11-WLAN Advanced Features Configuration Guide

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01-WLAN optimization configuration
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Configuring WLAN optimization

About WLAN optimization

Proper channel planning and power control policies during WLAN deployment are important for good performance. However, in live WLAN networks, channel overlapping, collisions, and interference can easily occur because the none-overlapping channels are limited but the number of WLAN devices always increases.

The WLAN optimization features can help you improve the quality and stability of a WLAN.

Restrictions and guidelines: WLAN optimization configuration

Use WLAN optimization commands under the guidance of H3C Support.

There is no fixed combination of features for optimizing a specific WLAN. Select and adjust the features based on the application effect and WLAN performance.

The overall performance of a WLAN is determined by the network architecture as well as channel and power planning. Therefore, the WLAN optimization features cannot significantly increase the performance of a WLAN. In practice, if the features can improve the WLAN performance by 3%, the optimization is considered successful.

Configuring rejection of weak-signal clients

About this task

This feature enables an AP to reject clients with an RSSI lower than the specified threshold to release channel resources and enhance WLAN performance.

Restrictions and guidelines

After you enable this feature, wireless clients with an RSSI lower than the threshold might fail to access the WLAN.

After a client accesses the WLAN, an AP will not log off the client with an RSSI lower than the threshold but will reject the client after it disconnects from the network.

To avoid client access failures, set an appropriate RSSI value when enabling this feature.

Procedure

1.     Enter system view.

system-view

2.     Enter WLAN radio interface view.

interface wlan-radio interface-number

3.     Configure rejection of weak-signal clients.

option client reject enable [ rssi rssi-value ]

By default, rejecting weak-signal clients is disabled.

Configuring AP-triggered client reassociation

About this task

A client with a low signal strength can roam to another AP only when its signal strength is lower than the manufacturer-defined signal strength for triggering roaming. Therefore, the client cannot obtain good network experience and service quality.

This feature enables an AP to send unsolicited deauthentication frames to a client when the signal strength of the client is lower than the specified RSSI threshold. Then, the client can reassociate with the AP or roam to another AP.

Restrictions and guidelines

To avoid unexpected client logoff, set an appropriate RSSI value when enabling this feature.

Procedure

1.     Enter system view.

system-view

2.     Enter WLAN radio interface view.

interface wlan-radio interface-number

3.     Configure AP-triggered client reassociation.

option client reconnect enable [ rssi rssi-value ] [ interval interval ]

By default, AP-triggered client reassociation is disabled.

Configuring hidden node protection

About this task

This feature enables clients to send RTS or CTS frames before transmitting frames to avoid interference from hidden nodes.

Restrictions and guidelines

This feature takes effect only on 802.11g, 802.11n, and 802.11ac clients.

Procedure

1.     Enter system view.

system-view

2.     Enter WLAN radio interface view.

interface wlan-radio interface-number

3.     Configure hidden node protection.

option client hide-node-protection enable

By default, hidden node protection is disabled.

Configuring multicast and broadcast buffering

About this task

With this feature enabled, the AC stops sending broadcast and multicast packets and buffers them if an associated client is in sleep state. This mechanism affects the performance of real-time multicast applications.

With this feature disabled, the AC directly sends all broadcast and multicast packets regardless of whether an associated client is in sleep state.

Restrictions and guidelines

As a best practice, set the power management parameter to the maximum value on wireless clients before you disable this feature.

Disabling this feature disables clients in sleep state from receiving some broadcast and multicast packets.

Procedure

1.     Enter system view.

system-view

2.     Enter WLAN radio interface view.

interface wlan-radio interface-number

3.     Configure multicast and broadcast buffering.

option broadcast-multicast-buffer { disable | enable [ limit limit ] }

By default, multicast and broadcast buffering is enabled.

Configuring channel reuse

About this task

This feature enables an AP to ignore packets with a signal strength lower than the specified channel reuse level. This mechanism enables the AP to obtain more radio resources and improves the performance of APs working on the same channel.

Restrictions and guidelines

Enabling this feature might add hidden nodes.

Procedure

1.     Enter system view.

system-view

2.     Enter WLAN radio interface view.

interface wlan-radio interface-number

3.     Configure channel reuse.

option channel-reuse-optimization { disable | enable level level }

By default, channel reuse is disabled.

Enabling or disabling an AP to ignore weak signals

About this task

An AP determines that the channel is still occupied even though the signals it detects are weak, and does not forward frames any more. Ignoring packets with a signal strength lower than the specified RSSI threshold can increase frame sending and receiving efficiency.

