Configuring WLAN QoS· 1

Overview·· 1

Terminology· 1

WMM protocol 1

Protocols and standards 3

Configuring WMM·· 3

Configuration restrictions and guidelines 3

Configuration procedure· 4

Displaying and maintaining WMM·· 5

WMM configuration examples 6

Configuring bandwidth guaranteeing· 8

Configuration procedure· 8

Displaying and maintaining bandwidth guaranteeing· 8

Bandwidth guaranteeing configuration example· 9

Configuring WLAN service-based client rate limiting· 11

Configuration procedure· 11

Displaying and maintaining client rate limiting· 11

Client rate limiting configuration example· 12

Troubleshooting· 13

EDCA parameter configuration failure· 13

SVP or CAC configuration failure· 13

 

Overview

An 802.11 network offers contention-based wireless access. To provide applications with QoS services, IEEE developed 802.11e for the 802.11-based WLAN architecture.

While IEEE 802.11e was being standardized, Wi-Fi Alliance defined the Wi-Fi Multimedia (WMM) standard to allow QoS provision devices of different vendors to interoperate. WMM makes a WLAN network capable of providing QoS services.

Terminology

·          WMM—A wireless QoS protocol designed to preferentially transmit packets with high priority, thus guaranteeing better QoS services for voice and video applications in a wireless network.

·          Enhanced distributed channel access (EDCA)—A channel contention mechanism designed by WMM to preferentially transmit packets with high priority and allocate more bandwidth to such packets.

·          Access category (AC)—Used for channel contention. WMM defines four access categories. They are AC-VO (voice) queue, AC-VI (video) queue, AC-BE (best-effort) queue, and AC-BK (background) queue in the descending order of priority. When contending for a channel, a high-priority AC queue preempts a low-priority AC queue.

·          Connection admission control (CAC)—Limits the number of clients that are using high-priority AC queues (including AC-VO and AC-VI queues) to guarantee sufficient bandwidth for existing high-priority traffic.

·          Unscheduled Automatic Power-Save Delivery (U-APSD)—A new power saving mechanism defined by WMM to enhance the power saving capability of clients.

·          SpectraLink voice priority (SVP)—A voice priority protocol designed by the SpectraLink company to guarantee QoS for voice traffic.

WMM protocol

The distributed coordination function (DCF) in 802.11 stipulates that access points (APs) and clients use the carrier sense multiple access with collision avoidance (CSMA/CA) access mechanism. APs or clients listen to the channel before they hold the channel for data transmission. When the specified idle duration of the channel times out, APs or clients randomly select a backoff slot within the contention window to perform backoff. The device that finishes backoff first gets the channel. With 802.11, all devices have the same idle duration and contention window. Therefore, they are equal when contending for a channel. In WMM, this fair contention mechanism is changed.

EDCA parameters

WMM assigns data packets in a basic service set (BSS) to four AC queues. By allowing a high-priority AC queue to have more channel contention opportunities than a low-priority AC queue, WMM offers different service levels to different AC queues.

WMM define a set of EDCA parameters for each AC queue, covering the following:

·          Arbitration inter-frame spacing number (AIFSN)—Different from the 802.11 protocol where the idle duration (set using DIFS) is a constant value, WMM can define an idle duration per AC queue. The idle duration increases as the AIFSN value increases (see Figure 1 for the AIFS durations).

·          Exponent form of CWmin (ECWmin) and exponent form of CWmax (ECWmax)—Determine the average backoff slots, which increases as the two values increase (see Figure 1 for the backoff slots).

·          Transmission opportunity limit (TXOPLimit)—Indicates the maximum time for which a user can hold a channel after a successful contention. The greater the TXOPLimit is, the longer the user can hold the channel. The value 0 indicates that the user can send only one packet each time it holds the channel.

Figure 1 Per-AC channel contention parameters in WMM

 

CAC admission policies

CAC requires that a client obtain permission of the AP before it can use a high-priority AC queue for transmission, guaranteeing bandwidth to the clients that have gained access. CAC controls real time traffic (AC-VO and AC-VI traffic) but not common data traffic (AC-BE and AC-BK traffic).

If a client wants to use a high-priority AC queue, it must send a request to the AP. The AP returns a positive or negative response based on either of the following admission control policies:

·          Channel utilization-based admission policy—The AP calculates the total time that the existing high-priority AC queues occupy the channel in one second, and then calculates the time that the requesting traffic will occupy the channel in one second. If the sum of the two values is smaller than or equal to the maximum hold time of the channel, the client can use the requested AC queue. Otherwise, the request is rejected.

