Extreme Networks Altitude 4000 Series, Справочное руководство, Страница: 264 / 521

Chapter 7: Wireless Configuration
Altitude
TM
4000 Series Access Point System Reference Guide
264
14 Set the following Accelerated Multicast settings:
15 Select OK when completed to update this WLAN’s Multimedia Optimizations settings. Select Reset to
revert back to the last saved configuration.
Radio QoS Policy
Without a dedicated QoS policy, a network operates on a best-effort delivery basis, meaning all traffic
has equal priority and an equal chance of being delivered in a timely manner. When congestion occurs,
all traffic has an equal chance of being dropped!
When configuring a QoS policy for a radio, select specific network traffic, prioritize it, and use
congestion-management and congestion-avoidance techniques to provide deployment cusomizations
best suited to each QoS policy’s intended wireless client base.
Extreme Networks Access Point radios and wireless clients support several Quality of Service (QoS)
techniques enabling real-time applications (such as voice and video) to co-exist simultaneously with
lower priority background applications (such as Web, Email and file transfers). A well designed QoS
policy should:
●
Classify and mark data traffic to accurately prioritize and segregate it (by access category)
throughout the network.
●
Minimize the network delay and jitter for latency sensitive traffic.
●
Ensure high priority traffic has a better likelihood of delivery in the event of network congestion.
●
Prevent the ineffective utilization of access points degrading session quality by configuring
admission control mechanisms within each radio QoS policy
Within a Extreme Networks wireless network, wireless clients supporting low and high priority traffic
contend with one another for data resources. The IEEE 802.11e amendment has defined
Enhanced
Distributed Channel Access (EDCA) mechanisms stating high priority traffic can access the network
sooner then lower priority traffic. The EDCA defines four traffic classes (or access categories); voice
(highest), video (next highest), best effort and background (lowest).The EDCA has defined a time
interval for each traffic class, known as the
Transmit Opportunity (TXOP). The TXOP prevents traffic of a
higher priority from completely dominating the wireless medium, thus ensuring lower priority traffic is
still supported by connected radios.
IEEE 802.11e includes an advanced power saving technique called Unscheduled Automatic Power Save
Delivery (U-APSD) that provides a mechanism for wireless clients to retrieve packets buffered by an
Disable Multicast
Streaming Select this option to disable all Multicast Streaming on the WLAN. This
option is enabled by default.
Automatically Detect
Multicast Streams Select this option to allow an administrator to have multicast packets that
are being bridged converted to unicast to provide better overall airtime
utilization and performance. The administrator can either have the
system automatically detect multicast streams and convert all detected
multicast streams to unicast, or specify which multicast streams are
converted to unicast. When the stream is converted and being queued
up for transmission, there are a number of classification mechanisms that
can be applied to the stream, and the administrator can select what type
of classification they would want.
Manually Configure
Multicast Addresses Select this option and specify a list of multicast addresses and
classifications. Packets are accelerated when the destination addresses
matches.