LAYER 1 – The PHYSICAL Layer, LAYER 2 – The DATA LINK Layer And LAYER 3 – The NETWORK Layer

LAYER 1 – The PHYSICAL Layer

•  Converts bits into electronic signals for outgoing messages

•  Converts electronic signals into bits for incoming messages

•  This layer manages the interface between the computer and the network medium (coax, twisted pair, etc.)

•  This layer tells the driver software for the MAU (media attachment unit, e.g. network interface cards (NICs, modems, etc.))  that what needs to be sent across the medium

•  it is the bottom layer of the OSI model.

•The physical layer is responsible for movements of

individual bits from one hop (node) to the next.

(hope to hope delivery)

LAYER 2 – The DATA LINK Layer:

•  It accepts packets from network layer and convert it into individual frames so that they can be given to physical layer.

•  At the receiving end, this layer packages raw data from the physical layer into data frames for delivery to the Network layer.

•  At the sending end this layer handles conversion of data into raw formats that can be handled by the Physical Layer.

•The data link layer is responsible for moving 
frames from one hop (node) to the next.

LAYER 3 – The NETWORK Layer

•Handles addressing messages for delivery.

•Translate logical network addresses and names into their physical counterparts.

•Responsible for deciding how to route transmissions between computers.

•This layer also handles the decisions needed to get data from one point to the next point along a network path.

•This layer also handles packet switching and network congestion control.

•It makes data available for transport layer.

•The network layer is responsible for the 
delivery of individual packets from

•the source host to the destination host.