IP (Internet protocol) is a Network Layer protocol (Layer 3) that considered ‘routed’ protocol. It addresses the Network Packets so that routing protocols like OSPF,BGP and RIP can correctly route the packet.
IP defines the IP addresses. IP address is a 32 bit number (4 octets). It comprises of Network and Host numbers. The higher order bits define the Network number as shown below.
There are 5 classes of IP addresses:
Class D is defined as Multicast. Address Range: 224 – 239
Class E is experimental. Address Range: 240 – 254
127.0.0.1 to 127.255.255.255 is defined as loop back address range.
Also, a range of IP addresses are reserved for Private use (i.e not routable in internet). They are
IPV6 uses 128 bit addresses and primarily introduced to address the depleting IPV4 addresses.