Zoom ZoomAir AP11, Installation Manual

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70 Installation Guide: Z
OOM
A
IR
AP11
machines each. (There are 30 host addresses available instead of 32
because the top and bottom addresses are reserved for broadcasting
within the subnet.)
Step 2 is to calculate the subnet mask. Since we are allocating the 3
leftmost bits of the final byte for subnet information, Acme’s subnet
mask becomes 1111111.11111111.11111111.11100000 in binary
notation.
To translate this binary number to a decimal number, consult the table
below.
Bit No. 8 7 6 5 4 3 2 1
Binary
Value 1 1 1 0 0 0 0 0
Decimal
Value 128 64 32 16 8 4 2 1
Adding the decimal values of the bits with a 1 in them (128+64+32)
equals 224. The netmask is then 255.255.255.224.
Step 3 is to calculate the legal subnet numbers for Acme’s five
networks. All the subnets begin with 192.168.1, and the first three bits
of the final byte have been dedicated to subnet information. These
three bits gives us eight possible numbers: 000, 001, 010, 011, 100,
101, 110, and 111. Because 000 and 111 are reserved for broadcasting,
we have six usable subnets: 001, 010, 011, 100, 101, and 110. The last
five bits, reserved for host address information, are always zeros.
Acme’s six subnets written in binary and decimal form are listed
below:
Binary Decimal
00100000 32
01000000 64
01100000 96
10000000 128
10100000 160
11000000 192
The last step is to determine which host numbers are legal. Although
we have reserved five bits for host information (00000 to 11111 in
binary notation), 00000 and 11111 are reserved for broadcasting; so