16.14.96/27
B
A
C
HQ
172.16.14.136/30
172.16.14.132/30
172.16.14.140/30
172.16.0.0/16
172.16.1.0/24
172.16.2.0/24
172.16.14.32/27
126 Chapter 3: Medium-Sized Routed Network Construction
creating subnets with only two hosts to be used on the WAN links. The /30 subnets
range from 172.16.14.128/30 to 172.16.14.156/30. In Figure 3-30, the WAN links
used the 172.16.14.132/30, 172.16.14.136/30, and 172.16.14.140/30 subnets out of
the range.
?– Greater capability to use route summarization: VLSM allows more hierarchical levels
within an addressing plan, allowing better route summarization within routing tables. For example,
in Figure 3-30, subnet 172.16.14.0/24 summarizes all the addresses that are further subnets of
172.16.14.0, including those from subnet 172.16.14.0/27 and from 172.16.14.128/30.
As already discussed, with VLSMs, you can subnet an already subnetted address. Consider, for
example, that you have a subnet address 172.16.32.0/20, and you need to assign addresses to a
network that has ten hosts. With this subnet address, however, you have more than 4000 (212 ??“ 2
= 4094) host addresses, most of which will be wasted. With VLSMs, you can further subnet the
address 172.
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