| Only a few years ago, TCP/IP networks
relied on simple distance-vector routing protocols and classful,
32-bit IP addressing. These technologies offered a limited capacity
for growth. Today, network designers must retool, work around, or
completely abandon these early technologies to build networks that
can handle rapid growth and constant change. This course explores
networking technologies that have evolved to meet this demand for
scalability.
In networking, scalability is the
capability to grow and adapt without major redesign or
reinstallation. Allowing for growth seems simple enough, but it can
be difficult to do without significant and costly redesign. For
example, a network may provide a small company with access to
e-mail, the Internet, and shared files. What would happen if that
company tripled in size and demanded streaming video or e-commerce?
Would the original networking media and devices adequately serve
these new applications? Organizations can ill afford to completely
re-cable and redesign their networks every time workers are moved,
new nodes are added, or new applications are introduced.
Good design is the key to a network's
capability to scale. More often than not, it is a poor design, and
not an outdated protocol or router, that prevents a network from
scaling gracefully. To be scalable, a network design should follow a
hierarchical model. This chapter discusses the components of the
hierarchical network design model and the key characteristics of
scalable internetworks.
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