·          Users-based admission policy—If the number of clients using high-priority AC queues plus the clients requesting for high-priority AC queues is smaller than or equal to the maximum number of high-priority AC queue clients, the request is accepted. Otherwise, the request is rejected. During calculation, a client is counted once even if it is using both the AC-VO and AC-VI queues.

U-APSD power-save mechanism

U-APSD improves the 802.11 APSD power saving mechanism. When associating clients with AC queues, you can specify some AC queues as trigger-enabled, some AC queues as delivery-enabled, and the maximum number of data packets that can be delivered after receiving a trigger packet. Both the trigger attribute and the delivery attribute can be modified when flows are established using CAC. When a client sleeps, the delivery-enabled AC queue packets destined for the client are buffered. The client must send a trigger-enabled AC queue packet to get the buffered packets. After the AP receives the trigger packet, packets in the transmit queue are sent. The number of sent packets depends on the agreement made when the client was admitted. AC queues without the delivery attribute store and transmit packets as defined in the 802.11 protocol.

SVP

SVP can assign packets with the protocol ID 119 in the IP header to a specific AC queue. SVP stipulates that random backoff is not performed for SVP packets. Therefore, you can set both ECWmin and ECWmax to 0 when there are only SVP packets in an AC queue.

ACK policy

WMM defines two ACK policies:

·          No ACK—When the no acknowledgement (No ACK) policy is used, the recipient does not acknowledge received packets during wireless packet exchange. This policy is suitable in the environment where communication quality is fine and interference is weak. While the No ACK policy helps improve transmission efficiency, it can cause increased packet loss when communication quality deteriorates. This is because when this policy is used, a sender does not retransmit packets that have not been received by the recipient.

·          Normal ACK—When the Normal ACK policy is used, the recipient acknowledges each received unicast packet.

Protocols and standards

·          802.11e-2005, Amendment 8: Medium Access Control (MAC) Quality of Service Enhancements, IEEE Computer Society, 2005

·          Wi-Fi, WMM Specification version 1.1, Wi-Fi Alliance, 2005

Configuring WMM

Configuration restrictions and guidelines

·          If CAC is enabled for an AC queue, CAC is also enabled for the AC queues with higher priority. For example, if you use the wmm edca client command to enable CAC for the AC-VI queue, CAC is also enabled for the AC-VO queue. However, enabling CAC for the AC-VO queue does not enable CAC for the AC-VI queue.

·          H3C recommends that you use the default EDCA parameter settings for APs and clients (except the TXOPLimit parameter for devices using 802.11b radio cards) unless it is necessary to modify the default settings.

·          When the radio card of a device is 802.11b, H3C recommends that you set the TXOPLimit values of the AC-BK, AC-BE, AC-VI, and AC-VO queues to 0, 0, 188, and 102, respectively.

·          The SVP packet mapping function takes effect only after you enable WMM.

Configuration procedure

To configure WMM:

 

Step	Command	Remarks
1.       Enter system view.	system-view	N/A
2.       Enter radio interface view.	interface wlan-radio radio-number	N/A
3.       Enable WMM.	wmm enable	By default, WMM is enabled. The 802.11n and 802.11ac protocols stipulate that all 802.11n and 802.11ac clients support WLAN QoS. Therefore, when the radio operates in 802.11an, 802.11gn, or 802.11ac mode, you must enable WMM. Otherwise, the associated 802.11n or 802.11ac clients may fail to communicate.
4.       Set the EDCA parameters of AC-VO or AC-VI queues for clients.	wmm edca client { ac-vo | ac-vi } { aifsn aifsn-value | ecw ecwmin ecwmin-value ecwmax ecwmax -value | txoplimit txoplimit-value | cac } *	Optional. By default, a client uses the default EDCA parameters shown in Table 1.
5.       Set the EDCA parameters of AC-BE or AC-BK queues for clients.	wmm edca client { ac-be | ac-bk } { aifsn aifsn-value | ecw ecwmin ecwmin-value ecwmax ecwmax -value | txoplimit txoplimit -value } *	Optional. By default, a client uses the default EDCA parameters shown in Table 1.
6.       Set the EDCA parameters and specify the ACK policy for the radio.	wmm edca radio { ac-vo | ac-vi | ac-be | ac-bk } { aifsn aifsn-value | ecw ecwmin ecwmin-value ecwmax ecwmax -value | txoplimit txoplimit -value | noack } *	Optional. By default, an AP uses the default EDCA parameters shown in Table 2 and uses the Normal ACK policy.
7.       Set the CAC policy.	wmm cac policy { channelutilization [ channelutilization-value ] | users [ users-number ] }	Optional. By default, the users-based admission policy applies, with the maximum number of users being 20.
8.       Map SVP packets to a specified AC queue.	wmm svp map-ac { ac-vi | ac-vo | ac-be | ac-bk }	Optional. By default, the SVP packet mapping function is disabled. SVP packet mapping applies to non WMM clients, and does not take effect on WMM clients.

