Table of Contents
Advertisement
B-4 IP Subnetting
The first mask shown is the class "C" natural mask. Normally if no mask is
specified it is understood that the natural mask is being used.
Example: Two Subnets
As an example, you have a class "C" address 192.168.1.0 with subnet mask of
255.255.255.0.
IP Address
IP Address (Binary)
Subnet Mask
Subnet Mask (Binary)
The first three octets of the address make up the network number (class "C"). You
want to have two separate networks.
Divide the network 192.168.1.0 into two separate subnets by converting one of the
host ID bits of the IP address to a network number bit. The "borrowed" host ID bit
can be either "0" or "1" thus giving two subnets; 192.168.1.0 with mask
255.255.255.128 and 192.168.1.128 with mask 255.255.255.128.
In the following charts, shaded/bolded last octet bit values indicate host ID bits
"borrowed" to form network ID bits. The number of "borrowed" host ID bits
determines the number of subnets you can have. The remaining number of host ID
bits (after "borrowing") determines the number of hosts you can have on each
subnet.
Chart B-5 Subnet 1
IP Address
IP Address (Binary)
Subnet Mask
Subnet Mask (Binary)
Subnet Address: 192.168.1.0
Broadcast Address: 192.168.1.127
317516-A Rev 00
NETWORK NUMBER
192.168.1.
11000000.10101000.00000001.
255.255.255.
11111111.11111111.11111111.
NETWORK NUMBER
192.168.1.
11000000.10101000.00000001.
255.255.255.
11111111.11111111.11111111.
Lowest Host ID: 192.168.1.1
Highest Host ID: 192.168.1.126
HOST ID
0
00000000
0
00000000
LAST OCTET BIT VALUE
0
00000000
128
10000000
Advertisement
Table of Contents
