When designing a WAN, you need to start
by gathering data about the business structure and processes. Next, you need to determine who the most important people will be in helping you design the network.
You need to speak to major users and find out their geographic location, their current applications, and their projected needs. The final network design should reflect the user
requirements.
In general, users primarily want
application availability in their networks. The chief components of
application availability are response time, throughput, and
reliability:
- Response time is the time between
entry of a command or keystroke and the host system's execution of
the command or delivery of a response. Applications in which fast
response time is considered critical include interactive online
services, such as automated tellers and point-of-sale machines.
- Throughput-intensive applications
generally involve file-transfer activities. However,
throughput-intensive applications also usually have low
response-time requirements. Indeed, they can often be scheduled at
times when response-time-sensitive traffic is low (for example,
after normal work hours).
- Although reliability is always
important, some applications have genuine requirements that exceed
typical needs. Organizations that conduct all business activities online or over the telephone require nearly 100% uptime.
Financial
services, securities exchanges, and emergency, police, and
military operations are a few examples. These situations require a high level of hardware and redundancy.
Determining the cost of downtime is essential in determining the importance of reliability to your network.
You can assess user requirements in a
number of ways. The more involved your users are in the process, the
more likely your evaluation will be accurate. In general, you can use
the following methods to obtain this information:
- User community profiles-Outline what
different user groups require. This is the first step in
determining network requirements. Although most general users have the same requirements of e-mail, they may also have different needs such as sharing local print servers in their area.
- Interviews, focus groups, and surveys build a baseline for implementing a network. Understand that some groups might require access to common servers. Others might want to allow external access to specific internal computing resources. Certain organizations might require IS support systems to be managed in a particular way, according to some external standard.
- The least formal method of obtaining
information is to conduct interviews with key user groups. Focus
groups can also be used to gather information and generate
discussion among different organizations with similar (or
dissimilar) interests. Finally, formal surveys can be used to get
a statistically valid reading of user sentiment regarding a
particular service level.
- Human factors tests-The most
expensive, time-consuming, and possibly revealing method of
assessing user requirements is to conduct a test involving
representative users in a lab environment. This is most applicable
when you're evaluating response time requirements. For example,
you might set up working systems and have users perform normal
remote host activities from the lab network. By evaluating user
reactions to variations in host responsiveness, you can create
benchmark thresholds for acceptable performance.
After gathering data about the
corporate structure, you need to determine where information flows in
the company. Find out where shared data resides and who uses it.
Determine whether data outside the company is accessed.
Make sure you understand the
performance issues of any existing network. If time permits, analyze
the performance of the existing network.
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Washington
Project: Understanding the Customer
First and foremost, you must understand your
customers; in the case of the Washington School
District, your customers include teachers,
students, staff members, and administrators.
You need to determine whether the district has
documented policies in place. You need to answer
questions like the following:
- Has district data been declared mission
critical?
- Have district operations been declared
mission critical?
- What protocols are allowed on the district
network?
- Are only certain desktop hosts supported in
the district?
Mission-critical data and operations are
considered key to the business, and access to them
is critical to the business running on a daily
basis. You need to determine who in the district
has authority over mission-critical data and
operations, along with addressing, naming,
topology design, and configuration. Some districts
have a central Management Information System (MIS)
department that controls everything. Some
districts have very small MIS departments and,
therefore, must pass on authority to other
departments and local school sites.
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