 

Table 1 The default EDCA parameters for clients

AC queue	AIFSN	ECWmin	ECWmax	TXOP Limit
AC-BK queue	7	4	10	0
AC-BE queue	3	4	10	0
AC-VI queue	2	3	4	94
AC-VO queue	2	2	3	47

 

Table 2 The default EDCA parameters for APs

AC queue	AIFSN	ECWmin	ECWmax	TXOP Limit
AC-BK queue	7	4	10	0
AC-BE queue	3	4	6	0
AC-VI queue	1	3	4	94
AC-VO queue	1	2	3	47

 

Displaying and maintaining WMM

 

Task	Command	Remarks
Display client WMM statistics.	display wlan statistics client { all | mac-address mac-address } [ | { begin | exclude | include } regular-expression ]	Available in any view.
Display radio or client WMM configuration.	display wlan wmm { radio [ interface wlan-radio wlan-radio-number ] | client { all | interface wlan-radio wlan-radio-number | mac-address mac-address } } [ | { begin | exclude | include } regular-expression ]	Available in any view.
Clear radio or client WMM statistics.	reset wlan wmm { radio [ interface wlan-radio wlan-radio-number ] | client { all | interface wlan-radio wlan-radio-number | mac-address mac-address } }	Available in user view.

 

WMM configuration examples

Basic WMM configuration

1.        Network requirements

As shown in Figure 2, enable WMM on the fat AP, so that the fat AP and client can prioritize the traffic.

Figure 2 Network diagram

 

2.        Configuration procedure

# Configure interface WLAN-BSS 1 to use the 802.11e priority of the received packets for priority mapping.

<Sysname> system-view

[Sysname] interface wlan-bss 1

[Sysname-WLAN-BSS1] qos trust dot11e

[Sysname-WLAN-BSS1] quit

# Configure interface GigabitEthernet 1/0/1 to use the 802.1p priority of received packets for priority mapping.

[Sysname] interface gigabitethernet 1/0/1

[Sysname-GigabitEthernet1/0/1] qos trust dot1p

[Sysname-GigabitEthernet1/0/1] quit

# Create a clear-type WLAN service template, configure its SSID as market, configure its authentication method as Open System, and then enable the WLAN service template.

[Sysname] wlan service-template 1 clear

[Sysname-wlan-st-1] ssid market

[Sysname-wlan-st-1] authentication-method open-system

[Sysname-wlan-st-1] service-template enable

# Configure the radio type as 802.11gn for radio interface WLAN-Radio 1/0/2, and map service template 1 to interface WLAN-BSS1 on the radio interface.

[Sysname] interface wlan-radio 1/0/2

[Sysname-WLAN-Radio1/0/2] radio-type dot11gn

[Sysname-WLAN-Radio1/0/2] service-template 1 interface wlan-bss 1

# Enable WMM on radio interface WLAN-Radio 1/0/2.

[Sysname-WLAN-Radio1/0/2] wmm enable

[Sysname-WLAN-Radio1/0/2] quit

After WMM is enabled, you can use the display wlan wmm radio command to view WMM-related information.

CAC service configuration example

1.        Network requirements

As shown in Figure 3, a fat AP is connected to an Ethernet and has WMM enabled.

Enable CAC for the AC-VO and AC-VI queues of the fat AP. Use a users-based admission policy to allow up to 10 users to access, so that enough bandwidth can be guaranteed for the clients using high-priority queues (AC-VO and AC-VI queues).

Figure 3 Network diagram

 

2.        Configuration procedure

# Configure interface WLAN-BSS 1 to use the 802.11e priority of received packets for priority mapping.

<Sysname> system-view

[Sysname] interface wlan-bss 1

[Sysname-WLAN-BSS1] qos trust dot11e

[Sysname-WLAN-BSS1] quit

# Configure interface GigabitEthernet 1/0/1 to use the 802.1p priority of received packets for priority mapping.

[Sysname] interface gigabitethernet 1/0/1

[Sysname-GigabitEthernet1/0/1] qos trust dot1p

[Sysname-GigabitEthernet1/0/1] quit

# Create a clear-type WLAN service template, configure its SSID as market, configure its authentication method as Open System, and then enable the WLAN service template.

