User's Manual

SPEEDLAN 4100 & 4200 Installation and Operation User Guide
Setting Up the IP Addresses (IP Host Setup) 7-5
Subnetting a Network
The increasing number of hosts and networks make impractical address blocks that are not smaller
than 245. In order keep the IP address small, so routers can manage them without changing the
whole protocol, a smaller network definition is created. This is called a subnet. Subnets are intended
to:
• Reduce network traffic
• Optimize performance
• Simplify management
• Create more effective and efficient addresses for large geographic distances
Default Subnet masks
• Class A: 255.0.0.0
• Class B: 255.255.0.0
• Class C: 255.255.255.0
Note: Subnet mask is bolded.
What is a Subnet?
Subnetting allows you to create multiple networks within one Class A, B, or C network. Each data
link (octet) contains its own unique identifier also known as the subnet. Also, each node on the same
data link must belong on the same subnet as well.
What is a Subnet Mask?
A subnet mask allows you to mask section(s) (depending on the class specified) of the octets in the
network address. Each octet used in the subnet mask is assigned to a data link. The leftover octet(s)
are assigned to the remaining nodes.
For more information on subnetting, see the example below and Diagram of Subnetting a Network,
page 7-7.