Exploring Internet Layer Protocols
Two-thirds of the TCP/IP protocol suite operates on the Internet layer, so a lot of activity occurs here. This is the layer where routing occurs and where the resolution of IP addresses to MAC addresses occurs. There are also two protocols on this layer that we haven't really discussed yet: ICMP and IGMP. In this section, all of that is covered as well as the interactions of the protocols on the TCP/IP Internet layer “team.”
Internet Protocol (IP) is a connectionless protocol that depends on TCP when connection-oriented operations are required. The IP header is attached to the segment containing everything that was added at the Application and Transport layers. This container is called an IP datagram ...