ZyXEL GS-1548 User Guide - Page 157

Subnetting Example: Before Subnetting,

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Appendix A IP Addresses and Subnetting In this example, the company network address is 192.168.1.0. The first three octets of the address (192.168.1) are the network number, and the remaining octet is the host ID, allowing a maximum of 28 - 2 or 254 possible hosts. The following figure shows the company network before subnetting. Figure 90 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. GS-1524/GS-1548 User's Guide 157

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Appendix A IP Addresses and Subnetting
GS-1524/GS-1548 User’s Guide
157
In this example, the company network address is 192.168.1.0. The first three
octets of the address (192.168.1) are the network number, and the remaining
octet is the host ID, allowing a maximum of 2
8
– 2 or 254 possible hosts.
The following figure shows the company network before subnetting.
Figure 90
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.