[Sysname] wlan service-template 1 clear

[Sysname-wlan-st-1] ssid market

[Sysname-wlan-st-1] authentication-method open-system

[Sysname-wlan-st-1] service-template enable

# Configure the radio type as 802.11gn for radio interface WLAN-Radio 1/0/2, and map service template 1 to interface WLAN-BSS1 on the radio interface.

[Sysname] interface wlan-radio 1/0/2

[Sysname-WLAN-Radio1/0/2] radio-type dot11gn

[Sysname-WLAN-Radio1/0/2] service-template 1 interface wlan-bss 1

# Configure radio interface WLAN-Radio 1/0/2 to allow up to ten users to use high-priority AC queues (including AC-VO and AC-VI queues).

[Sysname-WLAN-Radio1/0/2] wmm edca client ac-vo cac

[Sysname-WLAN-Radio1/0/2] wmm edca client ac-vi cac

[Sysname-WLAN-Radio1/0/2] wmm cac policy users 10

[Sysname-WLAN-Radio1/0/2] wmm enable

[Sysname-WLAN-Radio1/0/2] quit

If a client wants to use a high-priority AC queue (AC-VO or AC-VI queue), it must send a request to the AP. If the number of clients using high-priority AC queues (including AC-VO and AC-VI queues) plus the clients requesting for high-priority AC queues on the AP is smaller than or equal to the maximum number of high-priority AC clients (10 in this example), the request is accepted. If the number of client exceeds the maximum number of high-priority AC clients, the system decreases the priority of the packets from the excessive clients.

Configuring bandwidth guaranteeing

This feature is unavailable when a radio operates in 802.11ac mode.

When traffic is heavy, a BSS without any rate limitation may aggressively occupy the available bandwidth for other BSSs. If you limit the rate of the BSS, it cannot use the idle bandwidth of other BSSs.

To improve bandwidth use efficiency when ensuring bandwidth use fairness among WLAN services, use the bandwidth guaranteeing function. Bandwidth guaranteeing makes sure all traffic from each BSS can pass through freely when the network is not congested, and each BSS can get the guaranteed bandwidth when the network is congested. For example, suppose you guarantee SSID1, SSID2, and SSID3 25%, 25%, and 50% of the bandwidth. When the network is not congested, SSID1 can use all idle bandwidth in addition to its guaranteed bandwidth. When the network is congested, SSID1 can use at least its guaranteed bandwidth, 25% of the bandwidth.

This feature applies to only the traffic from AP to client.

Configuration procedure

Before configuring bandwidth guaranteeing, you can use the dot11a/dot11b/dot11g/dot11n max-bandwidth command to specify the maximum bandwidth value for each radio. For more information, see "Configuring WLAN RRM."

To configure bandwidth guaranteeing:

 

Step	Command	Remarks
1.       Enter system view.	system-view	N/A
2.       Enter radio interface view.	interface wlan-radio radio-number	N/A
3.       Enable bandwidth guaranteeing.	bandwidth-guarantee enable	By default, bandwidth guaranteeing is disabled.
4.       Configure a guaranteed bandwidth percent for the specified service template.	bandwidth-guarantee service-template service-template-number percent percent	Optional. The service template must have been bound to the radio. For the service templates bound to the same radio, the sum of guaranteed bandwidth percents cannot exceed 100%.

 

Displaying and maintaining bandwidth guaranteeing

 

Task	Command	Remarks
Display bandwidth guaranteeing configuration.	display wlan bandwidth-guarantee [ interface radio-interface-name ] [ | { begin | exclude | include } regular-expression ]	Available in any view.

 

Bandwidth guaranteeing configuration example

Network requirements

In an enterprise, three clients access the wireless network through WLAN services research, office, and entertain, respectively.

To make sure the enterprise network operate properly, guarantee 20% of the bandwidth for WLAN service office, 80% for research, and none for entertain with the same fat AP.

