Fore Systems ES-2810 - IP Address Structure; Class a Address; Class B Address; Network Numbers

FORE Systems ES-2810 Ethernet Switch User’s Manual
A - 17
Concepts in Switching
Concepts in Switching
A.6.1.3 IP Address Structure
A.6.1.3.1 Address Notation
IP addresses are 32-bit numbers. The most common notation for IP addresses divides the 32-
bit address into four 8-bit fields and specifies the value of each field as a decimal number
(from
0 to 255, each representing an 8-bit octet). Each number field is separated by a period
(for example, 14.0.65.3). This is called the dotted decimal notation.
A.6.1.3.2 Network Numbers
The 32-bit address field consists of a network and a local host part. They are divided into dif-
ferent address classes which differ in the number of bits allocated to the network part and the
host part (local address) of the address. The value of the first octet in the IP address defines the
address class (classes A, B, C, D).
A.6.1.3.3 Class A Address
The class A address comprises a 7-bit network number and a 24-bit host address. The highest
order bit is set to
0. This allows 126 class A networks.
A.6.1.3.4 Class B Address
The class B address comprises a 14-bit network number and a 16-bit host address. The two
highest-order bits are set to
1 0. This allows 16256 class B networks.
Table A.6 -
Class A Addresses
1 2 3 4
76543210765432107654321076543210
0 Network Host Address
Table A.7 -
Class B Addresses
1 2 3 4
76543210765432107654321076543210
10 Network Host Address