By Team ClassWork The basic function of network layer is to provide an end-to-end communications capability to the transport layer which lies above it. Network layer is the lowest layer that deals with end-to-end transmission
To achieve the goal, the network layer must know about the topology of the communication subnet ie. set of all routers and choose appropriate path through it Network layer also takes care of loading of the chosen root
The network layer protocols are concerned with the exchange of packets of information between transport layer entities.
• A packet is a group of bits that includes data bits plus source and destination addresses
.. The service provided by the network layer to the transport layer is called network
service
• The functions carried out by a layer are different from its services. Functions are those activities which are carried out by a layer in order to provide the services.
The network layer functions are carried out by adding a header to every Network Service Data Unit (SDU) forming Network Protocol Data Unit (NPDU). The header contains all the information necessary for carrying out functions.
1) It keeps track which MAC (Media Access Control, the unique number that each network card has) address to send le decides which system receives the information
2) It makes-routing of data through network from source to destination.
3) Virtual circuits are established in this layer.
4) It translates logical network address into physical machine address.
5) It breaks large packets into smaller so that it will be accepted by the frame of data
link layer.
6) Flow control of packetized information and congestion avoidance is concern of protocol.
7) It determine the quality of service (QOS) parameters.
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