Figure 4 Network diagram

 

 

Configuration procedure

# Set the maximum bandwidth to 10000 kbps for the 802.11a radio.

<AP> system-view

[AP] wlan rrm

[AP-wlan-rrm] dot11a max-bandwidth 10000

[AP-wlan-rrm] quit

# Create a WLAN-BSS interface.

[AP] interface wlan-bss 1

[AP-WLAN-BSS1] port-security port-mode psk

[AP-WLAN-BSS1] port-security tx-key-type 11key

[AP-WLAN-BSS1] port-security preshared-key pass-phrase simple 12345678

[AP-WLAN-BSS1] quit

[AP] interface wlan-bss 2

[AP-WLAN-BSS2] port-security port-mode psk

[AP-WLAN-BSS2] port-security tx-key-type 11key

[AP-WLAN-BSS2] port-security preshared-key pass-phrase simple abcdefgh

[AP-WLAN-BSS2] quit

[AP] interface wlan-bss 3

[AP-WLAN-BSS3] quit

# Create service template 1 of the crypto type, and set the SSID as research for service template 1.

[AP] wlan service-template 1 crypto

[AP-wlan-st-1] ssid research

[AP-wlan-st-1] authentication-method open-system

[AP-wlan-st-1] cipher-suite ccmp

[AP-wlan-st-1] security-ie rsn

[AP-wlan-st-1] service-template enable

[AP-wlan-st-1] quit

# Create service template 2 of the crypto type, and set the SSID as office for service template 2.

[AP] wlan service-template 2 crypto

[AP-wlan-st-2] ssid office

[AP-wlan-st-2] authentication-method open-system

[AP-wlan-st-2] cipher-suite ccmp

[AP-wlan-st-2] security-ie rsn

[AP-wlan-st-2] service-template enable

[AP-wlan-st-2] quit

# Create service template 3 of the clear type, and set the SSID as entertain for service template 2.

[AP] wlan service-template 3 clear

[AP-wlan-st-3] ssid entertain

[AP-wlan-st-3] service-template enable

[AP-wlan-st-3] quit

# Bind WLAN-BSS interfaces to the WLAN service templates on interface WLAN-Radio 1/0/1.

[AP] interface wlan-radio 1/0/1

[AP-WLAN-Radio1/0/1] radio-type dot11a

[AP-WLAN-Radio1/0/1] service-template 1 interface wlan-bss 1

[AP-WLAN-Radio1/0/1] service-template 2 interface wlan-bss 2

[AP-WLAN-Radio1/0/1] service-template 3 interface wlan-bss 3

# Enable bandwidth guaranteeing.

[AP-WLAN-Radio1/0/1] bandwidth-guarantee enable

# Set the guaranteed bandwidth percent to 80% for service template 1 and 20% for service template 2.

[AP-WLAN-Radio1/0/1] bandwidth-guarantee service-template 1 percent 80

[AP-WLAN-Radio1/0/1] bandwidth-guarantee service-template 2 percent 20

[AP-WLAN-Radio1/0/1] return

Verifying the configuration

# Use the display wlan bandwidth-guarantee command to display the bandwidth guaranteeing configuration.

<AP> display wlan bandwidth-guarantee interface wlan-radio 1/0/1

                            Bandwidth Guarantee

--------------------------------------------------------------------------------

 Radio                           Mode            Service-Template   Percent

--------------------------------------------------------------------------------

 WLAN-Radio1/0/1                 802.11a         1                  80%

 WLAN-Radio1/0/1                 802.11a         2                  20%

--------------------------------------------------------------------------------

1.        When the total traffic rate from the AP to all clients is lower than 10000 kbps, the rate of traffic from the AP to any client is not limited.

2.        Suppose the rate of traffic from the AP to Client 1 exceeds 2000 kbps and the rate of traffic from the AP to Client 2 exceeds 8000 kbps, and the rate of traffic from the AP to all clients exceeds 10000 kbps. In this case, because WLAN services research and office are configured with bandwidth guaranteeing, the AP will preferentially forward traffic from the AP to Client 1 and Client 2. As a result, the AP sends traffic to Client 1 at a rate of 2000 kbps, the AP sends traffic to client 2 at a rate of 8000 kbps, and the rate of traffic from the AP to Client 3 is limited.

Configuring WLAN service-based client rate limiting

The WLAN provides limited bandwidth for each AP. Because the bandwidth is shared by wireless clients attached to the AP, aggressive use of bandwidth by a client will affect other clients. To ensure fair use of bandwidth, rate limit traffic of clients in either of the following approaches:

·          Configure the total bandwidth shared by all clients. This is called "dynamic mode." The rate limit of a client is the configured total rate/the number of online clients. For example, if the configure total rate is 10 Mbps and five clients are online, the rate limit of each client is 2 Mbps.

