Network Layer Characteristics

Network Layer Characteristics

1. Network Layer

   • IPv4, IPv6
     • Main Communication Protocols
   • Other Protocols As:
     • OSPF
       • Open Shortest Path First
     • ICMP
       • Internet Control Message Control
   • For End-To-End communications, Performs four operations:
     • Addressing End Devices
       • End Devices must be configured with unique IP address
     • De-encapsulation
       • At Network Layer, host performs IP header check.
         • If Matches, then it's removed
         • The resulting Layer is passed up to appropiate service
     • Routing
       • Services to direct packets to host on other network. Processed by router. Router's role is select best path. Packets cross many routers. Each cross performed is called "hop".
     • Encapsulation
       • Encapsulates from Segment to Packet. Performed by Source IP Packet
         • Adds:
           • IP Address
             • Source
             • Destination
           • Ip Header
   • Specifies packet structure and processing to carry data from one host to another.

2. IP Encapsulation

   • IP encapsulates by adding an IP header
     • IP header is used to deliver the packet to the destination host
       • Examined by layer 3 devices (Routers and some switches)
   • Transport layer segments can be readily packaged by IPv4 or IPv6
   • IP remains the same from source hosto to destination host
   • NAT
     • Network Address Translation

3. Characteriscitcs of IP

   • Necesary for delivering packets from source to destination
   • Not designed for tracking and managing the flow of packets
   • Connectionless
     • No connection established (dedicated end-to-end connection) before sending data packets. No initial exchange of control information.
   • Best Effort
     • IP unreliable because packet delivery not guaranteed
     • Does not require additional fields in the header to maintain an established connection
   • Media Independent
     • Independent of the medium carrying the data
     • IP
       • Does not have the capability to manage and recover from undelivered or corrupt packets
       • Sent with information about the location of delivery
     • The OSI data link layer is responsible for taking an IP packet and preparing it for transmission over the communications medium.
     • MTU
       • Maximun Transmission Unit
       • Maximum size of the PDU that each medium can transport
     • Fragmentation
       • Causes latency
       • Splitting IPv4 packet