Requirements of the Scalable Internetwork
It must be responsive. Because network growth often occurs on a daily
basis, the administrator's duty to maintain the network's responsiveness
can become overwhelming. The Cisco IOS provides solutions to provide
Quality of Service (QoS) that will allow multiple protocols to be sup-
ported on the network, without compromising QoS requirements.
It must be efficient. Efficiency, in a nutshell, means keeping the band-
width from becoming saturated. A central goal of this book is to arm you
with information on fine-tuning your router to optimize the existing
bandwidth on your internetwork. You'll learn how to achieve that objec-
tive through innovative techniques such as using access lists, optimizing
route update operations, and scaling IP addresses.
It must be adaptable. The internetwork must be designed to respond
masterfully to change and to accommodate disparate networks as well as
older legacy technologies.
It must be easily accessible while being secure. It is a network adminis-
trator's foremost obligation (obsession?) to meet business requirements
by ensuring that network resources remain available to users at all times,
while managing to keep out any and all hackers. The Cisco IOS provides
dedicated and switched WAN support such as Frame Relay, SMDS, X.25,
and ATM to equip networking professionals with options to meet cost,
location, security, and traffic requirements. The Cisco IOS also provides
exterior routing support with the Exterior Gateway Protocol (EGP) and
Border Gateway Protocol (BGP) to permit routing on the Internet with
We will talk about each of these requirements in the following sections.
Reliability and Availability
Because a network is depended upon so heavily--ideally, it's up and running
24 hours a day, 365 days a year--failures and downtime must be kept to a
minimum. It's also vital that when a failure does occur, it's easy to isolate,
reducing the time needed for troubleshooting. When it comes to reliability,
the internetwork's Core layer is the most critical. Cisco's definition of reli-
able is an internetwork that can respond quickly to changes in the network
topology and accommodate failures by rerouting traffic.
Copyright ©2001 SYBEX , Inc., Alameda, CA