·          Configure the maximum bandwidth that can be used by each client. This is called "static mode." For example, if the configured rate is 1 Mbps, the rate limit of each client online is 1 Mbps. When the set rate limit multiplied by the number of access clients exceeds the available bandwidth provided by the AP, no clients can get the guaranteed bandwidth.

Configuration procedure

You can configure WLAN service-based client rate limiting, so that the AP can limit client rates for a WLAN service.

To configure WLAN service-based client rate limiting:

 

Step	Command	Remarks
1.       Enter system view.	system-view	N/A
2.       Enter service template view.	wlan service-template service-template-number { clear | crypto }	N/A
3.       Configure WLAN service-based client rate limiting.	client-rate-limit direction { inbound | outbound } mode { dynamic | static } cir cir	By default, WLAN service-based client rate limiting is disabled.

 

Displaying and maintaining client rate limiting

 

Task	Command	Remarks
Display client rate limiting information.	display wlan client-rate-limit service-template [ service-template-number ] [ | { begin | exclude | include } regular-expression ]	Available in any view.

 

Client rate limiting configuration example

Network requirements

The fat AP is connected to a Layer 2 switch. Configure client rate limiting on the fat AP, so that the fat AP limits the incoming traffic in static mode and limits the outgoing traffic in dynamic mode for the clients.

Figure 5 Network diagram

 

Configuration procedure

# Create a WLAN-BSS interface.

<AP> system-view

[AP] interface wlan-bss 1

[AP-WLAN-BSS1] quit

# Create service template 1 of the clear type, and configure the authentication mode as open-system.

[AP] wlan service-template 1 clear

[AP-wlan-st-1] ssid service

[AP-wlan-st-1] authentication-method open-system

# Configure WLAN service-based client rate limiting on the fat AP to limit the rate of traffic from clients to AP (incoming traffic) to 8000 kbps in static mode and the rate of traffic from AP to clients (outgoing traffic) to 8000 kbps in dynamic mode.

[AP-wlan-st-1] client-rate-limit direction inbound mode static cir 8000

[AP-wlan-st-1] client-rate-limit direction outbound mode dynamic cir 8000

[AP-wlan-st-1] service-template enable

[AP-wlan-st-1] quit

# Bind WLAN-BSS interface 1 to the WLAN service template 1 on interface WLAN-Radio 1/0/2.

[AP] interface wlan-radio 1/0/2

[AP-WLAN-Radio1/0/2] radio-type dot11gn

[AP-WLAN-Radio1/0/2] channel 1

[AP-WLAN-Radio1/0/2] service-template 1 interface wlan-bss 1

[AP-WLAN-Radio1/0/2] return

Verifying the configuration

# Use the display wlan client-rate-limit service-template command to display the client rate limiting configuration.

<AP> display wlan client-rate-limit service-template

                            Client Rate Limit

--------------------------------------------------------------------------------

 Service Template       Direction       Mode            CIR(kbps)

--------------------------------------------------------------------------------

 1                      Inbound         Static          8000

 1                      Outbound        Dynamic         8000

--------------------------------------------------------------------------------

1.        When only Client 1 accesses the WLAN through SSID service, the available bandwidth is limited to around 8000 kbps.

2.        When both Client 1 and Client 2 access the WLAN through SSID service, the bandwidth available for the traffic from either Client 1 or Client 2 to the AP is limited to around 8000 kbps, and the bandwidth available for the traffic from the AP to either Client 1 or Client 2 is limited to around 4000 kbps.

Troubleshooting

EDCA parameter configuration failure

Symptom

Configuring EDCA parameters for an AP failed.

Analysis

The EDCA parameter configuration of an AP is restricted by the radio chip of the AP.

Solution

1.        Use the display wlan wmm radio command to view the support of the radio chip for the EDCA parameters. Make sure the configured EDCA parameters are supported by the radio chip.

2.        Check that the values configured for the EDCA parameters are valid.

SVP or CAC configuration failure

Symptom

The SVP packet priority mapping function configured with the wmm svp map-ac command does not take effect.

CAC configured with the wmm edca client command does not take effect.

Analysis

The SVP packet priority mapping function or CAC takes effect only after WMM is enabled.

Solution

1.        Use the wmm enable command to enable the WMM function.

2.        Check the state of the SVP priority mapping function or CAC again.

3.        The SVP packet priority mapping function takes effect on only non-WMM clients. Check whether the client is a non-WMM client.