SPARCbook Portable Workstation User Guide
8-5
Using the Network Interface
An Overview of TCP/IP Networking and the Internet
Note
If you do not belong to an organization with its own internal network, you may
gain access to the Internet via a modem through a local Internet Service Provider
(ISP).
Classes of Address
IP addresses consist of 32 bits and are normally written as four decimal
numbers each in the range 0-255 and separated by periods. IP addresses
have the following form:
a.b.c.d
For example, a typical IP address for a computer might be:
192.3.4.56
Any leading zeros are discarded.
The address functions in two parts: the first is used to identify a
particular network; and the second is used to identify an individual
computer, normally called a host, attached to that network. The
proportion of the address used for each function depends upon the class
of the network. There are three network classes, as summarized in Table
Class
Range
Network
Portion
Host
Portion
Likely Usage
A
1-126
a
b.c.d
Only the largest networks are assigned Class A
addresses. Each Class A network has over 16
million available addresses.
B
128-191
a.b
c.d
Large organizations and groups of subnetworks
sometimes have a Class B address. The first and
second number are assigned by the NIC, providing
over 65000 available addresses for each Class B
network.
C
192-224
a.b.c
d
Networks for the majority of companies are Class C
networks. The first three numbers are allocated by
the NIC, providing up to 254 available hosts for
each Class C network.
Table 8-1 Network Classes
S3UG4_Book Page 5 Friday, August 8, 1997 11:37 am
