IPv4 Packet

IPv4 Packet

1. IPv4 Packet Header

   • Primary network layer communication protocol
   • Used to ensure a packet is delivered to its next stop
   • Consists of fields containing important information about the packet

2. IPv4 Packet Header Fields

   • Significant Fields:
     • Version
       • Contains a 4-bit binary set to 0100, identifies as IPv4 packet
     • DS
       • Diffrenciated Services or DiffServ
       • 8-bit field used to determinate priority of each packet
       • 6 bits are for DSCP , and last 2 bits for ECN
         • Differenciated Services Code Point
         • Explicit Congestion Notification
     • TTL
       • Time to Live
       • 8-bit binary value that is used to limit the lifetime of a packet
     • Protocol
       • Used to identify the next level protocol
       • 8-bit value indicates data payload that the packet is carrying. Enables network layer to pass data to upper layer
       • Common values:
         • ICMP: 1
         • TCP: 6
         • UDP: 17
     • Header Checksum
       • Used to detect corruption in the IPv4 header
     • Source IPv4 Address
       • 32-bit binary value
     • Destination IPv4 Address
       • 32-bit binary value
   • IHL
     • Internet Header Length
     • with Checksum, identifies and validate packet.