The Internet Protocol Layer

The Internet Protocol Layer is the second layer, and it primarily deals with addressing and routing functions. We can generally differentiate between the IP and Transport Layer with this analogy.

Here is a good analogy to help you understand. There is a truck full of packages that need to be transported from source A to destination B. So, essentially, the truck driver is responsible for the route to choose to reach the destination. The truck driver is the IP layer and the package inside the truck is the TCP. 

Two important fields within the IP layer are the Source IP and the Destination IP:

The core protocols in this layer are IP, ICMP, IGMP, and ARP.