Installing and Administering LAN/9000 Software

Chapter 6 143
Network Addressing
Subnet Addresses
Figure 6-6 Subnet Address and Subnet Number of Class C Internet Address
192.6.12.33
The following rules apply when choosing a subnet addressing scheme
and an internet address:
• All subnets on the same network must have the same network
address.
• If your system is attached to more than one physical network, the
subnet addresses of the interfaces on your system cannot be the same.
• Do not assign a host address where all the bits of the host number are
0 or all the bits are 1.
You may choose a fixed-length subnet addressing scheme in which one
subnet mask will be used in all subnets in your network. You may also
choose a variable-length subnet addressing scheme in which the subnet
masks may be varied depending on the size of the subnets you want.
If you wish to implement variable-length subnetting, first read the
conceptual information, “Assigning Variable-Length Subnet Addresses”
later in this chapter. Then refer to the specific task-oriented instructions
in the “Manually Installing and Configuring LAN/9000” chapter earlier
in this manual. For additional information, refer to the following online
man pages: ifconfig(1M), netstat(1), ppl.remotes(4), routing(7),
and route(1M). Detailed descriptionsof fixed-length and variable-length
subnet addressing follow.
Fixed-Length Subnet Addressing
This section shows you how to apply a fixed-length subnet addressing
scheme on a class C network. The same steps may be applied on a Class
11 00000 01100 00011000010000000 001
192 . 6 . 12 . 33
Class C
IP Address:
network address = 192.6.12 subnet number = 1
host address = 33
subnet address = 192.6.12.32