B
IP
A
N
D
IPX A
D
D
R
E
S
S
E
S
IP Addresses
A world-wide network such as the Internet needs a
globally-accepted method of identifying individual
devices (workstations and network equipment).
Devices on the Internet are assigned unique
addresses. The Internet then behaves like a virtual
network, using these assigned addresses when
sending or receiving packets.
Internet addressing uses a 32-bit (or 4 octet) address
field. The bits that make up an Internet address are
divided into two parts:
■
The first part identifies the network on which the
device resides.
■
The second part identifies the device itself.
Devices attached to the same network must have the
same number assigned to the network portion of the
address, but have different numbers assigned to the
device portion of the address.
To ensure the uniqueness of Internet addresses, they
are assigned by three organizations, NIC, RIPE and
APNIC-DOM. These organizations assign a globally
unique network number to each network that wants
to connect to the Internet. They only assign the
network portion of the address; assigning the device
numbers is your responsibility.
If you do not plan to connect to the Internet but
need to use IP addresses on your network, you could
assign network numbers on your own. However, NIC,
RIPE and APNIC-DOM still assign and register unique
network numbers to organizations not planning to
join the Internet. This means that if you change your
mind later, you can simply connect to the Internet
without having to obtain new network numbers and
reconfigure every device on your network with a
new address.
For information on assigning your own IP addresses
for a small, contained network, see
“Assigning IP
Addresses to a Small, Contained Network” on
page B-5
.
16710.bk : IPADDRES.FRM Page 1 Tuesday, October 7, 1997 11:38 AM
