Writes a note on the function of network layer.
The network layer is responsible for establishing, maintaining and terminating network connections. It manages the delivery of data form source to destination.
Network layer determines logical path between sender and the receiver. There may be many networks between two computers to the destination computer.
What is the function of data link layer?
The data link layer is responsible for the reliability of the physical link established at layer 1. Data link must decide the following:
1. Framing: The data link layer divides the stream of bits into manageable data units called frames.
2. Flow Control: The rate of sending data can be more than the of receiving data link layer imposes flow control mechanism to prevent it.
3. Errors Control: The data link layer detects and retransmits damaged or lost frames. It also prevents the duplication of frames.
4. Access Control: If two or more devices are connected to the same link, data link layer determines which device has control over the link at a given time.
Briefly describe the function of physical layer.
The physical layer is the bottom layer of the OSI model. It transmits stream of bits and defines how the data is transmitted over the network and what control signals are used. Its main function is to control how stream of bits is send and received over the physical medium. Physical layer must decide the following:
1 Characteristic of Media: The physical layer defines the characteristics and type of transmission medium.
2 Representation of Bits: The bits are encoded into electrical signals for transmission.
3 Data Rate: physical layer defines the number of that will be sent in each second.
4 Transmission Mode: The physical layer defines the direction of transmission between two devices: simple, half-duplex or full-duplex.