Specifications

Configuring QoS
ExtremeWare XOS 11.0 Concepts Guide 109
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, a 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 because of 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.
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 16 summarizes QoS guidelines for the different types of network traffic.
Configuring QoS
NOTE
With software version 11.0, you can create access control lists (ACLs) with QoS actions. The QoS
forwarding information you configured in an ACL takes precedence over QoS configuration using the
CLI commands. Refer to Chapter 10 for more information on ACLs.
To configure QoS, you define how your switch responds to different categories of traffic by creating and
configuring QoS profiles. You then group traffic into categories (according to the needs of the
application, as previously discussed) and assign each category to a QoS profile. Configuring QoS is a
three-step process:
Table 16: Traffic type and QoS guidelines
Traffic Type Key QoS Parameters
Voice Minimum bandwidth, priority
Video Minimum bandwidth, priority, buffering (varies)
Database Minimum bandwidth
Web browsing Minimum bandwidth for critical applications, maximum bandwidth for non-critical
applications
File server Minimum bandwidth