"There are five network layer protocols: ARP, RARP, IP, ICMP, and IGMP".
The author says that : ARP,RARP,ICMP,IGMP they will be encapsulated within an ip packet, "Local Area Network" Book by author Forouzan chapter 18 Page 389, under topic NETWORK LAYER, he says:
"At the network layer (or, more accurately , the internetwork layer), TCP/IP supports the internetwork protocol (IP). IP, in turn, contains four supporting protocols: ARP,RARP, ICMP,and IGMP. Each of these protocols is described later in this chapter".
If you look to the slide below , you can see that the fours protocol (ARP, RARP, ICMP, IGMP) within ip packet
And he says about ICMP:
"ICMP itself is a network layer protocol. However, its messages are not passed directly to the data link layer as would be expected. Instead, the messages are first encapsulated inside ip datagrams before going to the lower layer".
The author said that there are five protocols reside within network layer and encapsulated within ip packet , what about the other like RIP, OSPF, IS-IS, IGRP, EIGRP ,,,,etc ??