Intel 480T User Manual page 134

C H A P T E R 8
132
Quality of Service (QoS)
sensitivity to latency and jitter, and sensitivity and impact of packet
loss.
Voice Applications
Voice applications typically demand small amounts of bandwidth,
but the bandwidth needs to be constant and predictable. As such,
voice applications are typically sensitive to latency (inter-packet
delay) and jitter (variation in inter-packet delay). The most
important QoS profile parameter to establish for voice applications
is minimum bandwidth, followed by priority.
Video Applications
Video applications are typically similar in their needs to voice
applications, with the exception that bandwidth needs are somewhat
larger, depending on the encoding. It is important to understand the
behavior of the video application being used. In the playback of
stored video streams, some applications may transmit large
amounts of data for multiple streams in one "spike," with the
expectation that the end-stations will buffer significant amounts of
video-stream data. This can pose an issue with the network
infrastructure, because it must be capable of buffering the
transmitted spikes where there are speed differences (for example,
going from Gigabit Ethernet to Fast Ethernet). The relevant
parameters for video applications are minimum bandwidth, priority,
and possibly buffering (depending upon the behavior of the
application).
Critical Database Applications
Database applications, such as those associated with ERP, typically
do not demand significant bandwidth and are tolerant of delay.
Establishing a minimum bandwidth using a priority less than that of
delay-sensitive applications satisfies these needs.
Web Browsing Applications
The desired QoS applications for Web browsing cannot typically be
generalized into a single category. For example, ERP applications
that use a browser front-end may be more important than retrieving
daily news information. These traffic groupings can typically be
distinguished from each other by their server source and