ZyXEL P-871H User Guide - Page 92

Example: Four Subnets

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P-871H Series User's Guide 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 26-2 or 62 hosts for each subnet (all 0's is the subnet itself, all 1's is the broadcast address on the subnet). Table 30 Subnet 1 NETWORK NUMBER IP Address IP Address (Binary) Subnet Mask (Binary) Subnet Address: 192.168.1.0 Broadcast Address: 192.168.1.63 192.168.1. 11000000.10101000.00000001. 11111111.11111111.11111111. Lowest Host ID: 192.168.1.1 Highest Host ID: 192.168.1.62 LAST OCTET BIT VALUE 0 00000000 11000000 Table 31 Subnet 2 NETWORK NUMBER IP Address IP Address (Binary) Subnet Mask (Binary) Subnet Address: 192.168.1.64 Broadcast Address: 192.168.1.127 192.168.1. 11000000.10101000.00000001. 11111111.11111111.11111111. Lowest Host ID: 192.168.1.65 Highest Host ID: 192.168.1.126 LAST OCTET BIT VALUE 64 01000000 11000000 Table 32 Subnet 3 IP Address IP Address (Binary) Subnet Mask (Binary) Subnet Address: 192.168.1.128 Broadcast Address: 192.168.1.191 NETWORK NUMBER 192.168.1. 11000000.10101000.00000001. 11111111.11111111.11111111. Lowest Host ID: 192.168.1.129 Highest Host ID: 192.168.1.190 LAST OCTET BIT VALUE 128 10000000 11000000 IP Subnetting 91

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P-871H Series User’s Guide
IP Subnetting
91
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.
11
000000) or 255.255.255.192. Each subnet
contains 6 host ID bits, giving 2
6
-2 or 62 hosts for each subnet (all 0’s is the subnet itself, all
1’s is the broadcast address on the subnet).
Table 30
Subnet 1
NETWORK NUMBER
LAST OCTET BIT
VALUE
IP Address
192.168.1.
0
IP Address (Binary)
11000000.10101000.00000001.
00
000000
Subnet Mask (Binary)
11111111.11111111.11111111.
11
000000
Subnet Address: 192.168.1.0
Lowest Host ID: 192.168.1.1
Broadcast Address:
192.168.1.63
Highest Host ID: 192.168.1.62
Table 31
Subnet 2
NETWORK NUMBER
LAST OCTET BIT
VALUE
IP Address
192.168.1.
64
IP Address (Binary)
11000000.10101000.00000001.
01
000000
Subnet Mask (Binary)
11111111.11111111.11111111.
11
000000
Subnet Address: 192.168.1.64
Lowest Host ID: 192.168.1.65
Broadcast Address: 192.168.1.127
Highest Host ID: 192.168.1.126
Table 32
Subnet 3
NETWORK NUMBER
LAST OCTET BIT
VALUE
IP Address
192.168.1.
128
IP Address (Binary)
11000000.10101000.00000001.
10
000000
Subnet Mask (Binary)
11111111.11111111.11111111.
11
000000
Subnet Address:
192.168.1.128
Lowest Host ID: 192.168.1.129
Broadcast Address:
192.168.1.191
Highest Host ID: 192.168.1.190