Although every large internetwork has
unique features, all scalable networks have essential attributes in
common. A scalable network has five key characteristics:
- Reliable and available - A
reliable network should be dependable and available 24 hours a
day, 7 days a week. In addition, failures need to be isolated,
and recovery must be invisible to the end user.
- Responsive - A responsive
network should provide Quality of Service (QoS) for various
applications and protocols without affecting a response at the
desktop. For example, the internetwork must be capable of
responding to latency issues common for Systems Network
Architecture (SNA) traffic but still allow for the routing of
desktop traffic, such as Internetwork Packet Exchange (IPX),
without compromising QoS requirements.
- Efficient - Large
internetworks must optimize the use of resources, especially
bandwidth. Reducing the amount of overhead traffic, such as
unnecessary broadcasts, service location, and routing updates,
results in an increase in data throughput without increasing the
cost of hardware or the need for additional WAN services.
- Adaptable - An adaptable
network is capable of accommodating disparate protocols,
applications, and hardware technologies.
- Accessible but secure - An
accessible network allows for connections using dedicated,
dialup, and switched services while maintaining network
integrity.
The Cisco IOS offers a rich set of
features that support network scalability. The remainder of this
chapter outlines specific IOS features that work to promote these
five key characteristics of a scalable network.
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