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WHAT IS THE L3 NETWORK LAYER?

The network layer is located at Layer 3 in the OSI reference model. This layer is responsible for routing data frames. The network layer provides the procedural and functional transport of packets of different lengths, divided into units over many different networks, from a source to a destination with quality of service (QoS).

NETWORK LAYER FUNCTIONS

CONNECTION MODEL : CONNECTIONLESS COMMUNICATION

IP communication, for example, is connectionless. When a source sends a data frame to a destination, the receiver does not have to acknowledge receipt of the data. Connection-oriented communication takes place at higher layers.

USER ADDRESSING

Each user on the network needs a unique address to know where they are in the network. This addressing is assigned hierarchically. For example, the addressing logic works with the addressing hierarchy in the form of number, street, neighborhood, district, city, country. With this information we can understand the address information of any place. IP addressing is similar to this. Users on the same network are in the same IP block.

MESSAGE FORWARDING : MESSAGE FORWARDING/TRANSFER

Since many networks have been divided into smaller networks and connected to other networks to form a wide-area network, packets are transmitted and routed between networks by devices called gateways or routers.

NETWORK LAYER PROTOCOLS

  • IPv4/IPv6, Internet Protocol
  • DVMRP, Distance Vector Multicast Routing Protocol
  • ICMP, Internet Control Message Protocol
  • IGMP, Internet Group Multicast Protocol
  • PIM-SM, Protocol Independent Multicast Sparse Mode
  • PIM-DM, Protocol Independent Multicast Dense Mode
  • IPsec, Internet Protocol Security
  • IPX, Internetwork Packet Exchange
  • RIP, Routing Information Protocol
  • DDP, Datagram Delivery Protocol