Information Technology Reference
In-Depth Information
New network designs should be flexible and adaptable to future technologies and should
not limit the customer's options going for ward. Vo i c e over IP and video are examples of
technologies that network designs should be able to support if the customer decides to
move to a converged network. The customer should not have to undergo major hardware
and software upgrades to implement these types of technologies. Another important
consideration is the design's cost-effectiveness throughout the design and implementa-
tion stages. For example, the support and management of the network should be an im-
portant factor.
High availability is what most users want for their networked applications. The key com-
ponents of application availability are response time, throughput, and reliability. Real-time
applications such as voice and video are not very tolerant to jitter and delay.
Ta ble 6 - 3 identifies various application requirements for data, voice, and video traffic.
Ta b l e 6 - 3
Application Requirements
Key
To p i c
Data File
Transfer
Interactive
Data
Application
Real-Time Voice
Real-Time
Video
Response time
Reasonable
Within a sec-
ond
Round trip less than
250 ms with the delay
and low jitter
Minimum de-
lay and jitter
Throughput and
packet loss tolerance
High/Med
Low/Low
Low/low
High/medium
Downtime (high relia-
bility has low down-
time)
Reasonable
Low
Low
Minimum
Response Time
Response time measures the time between the client user request and the response from
the server host. The end user will accept a certain level of delay in response time and still
be satisfied. However, there is a limit to how long the user will wait. This amount of time
can be measured and serves as a basis for future application response times. Users per-
ceive the network communication in terms of how quickly the server returns the re-
quested information and how fast the screen updates. Some applications, such as a request
for an HTML web page, require shor t re s pon s e t ime s. On the other hand, a large FTP
transfer might take awhile, but this is generally acceptable.
Throughput
In network communications, throughput is the measure of data transferred from one host
to another in a given amount of time. Bandwidth-intensive applications have more of an
high-throughput applications usually involve some type of file-transfer activity. Because
