Review of IP Addressing
65
Review of IP Addressing
O
ne of the most important topics in any discussion of TCP/IP is IP
addressing. An IP address is a numeric identifier assigned to each machine on
an IP network. It designates the location of a device on the network. An IP
address is a software address, not a hardware address. A hardware address
is hard-coded on a network interface card (NIC) and used for finding hosts
on a local network. IP addressing was designed to allow a host on one net-
work to communicate with a host on a different network, regardless of the
type of LANs in which the hosts are participating.
Before we get into the more difficult aspects of IP addressing, let's look at
some of the basics.
IP Terminology
In this chapter, we'll introduce you to a number of terms that are fundamen-
tal to an understanding of TCP/IP. We'll start by defining a few that are the
most important:
Bit One digit; either a 1 or a 0.
Byte Seven or eight bits, depending on whether parity is used. For the
rest of this chapter, always assume that a byte is eight bits.
Octet Always eight bits; the Base 8 addressing scheme.
Network address The designation used in routing to send packets to a
remote network; for example, 172.16.0.0 and 10.0.0.0.
Broadcast address Used by applications and hosts to send information
to all nodes on a network; for example, 172.16.255.255 and
10.255.255.255.
The Hierarchical IP Addressing Scheme
An IP address is made up of 32 bits of information. These are divided into
four sections, referred to as octets or bytes, containing one byte (eight bits)
each. You can depict an IP address using three methods:
Dotted-decimal, as in 172.16.30.56
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