Restrictions and guidelines

Ignoring weak signals might cause collisions and interference among devices on the same channel.

To avoid packet receiving failures, set an appropriate RSSI value when enabling this feature.

Procedure

1.     Enter system view.

system-view

2.     Enter WLAN radio interface view.

interface wlan-radio interface-number

3.     Enable or disable the AP to ignore weak signals.

option signal-ignore { disable | enable rssi rssi-value }

By default, ignoring weak signals is disabled.

Configuring roaming navigation

About this task

802.11 protocols do not provide any client roaming control mechanisms and some clients cannot actively roam to APs with better signal strength.

Perform this task to decrease the transmit power for beacons or probe responses of an AP to enable clients to roam to APs with better signal strength.

If you set the transmit power for beacons or probe responses, the system uses the default transmit power to transmit other packets.

Procedure

1.     Enter system view.

system-view

2.     Enter WLAN radio interface view.

interface wlan-radio interface-number

3.     Configure roaming navigation.

option roam-navigation { disable | enable rssi rssi-value { beacon-power power-value | probe-response-power power-value } }

By default, roaming navigation is disabled.

Enabling or disabling an AP to decrease the sleep interval of clients

About this task

A wireless client in sleep state listens for traffic indication map (TIM) information in beacon frames to determine whether the associated AP has buffered packets for it. This feature enables an AP to modify the TIM information in beacon frames to decrease the sleep interval of wireless clients to improve transmission efficiency.

Procedure

1.     Enter system view.

system-view

2.     Enter WLAN radio interface view.

interface wlan-radio interface-number

3.     Enable or disable the AP to decrease the sleep interval of clients.

option keep-active { disable | enable }

By default, decreasing the sleep interval of clients is disabled.

Configuring RTS/CTS frame sending

About this task

When you enable this feature, APs send RTS/CTS frames before sending packets to avoid channel collision. When you disable this feature, APs do not send RTS/CTS frames before sending packets to save system resources and improve network throughput.

Restrictions and guidelines

Disabling this feature might cause hidden node issues.

Procedure

1.     Enter system view.

system-view

2.     Enter WLAN radio interface view.

interface wlan-radio interface-number

3.     Configure RTS/CTS frame sending.

option immediate-transmit { disable | enable }

By default, RTS/CTS frame sending is enabled.

Configuring channel sharing

About this task

When this feature is enabled, an AP sends or does not send packets according to whether the detected signals are stronger or weaker than the specified power level. This mechanism avoids channel collision and interference.

Procedure

1.     Enter system view.

system-view

2.     Enter WLAN radio interface view.

interface wlan-radio interface-number

3.     Configure channel sharing.

option channel-share { disable | enable power-level power-level }

By default, channel sharing is enabled.

Setting the maximum number of probe response attempts

About this task

Perform this task to reduce the number of probe responses sent by a radio to save resources and improve network performance.

Procedure

1.     Enter system view.

system-view

2.     Enter WLAN radio interface view.

interface wlan-radio interface-number

3.     Set the maximum number of probe response attempts.

option probe-response-try { disable | enable number }

By default, the maximum number of probe response attempts is 2.

Configuring link performance optimization

About this task

Perform this task to modify the packet fragmentation threshold to optimize link performance.

Procedure

1.     Enter system view.

system-view

2.     Enter WLAN radio interface view.

interface wlan-radio interface-number

3.     Configure link performance optimization.

option optimize-link-performance { inbound | outbound } { disable | enable } [ value ]

By default, link performance optimization is disabled.

Configuring transmit power adjustment

About this task

This feature enables an AP to use the adjusted transmit power to transmit packets.

Procedure

1.     Enter system view.

system-view

2.     Enter WLAN radio interface view.

interface wlan-radio interface-number

3.     Configure transmit power adjustment.

option capacity-adjust { disable | enable [ all ] { increase | decrease } value }

By default, transmit power adjustment is disabled.

Configuring per-packet transmit power control

About this task

This feature enables an AP to dynamically perform transmit power control on a per packet basis. For example, the AP reduces the transmit power when it sends packets to a client with high RSSI. This feature can reduce power consumption, radiation, and interference and improve user experience.

Restrictions and guidelines

This feature is not applicable to 5 GHz radios of 802.11ac APs.

