The network layer is concerned with getting packets from the source all the way to the destination with minimal cost. Unlike the data link layer which has more important goals like just moving frames from one end of a wire to another. The network layer is the lowest layer that deals with end-to-end transmission.
Network layer Design issues are as follows −
Store and forward packets switching
Services provided to the transport layer
Implementation of connectionless services
Implementation of connection oriented services
Comparison of virtual-circuit datagram networks
Now let us see one of the design issues of the network layer.
The services provided to the transport layer are as follows −
Logical Addressing − Network layer adds header to incoming packet which includes logical address to identify sender and receiver.
Routing − It is the mechanism provided by Network Layer for routing the packets to the final destination in the fastest possible and efficient way.
Flow control − This layer routes the packet to another way, If too many packets are present at the same time preventing bottlenecks and congestion.
Breaks Large Packets − Breaks larger packets into small packets.
Connection Oriented service − It is a network communication mode, where a communication session is established before any useful data can be transferred and where a stream of data is delivered in the same order as it was sent.
Connectionless Service − It is a data transmission method used in packet switching networks by which each data unit is individually addressed and routed based on information carried in each unit, rather than in the setup information of a prearranged, fixed data channel as in connection-oriented communication.
DataGram − A datagram is a basic transfer unit associated with a packet-switched network. The delivery, arrival time and order of arrival need not be guaranteed by the network.
A virtual circuit − It is a means of transporting data over a packet switched computer network in such a way that it appears as though there is a dedicated physical layer link between the source and destination end system of this data.