computer network architecture into 7 layers in a logical progression.
binary data, and routing of these data across networks. Higher levels cover network requests and responses, representation of data, and network protocols, as seen from a user's point of view.
The OSI model was originally conceived as a standard architecture for building network systems, and many popular network technologies today reflect the layered design of OSI.
1 Physical Layer
bits from the Physical layer of the sending (source) device over network communications media to the Physical layer of the receiving (destination) device.
repeaters are standard network devices that function at the Physical layer, as are cable connectors.
At the Physical layer, data is transmitted using the type of signaling supported by the physical medium: electric voltages, radio frequencies, or pulses of infrared or ordinary light.
2 Data Link Layer
MAC addresses for Ethernet networks, controlling access of network devices to the physical medium.
Because the Data Link layer is the most complex layer in the OSI model, it is often divided into two parts: the Media Access Control sub-layer and the Logical Link Control sub-layer.
3 Network Layer
The Network layer adds the concept of routing above the Data Link layer. When data arrives at the Network layer, the source and destination addresses contained inside each frame are examined to determine if the data has reached its final destination. If the data has reached the final destination, layer 3 formats the data into packets delivered to the Transport layer. Otherwise, the Network layer updates the destination address and pushes the frame down to the lower layers.
Neighbor Discovery Protocol (NDP).
4 Transport Layer
network protocols. Different transport protocols may support a range of optional capabilities, including error recovery, flow control, and support for re-transmission.
5 Session Layer
The Session Layer manages the sequence and flow of events that initiate and tear down network connections. At layer 5, it is built to support multiple types of connections that can be created dynamically and run over individual networks.
6 Presentation Layer
The Presentation layer has the simplest function of any piece of the OSI model. At layer 6, it handles syntax processing of message data such as format conversions and encryption/decryption needed to support the Application layer above it.
7 Application Layer
HTTP packages the data needed to send and receive web page content. This layer 7 provides data to (and obtains data from) the Presentation layer.