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Unformatted text preview: P layer to exchange error messages and other vital
information with the IP layer in another host or router. Chapter 6 looks at ICMP in more detail.
Although ICMP is used primarily by IP, it is possible for an application to also access it. Indeed
we'll see that two popular diagnostic tools, Ping and Traceroute (Chapters 7 and 8), both use
IGMP is the Internet Group Management Protocol. It is used with multicasting: sending a UDP
datagram to multiple hosts. We describe the general properties of broadcasting (sending a UDP
datagram to every host on a specified network) and multicasting in Chapter 12, and then
describe IGMP itself in Chapter 13.
ARP (Address Resolution Protocol) and RARP (Reverse Address Resolution Protocol) are
specialized protocols used only with certain types of network interfaces (such as Ethernet and
token ring) to convert between the addresses used by the IP layer and the addresses used by the
network interface. We examine these protocols in Chapters 4 and 5, respectively. 1.4 Internet Addresses
Every interface on an internet must have a unique Internet address (also called an IP address).
These addresses are 32-bit numbers. Instead of using a flat address space such as 1, 2, 3, and so
on, there is a structure to Internet addresses. Figure 1.5 shows the five different classes of
These 32-bit addresses are normally written as four decimal numbers, one for each byte of the
address. This is called dotted-decimal notation. For example, the class B address of the author's
primary system is 184.108.40.206.
The easiest way to differentiate between the different classes of addresses is to look at the first
number of a dotted-decimal address. Figure 1.6 shows the different classes, with the first number
in boldface. file:///D|/Documents%20and%20Settings/bigini/Docu...homenet2run/tcpip/tcp-ip-illustrated/introduc.htm (7 of 20) [12/09/2001 14.46.31] Chapter 1. Introduction Figure 1.5 The five different classes of Internet addresses.
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This test prep was uploaded on 04/04/2014 for the course ECE EL5373 taught by Professor Guoyang during the Spring '12 term at NYU Poly.
- Spring '12