What are the layers in OSI Reference Models? Describe each layer briefly?
Given below are the seven layers of OSI Reference Models:
(1) Physical Layer (Layer 1): Physical Layer converts data bits into electrical impulse or radio signals. Example: Ethernet.
(2) Data Link Layer (Layer 2): At the Data Link layer, data packets are encoded and decoded into bits and it provides a node to node data transfer. Data Link Layer also detects the errors that occurred at Layer 1.
(3) Network Layer (Layer 3): Network Layer transfers variable length data sequence from one node to another node in the same network. This variable-length data sequence is also known as “Datagrams”.
(4) Transport Layer (Layer 4): It transfers data between nodes and also provides acknowledgment of successful data transmission. It keeps track of transmission and sends the segments again if the transmission fails.
(5) Session Layer (Layer 5): Session Layer manages and controls the connections between computers. It establishes, coordinates, exchange and terminates the connections between local and remote applications.
(6) Presentation Layer (Layer 6): It is also called as “Syntax Layer”. Layer 6 transforms the data into the form in which the application layer accepts.
(7) Application Layer (Layer 7): This is the last layer of OSI Reference Model and is the one which is close to the end user. Both end-user and application layer interacts with the software application. This layer provides services for email, file transfer etc.