100
Chapter 3
IP Addressing
After picking the first available network number (172.16.0.4) given our
30-bit subnet mask and eliminating host IP addresses that are all ones and all
zeros, we have the following range of numbers: 172.16.0.5­172.16.0.6.
Each of these numbers in the range can be assigned to one side of the serial link.
Next, as shown in the following table, we will calculate the range of IP
addresses to use for our server farm segment, which needs 50 IP addresses.
We pick the first available network address, given our 26-bit subnet mask.
In this case, the first available network is 172.16.0.64.
Eliminating host IP addresses that contain all ones and all zeros, as before,
we discover that our IP address range for this segment is: 172.16.0.65­
172.16.0.126.
We now perform the same steps for the Ethernet user segment, as shown
in the table below:
3rd Octet
4th Octet
Decimal IP Address
128 64 32 16 8 4 2 1
128 64 32 16 8 4 2 1
(Last 16 bits in bold)
Subnet mask
1 1 1 1 1 1 1 1
1 1 0 0 0 0 0 0
255.255.255.248
Network
0 0 0 0 0 0 0 0
0 1 0 0 0 0 0 0
172.16.0.64
First IP in
range
0 0 0 0 0 0 0 0
0 1 0 0 0 0 0 1
172.16.0.65
Last IP in
range
0 0 0 0 0 0 0 0
0 1 1 1 1 1 1 0
172.16.0.126
3rd Octet
4th Octet
Decimal IP Address
128 64 32 16 8 4 2 1
128 64 32 16 8 4 2 1
(Last 16 bits in bold)
Subnet mask
1 1 1 1 1 1 1 1
0 0 0 0 0 0 0 0
255.255.255.0
Network
0 0 0 0 0 0 0 1
0 0 0 0 0 0 0 0
172.16.1.0
First IP in
range
0 0 0 0 0 0 0 1
0 0 0 0 0 0 0 1
172.16.1.1
Last IP in
range
0 0 0 0 0 0 0 1
1 1 1 1 1 1 1 0
172.16.1.254
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