Applications and Types of QoS
ExtremeWare XOS 10.1 Concepts Guide
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Video Applications
Video applications are similar in needs to voice applications, with the exception that bandwidth
requirements are somewhat larger, depending on the encoding. It is important to understand the
behavior of the video application being used. For example, in the playback of stored video streams,
some applications can 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 present a
problem to 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). Key QoS
parameters for video applications include minimum bandwidth and priority.
Critical Database Applications
Database applications, such as those associated with ERP, typically do not demand significant
bandwidth and are tolerant of delay. You can establish a minimum bandwidth using a priority less than
that of delay-sensitive applications.
Web Browsing Applications
QoS needs for Web browsing applications cannot 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. Traffic groupings can typically be distinguished from each other by their server source and
destinations. Most browser-based applications are distinguished by the dataflow being asymmetric
(small dataflows from the browser client, large dataflows from the server to the browser client).
An exception to this may be created by some Java
™
-based applications. In addition, Web-based
applications are generally tolerant of latency, jitter, and some packet loss, however small packet-loss
may have a large impact on perceived performance due to the nature of TCP. The relevant parameter
for protecting browser applications is minimum bandwidth. The relevant parameter for preventing
non-critical browser applications from overwhelming the network is maximum bandwidth. In addition,
RED can be used to reduce session loss if the queue that floods Web traffic becomes over-subscribed.
File Server Applications
With some dependencies on the network operating system, file serving typically poses the greatest
demand on bandwidth, although file server applications are very tolerant of latency, jitter, and some
packet loss, depending on the network operating system and the use of TCP or UDP.
NOTE
Full-duplex links should be used when deploying policy-based QoS. Half-duplex operation on links can
make delivery of guaranteed minimum bandwidth impossible.
Table 11 summarizes QoS guidelines for the different types of network traffic.
Table 11: Traffic Type and QoS Guidelines
Traffic Type
Key QoS Parameters
Voice
Minimum bandwidth, priority
Video
Minimum bandwidth, priority, buffering (varies)
Database
Minimum bandwidth
Summary of Contents for ExtremeWare XOS 10.1
Page 12: ...12 ExtremeWare XOS 10 1 Concepts Guide Contents...
Page 15: ...Part 1 Using ExtremeWare XOS...
Page 16: ......
Page 20: ...20 ExtremeWare XOS 10 1 Concepts Guide ExtremeWare XOS Overview...
Page 32: ...32 ExtremeWare XOS 10 1 Concepts Guide Accessing the Switch...
Page 74: ...74 ExtremeWare XOS 10 1 Concepts Guide Virtual LANs VLANs...
Page 80: ...80 ExtremeWare XOS 10 1 Concepts Guide Forwarding Database FDB...
Page 112: ...112 ExtremeWare XOS 10 1 Concepts Guide Status Monitoring and Statistics...
Page 133: ...Part 2 Using Switching and Routing Protocols...
Page 134: ......
Page 174: ...174 ExtremeWare XOS 10 1 Concepts Guide Virtual Router Redundancy Protocol...
Page 184: ...184 ExtremeWare XOS 10 1 Concepts Guide IP Unicast Routing...
Page 202: ...202 ExtremeWare XOS 10 1 Concepts Guide Interior Gateway Protocols...
Page 216: ...216 ExtremeWare XOS 10 1 Concepts Guide Exterior Gateway Routing Protocols...
Page 224: ...224 ExtremeWare XOS 10 1 Concepts Guide IP Multicast Routing...
Page 225: ...Part 3 Appendixes...
Page 226: ......
Page 234: ...234 ExtremeWare XOS 10 1 Concepts Guide Software Upgrade and Boot Options...
Page 242: ...242 ExtremeWare XOS 10 1 Concepts Guide Troubleshooting...
Page 256: ...4 ExtremeWare XOS 10 1 Concepts Guide Index of Commands...