ZyXEL Communications wap3205 V3 - Page 91

Appendix A IP Addresses and Subnetting
WAP3205 v3 User’s Guide
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Figure 68 Subnetting Example: Before Subnetting
You can “borrow” one of the host ID bits to divide the network 192.168.1.0 into two separate sub-
networks. The subnet mask is now 25 bits (255.255.255.128 or /25).
The “borrowed” host ID bit can have a value of either 0 or 1, allowing two subnets; 192.168.1.0 /25 and
192.168.1.128 /25.
The following figure shows the company network after subnetting. There are now two sub-networks, A
and B.
Figure 69 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).