User's Manual
Table Of Contents
- Warranty and Product Registration
- How to Use This Guide
- Contents
- Figures
- Tables
- Getting Started
- Web Configuration
- Command Line Interface
- Using the Command Line Interface
- General Commands
- System Management Commands
- country
- prompt
- system name
- system-resource
- password
- reboot-schedule
- apmgmgtui ssh enable
- apmgmtui ssh port
- apmgmtui telnet- server enable
- apmgmtui http port
- apmgmtui http server
- apmgmtui http session-timeout
- apmgmtui https port
- apmgmtui https server
- apmgmtui snmp
- apmgmtip
- show apmanagement
- show system
- show system resource
- show version
- show config
- System Logging Commands
- System Clock Commands
- DHCP Relay Commands
- SNMP Commands
- snmp-server community
- snmp-server contact
- snmp-server location
- snmp-server enable server
- snmp-server host
- snmp-server trap
- snmp-server vacm view
- snmp-server vacm group
- snmp-server user
- snmp-server target
- snmp-server filter
- show snmp users
- show snmp target
- show snmp filter
- show snmp
- show snmp vacm view
- show snmp vacm group
- Flash/File Commands
- RADIUS Client Commands
- 802.1X Authentication Commands
- MAC Address Authentication Commands
- Filtering Commands
- Spanning Tree Commands
- bridge stp service
- bridge stp br-conf forwarding-delay
- bridge stp br-conf hello-time
- bridge stp br-conf max-age
- bridge stp br-conf priority
- bridge stp port-conf interface
- bridge-link path-cost
- bridge-link port- priority
- vap (STP Interface)
- path-cost (STP Interface)
- port-priority (STP Interface)
- bridge mac-aging
- show bridge stp
- show bridge br-conf
- show bridge port-conf interface
- show bridge status
- show bridge forward address
- show bridge mac- aging
- WDS Bridge Commands
- Ethernet Interface Commands
- Wireless Interface Commands
- interface wireless
- vap
- a-mpdu
- a-msdu
- channel
- transmit-power
- min-allowed-rate
- disable-coexist
- make-rf-setting- effective
- preamble
- short-guard-interval
- beacon-interval
- dtim-period
- rts-threshold
- ssid
- closed-system
- max-client
- max-association
- client-assoc-preempt
- assoc-timeout- interval
- auth-timeout-interval
- multicast-enhance
- shutdown (VAP)
- interfere-chan- recover
- antenna-chain
- long-distance
- long-distance reference-data
- long-distance slottime
- long-distance acktimeout
- long-distance ctstimeout
- bandwidth-control downlink
- bandwidth-control downlink rate
- bandwidth-control uplink
- bandwidth-control uplink rate
- show interface wireless
- show station
- show station statistics
- Wireless Security Commands
- Rogue AP Detection Commands
- Link Integrity Commands
- Link Layer Discovery Commands
- VLAN Commands
- WMM Commands
- QoS Commands
- Appendices
- Index of CLI Commands
- Index
Chapter 6
| Wireless Settings
Wi-Fi Multimedia (WMM)
– 87 –
WMM Operation — WMM uses traffic priority based on the four ACs; Voice, Video,
Best Effort, and Background. The higher the AC priority, the higher the probability
that data is transmitted.
When the access point forwards traffic, WMM adds data packets to four
independent transmit queues, one for each AC, depending on the 802.1D priority
tag of the packet. Data packets without a priority tag are always added to the Best
Effort AC queue. From the four queues, an internal “virtual” collision resolution
mechanism first selects data with the highest priority to be granted a transmit
opportunity. Then the same collision resolution mechanism is used externally to
determine which device has access to the wireless medium.
For each AC queue, the collision resolution mechanism is dependent on two timing
parameters:
◆ AIFSN (Arbitration Inter-Frame Space Number), a number used to calculate the
minimum time between data frames
◆ CW (Contention Window), a number used to calculate a random backoff time
After a collision detection, a backoff wait time is calculated. The total wait time is
the sum of a minimum wait time (Arbitration Inter-Frame Space, or AIFS)
determined from the AIFSN, and a random backoff time calculated from a value
selected from zero to the CW. The CW value varies within a configurable range. It
starts at CWMin and doubles after every collision up to a maximum value, CWMax.
After a successful transmission, the CW value is reset to its CWMin value.
Table 2: WMM Access Categories
Access
Category
WMM
Designation
Description 802.1D
Tags
AC_VO (AC3) Voice Highest priority, minimum delay. Time-sensitive
data such as VoIP (Voice over IP) calls.
7, 6
AC_VI (AC2) Video High priority, minimum delay. Time-sensitive data
such as streaming video.
5, 4
AC_BE (AC0) Best Effort Normal priority, medium delay and throughput.
Data only affected by long delays. Data from
applications or devices that lack QoS capabilities.
0, 3
AC_BK (AC1) Background Lowest priority. Data with no delay or throughput
requirements, such as bulk data transfers.
2, 1