ZyXEL Communications Prestige 662HW Series User Manual page 404

Prestige 662HW Series User's Guide
Subnet Mask (Binary)
Subnet Address: 192.168.1.128
Broadcast Address: 192.168.1.255
The remaining 7 bits determine the number of hosts each subnet can have. Host IDs of all zeros
represent the subnet itself and host IDs of all ones are the broadcast address for that subnet, so the
actual number of hosts available on each subnet in the example above is 2
subnet.
192.168.1.0 with mask 255.255.255.128 is the subnet itself, and 192.168.1.127 with mask
255.255.255.128 is the directed broadcast address for the first subnet. Therefore, the lowest IP address
that can be assigned to an actual host for the first subnet is 192.168.1.1 and the highest is
192.168.1.126. Similarly the host ID range for the second subnet is 192.168.1.129 to 192.168.1.254.
Example: Four Subnets
The above example illustrated using a 25-bit subnet mask to divide a class "C" address space into two
subnets. Similarly to divide a class "C" address into four subnets, you need to "borrow" two host ID
bits to give four possible combinations of 00, 01, 10 and 11. The subnet mask is 26 bits
(11111111.11111111.11111111.11000000) or 255.255.255.192. Each subnet contains 6 host ID bits,
6
giving 2 -2 or 62 hosts for each subnet (all 0's is the subnet itself, all 1's is the broadcast address on
the subnet).
IP Address
IP Address (Binary)
Subnet Mask (Binary)
Subnet Address: 192.168.1.0
Broadcast Address: 192.168.1.63
IP Address
IP Address (Binary)
Subnet Mask (Binary)
Subnet Address: 192.168.1.64
Broadcast Address: 192.168.1.127
IP Address
B-4
Chart B-6 Subnet 2
NETWORK NUMBER
11111111.11111111.11111111.
Lowest Host ID: 192.168.1.129
Highest Host ID: 192.168.1.254
Chart B-7 Subnet 1
NETWORK NUMBER
192.168.1.
11000000.10101000.00000001.
11111111.11111111.11111111.
Lowest Host ID: 192.168.1.1
Highest Host ID: 192.168.1.62
Chart B-8 Subnet 2
NETWORK NUMBER
192.168.1.
11000000.10101000.00000001.
11111111.11111111.11111111.
Lowest Host ID: 192.168.1.65
Highest Host ID: 192.168.1.126
Chart B-9 Subnet 3
NETWORK NUMBER
192.168.1.
LAST OCTET BIT VALUE
10000000
7
– 2 or 126 hosts for each
LAST OCTET BIT VALUE
0
00000000
11000000
LAST OCTET BIT VALUE
64
01000000
11000000
LAST OCTET BIT VALUE
128
IP Subnetting