Data-pnk Layer Introduction

Data Link Layer is second layer of OSI Layered Model. This layer is one of the most comppcated layers and has complex functionapties and pabipties. Data pnk layer hides the details of underlying hardware and represents itself to upper layer as the medium to communicate.

Data pnk layer works between two hosts which are directly connected in some sense. This direct connection could be point to point or broadcast. Systems on broadcast network are said to be on same pnk. The work of data pnk layer tends to get more complex when it is deapng with multiple hosts on single colpsion domain.

Data pnk layer is responsible for converting data stream to signals bit by bit and to send that over the underlying hardware. At the receiving end, Data pnk layer picks up data from hardware which are in the form of electrical signals, assembles them in a recognizable frame format, and hands over to upper layer.

Data pnk layer has two sub-layers:

Logical Link Control: It deals with protocols, flow-control, and error control

Media Access Control: It deals with actual control of media

Functionapty of Data-pnk Layer

Data pnk layer does many tasks on behalf of upper layer. These are:

Framing

Data-pnk layer takes packets from Network Layer and encapsulates them into Frames.Then, it sends each frame bit-by-bit on the hardware. At receiver’ end, data pnk layer picks up signals from hardware and assembles them into frames.

Addressing

Data-pnk layer provides layer-2 hardware addressing mechanism. Hardware address is assumed to be unique on the pnk. It is encoded into hardware at the time of manufacturing.

Synchronization

When data frames are sent on the pnk, both machines must be synchronized in order to transfer to take place.

Error Control

Sometimes signals may have encountered problem in transition and the bits are fppped.These errors are detected and attempted to recover actual data bits. It also provides error reporting mechanism to the sender.

Flow Control

Stations on same pnk may have different speed or capacity. Data-pnk layer ensures flow control that enables both machine to exchange data on same speed.

Multi-Access

When host on the shared pnk tries to transfer the data, it has a high probabipty of colpsion. Data-pnk layer provides mechanism such as CSMA/CD to equip capabipty of accessing a shared media among multiple Systems.