Network Layer

It is the network layer's job to figure out the network topology, handle routing and to prepare data for transmission. The network layer is concerned with the following primary functions:

  1. Communication with the Transport layer above.
  2. Encapsulation of Transport data into Network layer Protocol Data Units.
  3. Management of connectivity and routing between hosts or networks.
  4. Communication with the data link layer below.

Examples of network layer protocols include:

  • Internet Protocol
  • Internet Control Message Protocol (ICMP or "ping")
  • Internet Gateway Management Protocol (IGMP)
  • IPX/SPX



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Application
Presentation
Session
Transport
Network
Data Link
Physical
Function of Layer Protocols Network Components
  • translates logical network address and names to their physical address (e.g. computername ==> MAC address)
  • responsible for:
    • addressing
    • determining routes for sending
    • managing network problems such as packet switching, data congestion and routing
  • if router can’t send data frame as large as the source computer sends, the network layer compensates by breaking the data into smaller units. At the receiving end, the network layer reassembles the data
  • think of this layer stamping the addresses on each train car
 		IP; ARP; RARP, ICMP; RIP; OSFP;
IGMP;

IPX

NWLink

NetBEUI

OSI

DDP

DECnet 		Brouter

Router

Frame Relay Device

ATM Switch

Advanced Cable Tester



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