Example: Four Subnets - Nortel BCM50e Configuration

238 Appendix G IP subnetting
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, giving 2
itself, all 1s is the broadcast address on the subnet).
Table 54 Subnet 1
IP Address
IP Address (Binary)
Subnet Mask (Binary)
Subnet Address: 192.168.1.0
Broadcast Address: 192.168.1.63 Highest Host ID: 192.168.1.62
Table 55 Subnet 2
IP Address
IP Address (Binary)
Subnet Mask (Binary)
Subnet Address: 192.168.1.64
Broadcast Address:
192.168.1.127
N0115789
-2 or 62 hosts for each subnet (all 0s is the subnet
6
Network number
192.168.1.
11000000.10101000.00000001.
11111111.11111111.11111111.
Lowest Host ID: 192.168.1.1
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
Last octet bit value
0
00000000
11000000
Last octet bit value
64
01000000
11000000