264 Chapter 5: Network Protocols
Step 3
Create a list, one entry above the other, that contains repeated
copies of the decimal network number. However, leave the
interesting octet blank. This will become the list of subnet
numbers.
Step 4
In the first number in the list, in the interesting octet, write a
decimal 0. This is the first (zero) subnet.
Step 5
For each successive entry in your list of subnets, add the increment
to the previous entry's interesting octet value, and record that
value in the interesting octet.
Step 6
When 256 is the value to be recorded in Step 5, you have
completed the list of subnet numbers.
Two examples of the nonbinary algorithm will be shown. First, Table 5-22 shows the familiar
150.150.0.0, mask 255.255.248.0
Table 5-22
Valid Subnet Numbers, 150.150.0.0, Mask 255.255.248.0
Step 1
Interesting byte is 3
Step 2
Increment 2
3
=
8
Step 3
150.150.____.0
150.150.____.0
150.150.____.0
150.150.____.0
150.150.____.0 and so forth
Step 4
150.150.0.0
Step 5
150.150.8.0
150.150.16.0
150.150.24.0
Skipped a few for brevity
150.150.248.0 (This is the last one)
Step 6
150.150.256.0 (This one is invalid)
ch05.fm Page 264 Monday, March 20, 2000 5:06 PM