ZyXEL WAP3205 v2 User Guide - Page 144

Example: Four Subnets, Subnetting Example: After Subnetting

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Appendix B IP Addresses and Subnetting The following figure shows the company network after subnetting. There are now two sub-networks, A and B. Figure 89 Subnetting Example: After Subnetting In a 25-bit subnet the host ID has 7 bits, so each sub-network has a maximum of 27 - 2 or 126 possible hosts (a host ID of all zeroes is the subnet's address itself, all ones is the subnet's broadcast address). 192.168.1.0 with mask 255.255.255.128 is subnet A itself, and 192.168.1.127 with mask 255.255.255.128 is its broadcast address. Therefore, the lowest IP address that can be assigned to an actual host for subnet A is 192.168.1.1 and the highest is 192.168.1.126. Similarly, the host ID range for subnet B is 192.168.1.129 to 192.168.1.254. Example: Four Subnets The previous example illustrated using a 25-bit subnet mask to divide a 24-bit address into two subnets. Similarly, to divide a 24-bit address into four subnets, you need to "borrow" two host ID bits to give four possible combinations (00, 01, 10 and 11). The subnet mask is 26 bits (11111111.11111111.11111111.11000000) or 255.255.255.192. 144 WAP3205 User's Guide

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Appendix B IP Addresses and Subnetting
WAP3205 User’s Guide
144
The following figure shows the company network after subnetting. There are now
two sub-networks,
A
and
B
.
Figure 89
Subnetting Example: After Subnetting
In a 25-bit subnet the host ID has 7 bits, so each sub-network has a maximum of
2
7
– 2 or 126 possible hosts (a host ID of all zeroes is the subnet’s address itself,
all ones is the subnet’s broadcast address).
192.168.1.0 with mask 255.255.255.128 is subnet
A
itself, and 192.168.1.127
with mask 255.255.255.128 is its broadcast address. Therefore, the lowest IP
address that can be assigned to an actual host for subnet
A
is 192.168.1.1 and
the highest is 192.168.1.126.
Similarly, the host ID range for subnet
B
is 192.168.1.129 to 192.168.1.254.
Example: Four Subnets
The previous example illustrated using a 25-bit subnet mask to divide a 24-bit
address into two subnets. Similarly, to divide a 24-bit address into four subnets,
you need to “borrow” two host ID bits to give four possible combinations (00, 01,
10 and 11). The subnet mask is 26 bits
(11111111.11111111.11111111.
11
000000) or 255.255.255.192.