Each layer of the source host encapsulates data received from the higher layer to transmit it to the lower layer; the destination host decapsulates data received from the lower layer to transmit it to the higher layer.
-
Application Layer: The logical connection between two application layers is end-to-end, meaning the layers exchange messages as if they were directly connected. Communication occurs between two processes: one process sends a request to another process and receives a response.
-
Transport Layer: The logical connection between two transport layers is also end-to-end. This layer receives the message from the application layer and encapsulates it into a segment (adding a header) and sends it, via logical connection, to the recipient’s transport layer. The main transport protocols are TCP and UDP.
-
Network Layer: Communication at this layer is host-to-host. The task of this layer is to deliver packets from the source host to the destination host. Along the path between source and destination, there may be routers, devices whose purpose is to find an optimal path for each packet. The main network protocol is IP, which encapsulates the segment received from the transport layer into a datagram.
-
Link Layer: When a router has determined the next link to use, the link layer transfers the packet through that link, which could be a LAN, WAN, or both wired or wireless. Packets encapsulated by this layer are called frames.
-
Physical Layer: The physical layer handles the transfer of individual bits of a frame across the connection. The connection between two physical layers is still a logical connection, as there is still a hidden layer, the actual transmission medium, which transfers electrical or optical signals (and not bits).
Multiplexing and Demultiplexing
- Multiplexing means that a protocol at one layer can encapsulate (one at a time) packets obtained from multiple protocols at the immediately higher layer.
- Demultiplexing means that a protocol can decapsulate and deliver packets to multiple protocols at the immediately higher layer. Each protocol must have a field in its header to identify which protocol the encapsulated packets belong to.
tags:#computer-networking resources: 1 - Introduzione.pdf