The network layer or layer 3 of the OSI (Open Systems Interconnection) model is concerned delivery of data packets from the source to the destination across multiple hops or links. It is the lowest layer that is concerned with end − to − end transmission.
- Store and Forward Packet Switching
- Services to Transport Layer
- Providing Connection Oriented Service
- Providing Connectionless Service
1. Store and Forward Packet Switching
The host sends the packet to the nearest router. This packet is stored there until it has fully arrived once the link is fully processed by verifying the checksum then it is forwarded to the next router till it reaches the destination. This mechanism is called “Store and Forward packet switching.”
2.Services to Transport Layer
Through the network/transport layer interface, the network layer transfers its patterns services to the transport layer. These services are described below. But before providing these services to the transfer layer, the following goals must be kept in mind:
- Offering services must not depend on router technology.
- The transport layer needs to be protected from the type, number, and topology of the available router.
- The network addresses for the transport layer should use uniform numbering patterns, also at LAN and WAN connections.
3.Providing Connection Oriented Service
Packets are termed as “datagrams” and corresponding subnets as “datagram subnets”. When the message size that has to be transmitted is 4 times the size of the packet, then the network layer divides into 4 packets and transmits each packet to the router via. a few protocols. Each data packet has a destination address and is routed independently irrespective of the packets.
4.Providing Connectionless Service
To use a connection-oriented service, first, we establish a connection, use it, and then release it. In connection-oriented services, the data packets are delivered to the receiver in the same order in which they have been sent by the sender.
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