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12 Chapter 1: Design Overview
Assess Costs and Risks
There is a natural trade-off between cost and availability. A good design can create availability
but can cost extra money. Over time, internetwork support is the most significant cost
component in an internetwork. The next-biggest costs are the wide-area network links. An ideal
assessment of the risks involved should result in a cost-effective network. When you assess the
risks, the network's benefits must be greater than the costs.
Implement and Monitor
Implement the design in phased increments. If possible, test the design in a lab environment
before rollout. As the design is implemented, verify and validate each phase of the rollout. After
implementing, monitor the network.
Monitoring is listed as the last phase, but it can also be viewed as the first phase in managing
the network's ongoing changes. In the context of this step, consider the following actions:
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Using network management tools for monitoring
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Performing proactive data gathering
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Knowing when to scale the network to meet new demands
-- Upgrading hardware
-- Adding faster circuit speeds
Use network management tools and protocol analyzers to maintain a snapshot of the network.
Monitor traffic patterns at determined intervals. One thing is certain: Change is inevitable.
Network applications will continue to demand more bandwidth. It is essential that the CCDP
measure the network under normal conditions to determine how to plan for changes in network
capacity. You should monitor the network for growth before the network slows to a crawl.
Network management applications that use Simple Network Management Protocol (SNMP)
provide a useful array of tools to control internetwork support costs:
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Cisco debug and show commands
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Syslog
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Protocol analyzers
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DNS
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TFTP and FTP
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DHCP and BOOTP
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Telnet
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TACACS
87200333.book Page 12 Wednesday, August 22, 2001 2:18 PM