ipv4

  • 32 bit addresses divided into 8 bit blocks.
  • Has private address range and multicast address range.

Classful networking

  • 0xxxxxxx.x.x.x is one network. Called class A.
    • Has 128 possible networks. Size of network is 224
    • Has subnet mask equal to 8.
  • Similarly 10xxxxxx.x.x.x is another network. Class B.
    • Has 214 networks. Network size decreases inversely.
    • Has subnet mask equal to 16. -Similarly class C has subnet of 24.
  • Only allowed for 254 networks.

Fun fact: ARPAnet was 10.x.x.x

private address range

Block SizeRangeBit maskClassful description
24-bit10.0.0.0 - 10.255.255.2558One class A network
20 bit172.16.0.0 - 172.31.255.2551216 contiguous class B networks
12 bit192.168.0.0 - 192.168.255.25516256 contiguous class C networks

Loopback interface

  • Special case of private addresses.
  • Packets never leave the host.
  • 127.0.0.0/8 is the address space reserved for ipv4.

IP Broadcast

  • In IPv4 it has a special address. This was used by interfaces to send messages to all networks connected to a particular subnet.
  • In dhcp, if the broadcast address of the subnet is not defined, then a DHCPDISCOVER message is sent to the address 255.255.255.255.
  • This again does the same job of keeping the broadcast message within the same subnet.
  • The broadcast address is otherwise calculated as follows: - Take the first subnet bits of the network. Let them be as they are. - Change the remaining trailing bits to 1.

  • tcp
    • Transmission Control Protocol. Originated along with ipv4 and hence the entire system is called TC/IP.