3Com 520 - Manual (Page 66)

A-12 B R I D G I N G A N D R O U T I N G
IP Addresses
TCP/IP Numbering and subnet masking IP numbers
or addresses are normally made up of four fields
(normally called bytes ), with each byte having a
whole number value of between 0 and 255, and the
bytes separated by a full stop. For example:
123.123.123.123
An IP address is divided into two sections, one is the
Network Address section and the other is the Host
Address section. For example:
123.123.|123.123
Network Host
The divider | between the two sections is moveable
according to what class of IP address it is. The class of
address is defined by what the number is in the first
address byte:
■ For a Class A IP address the number in the first byte
will be in the range 00 to 126
■ For a Class B IP address the numbers in the first &
second bytes will be in the range 128.001 to 191.254
■ For a Class C IP address the numbers in the first,
second & third bytes will be in the range 192.000.001
to 223.255.254
For example:
Class A 1.|123.123.123
Network Host
Class B 128.001.|123.123
Network Host
Class C 192.123.123.|123
Network Host
Using of any of the address classes in a private
TCP/IP network is not a problem, providing that
connections outside of that private network to
external public or private TCP/IP networks are never
needed. If a private IP addressing number scheme is
established within a private corporate network,
connections out of that network to external public or
other private TCP/IP networks, can be achieved via a
computer which has software which enables it to
act as an IP gateway . These devices, if configured
correctly, provide the IP numbering/address
translation between the two networks.
Rc.bk : RCAPPA.FRM Page 12 Thursday, July 10, 1997 9:53 AM