Procedure

1.     Enter system view.

system-view

2.     Enter WLAN radio interface view.

interface wlan-radio interface-number

3.     Configure per-packet transmit power control.

option tpc { disable | enable [ minpower minpower | powerstep powerstep | rssistep rssistep | rssithreshold rssithreshold ] }

By default, per-packet transmit power control is disabled.

Configuring 802.11n packet suppression

About this task

Perform this task to suppress 802.11n packets by defining the maximum number of aggregated MPDUs and the maximum A-MPDU length. The two thresholds take effect at the same time. If either threshold is reached, the AP stops aggregation and sends the A-MPDU.

This feature prevents 802.11n clients from affecting the performance of 802.11a and 802.11b/g clients.

Procedure

1.     Enter system view.

system-view

2.     Enter WLAN radio interface view.

interface wlan-radio interface-number

3.     Configure 802.11n packet suppression.

option dot11n-restraint { disable | enable packet-number packet-number packet-length packet-length } [ inbound | outbound ] [ tid tid-number ]

By default, 802.11n packet suppression is disabled.

Configuring fast forwarding of AP-to-client data frames

About this task

This feature enables an AP to forward data frames to clients without extra processing (such as verification and counting) to improve processing efficiency.

Procedure

1.     Enter system view.

system-view

2.     Enter WLAN radio interface view.

interface wlan-radio interface-number

3.     Configure fast forwarding of AP-to-client data frames.

option client fast-forwarding enable level level-value

By default, fast forwarding of AP-to-client data frames is disabled.

Setting the maximum retransmissions and retries for an EAPOL-Key packet

About this task

In Robust Security Network Association (RSNA) authentication, an AP and a client use EAPOL-Key packets in the four-way handshake to negotiate the keys. After that, the AP and the client periodically exchange EAPOL-Key packets to update the keys.

During key negotiation or update, the AP keeps retransmitting an EAPOL-Key packet until a response is received or the maximum number of retries for an EAPOL-Key packet is reached.

The system starts to count the retries when the maximum number of retransmissions is reached.

For more information about RSN key negotiation or update, see WLAN Security Configuration Guide.

Restrictions and guidelines

To ensure successful RSN key negotiation or update, you can increase the maximum number of retransmissions and the maximum number of retries for an EAPOL-Key packet.

Procedure

1.     Enter system view.

system-view

2.     Enter service template view.

wlan service-template service-template-name

3.     Set the maximum number of retransmissions for an EAPOL-Key packet and the retransmission interval.

option 4-way-handshake resend max-count [ interval interval ]

By default, the maximum number of retransmissions for an EAPOL-Key packet is three, and the retransmission interval is 300 milliseconds.

4.     Set the maximum number of retries for an EAPOL-Key packet and the retry interval.

option 4-way-handshake retry max-count [ interval interval ]

By default, the maximum number of retries for an EAPOL-Key packet is three, and the retry interval is 5 seconds.

Configuring software retransmission

About this task

Perform this task to configure software retransmission and set the maximum number of software retransmissions for the specified type of packets.

Procedure

1.     Enter system view.

system-view

2.     Enter WLAN radio interface view.

interface wlan-radio interface-number

3.     Enable software retransmission and set the maximum number of software retransmissions.

rrop software-retry { unicast [ eap ] | broadcast-multicast } enable count count

By default, the maximum number of software retransmissions varies by device model.

Enabling client inspection

About this task

The client inspection feature enables you to view information about packets exchanged and time consumed in each stage of the client association process.

In the current software version, the client inspection feature supports only client association, client association failure, and IP address lease extension events.

Procedure

1.     Enter system view.

system-view

2.     Enable client inspection.

wlan client inspect enable

By default, client inspection is disabled.

Enabling data transmission holding during roaming

About this task

With this feature enabled, the device caches the packets during client roaming and sends the packets to the client after the client roams successfully to reduce the packet loss during client roaming. With this feature disabled, the device ages out the cached packets after a period of time and will not send the packets to the client. As a best practice, enable this feature in the packet loss-sensitive scenario.

Restrictions and guidelines

To make this feature take effect, enable client association at the AC and enable the AC to forward client data traffic.

This feature is not supported in an AC hierarchy network or inter-AC roaming network.

Procedure

1.     Enter system view.

system-view

2.     Enter service template view.

wlan service-template service-template-name

3.     Enable data transmission holding during roaming.

sacp roam-optimize traffic-hold enable

By default, data transmission holding during roaming is disabled.