| A critical prerequisite to building a
scalable network is having an efficient address architecture adhered
to by all users of that network. Address architectures can take many
different forms. Network addresses are always numeric, but they can
be expressed in base 2 (binary), base 10 (decimal), or even base 16
(hexadecimal) number systems. They can be proprietary or open for
all to see and implement. Address architectures can be highly
scalable or intentionally designed to serve just small communities
of users.
This chapter examines the address
architecture implemented by the Internet Protocol (IP). As IP has
evolved substantially over the past 20 years, so has its address
architecture. This chapter describes the evolution of the IP address
architecture and explains critical key components related to IP
addressing, including subnetworks, subnetwork addresses or masks,
classless interdomain routing (CIDR), variable-length subnet masking
(VLSM) and route summarization
The content in this chapter is a
prerequisite to understanding how to reduce routing table entries
and the amount of route updates issued by routing protocols, such as
OSPF (Open Shortest Path First). Knowing these IP addressing
techniques enables you to define an appropriate IP address scheme
for your network.
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