Using the Rogue AP Monitor

Go to Monitor > Rogue AP Monitor to view the list of other wireless access points that are receivable at your location.

Information Columns Actual columns displayed depends on Column Settings.

Rogue AP — Use this status for unauthorized APs that On-wire status indicates are attached to your wired networks. Accepted AP — Use this status for APs that are an authorized part of your network or Stateare neighboring APs that are not a security threat. To see accepted APs in the list, select Show Accepted. Unclassified — This is the initial status of a discovered AP. You can change an AP back to unclassified if you have mistakenly marked it as Rogue or Accepted.

OnlineActive AP Status Inactive AP Active ad-hoc WiFi device Inactive ad-hoc WiFi device

SSID            The wireless service set identifier (SSID) or network name for the wireless interface.

Security           The type of security currently being used. Type

Channel       The wireless radio channel that the access point uses.

MAC     The MAC address of the Wireless interface. Address

Vendor The name of the vendor. Info

Signal  The relative signal strength of the AP. Mouse over the symbol to view the signal-to-noise Strength           ratio.

Detected The name or serial number of the AP unit that detected the signal. By

On-wire         A green up-arrow indicates a suspected rogue, based on the on-wire detection technique. A red down-arrow indicates AP is not a suspected rogue.

First Seen     How long ago this AP was first detected.

Suppressing

Last Seen	How long ago this AP was last detected.
Rate	Data rate in bps.

To change the Online Status of an AP, right-click it and select Mark Accepted or Mark Rogue.

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Configuring rogue scanning

All APs using the same FortiAP Profile share the same rogue scanning settings, unless override is configured.

To enable rogue AP scanning with on-wire detection – web-based manager

1. Go to WiFi & Switch Controller > WIDS Profiles.

On some models, the menu is WiFi & Switch Controller.

2. Select an existing WIDS Profile and edit it, or select Create New.
3. Make sure that Enable Rogue AP Detection is selected.
4. Select Enable On-Wire Rogue AP Detection.
5. Optionally, enable Auto Suppress Rogue APs in Foreground Scan.
6. Select OK.

To enable the rogue AP scanning feature in a custom AP profile – CLI

config wireless-controller wids-profile edit FAP220B-default set ap-scan enable set rogue-scan enable

end

Exempting an AP from rogue scanning

By default, if Rogue AP Detection is enabled, it is enabled on all managed FortiAP units. Optionally, you can exempt an AP from scanning. You should be careful about doing this if your organization must perform scanning to meet PCI-DSS requirements.

Monitoring

To exempt an AP from rogue scanning – web-based manager

1. Go to WiFi & Switch Controller > Managed FortiAPs.
2. Select which AP to edit.
3. In Wireless Settings, enable Override Settings.
4. Select Do not participate in Rogue AP Scanning and then select OK.

To exempt an AP from rogue scanning – CLI

This example shows how to exempt access point AP1 from rogue scanning.

config wireless-controller wtp edit AP1 set override-profile enable set ap-scan disable

end

MAC adjacency

You can adjust the maximum WiFi to Ethernet MAC difference used when determining whether an suspect AP is a rogue.

To adjust MAC adjacency

For example, to change the adjacency to 8, enter

config wireless-controller global set rogue-scan-mac-adjacency 8 end

Monitoring rogue APs                                                                                                  Wireless network monitoring

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Rogue AP scanning as a background activity

Each WiFi radio can perform monitoring of radio channels in its operating band while acting as an AP. It does this by briefly switching from AP to monitoring mode. By default, a scan period starts every 300 seconds. Each second a different channel is monitored for 20ms until all channels have been checked.

Monitoring rogue APs                                                                                                  Wireless network monitoring

During heavy AP traffic, it is possible for Spectrum Analysis background scanning to cause lost packets when the radio switches to monitoring. To reduce the probability of lost packets, you can set the CLI ap-bgscan-idle field to delay the switch to monitoring until the AP has been idle for a specified period. This means that heavy AP traffic may slow background scanning.

The following CLI example configures default background rogue scanning operation except that it sets apbgscan-idle to require 100ms of AP inactivity before scanning the next channel.

config wireless-controller wtp-profile edit ourprofile config radio-1 set wids-profile ourwidsprofile set spectrum-analysis enable

end

end

config wireless-controller wids-profile edit ourwidsprofile set ap-scan enable set rogue-scan enable set ap-bgscan-period 300 set ap-bgscan-intv 1 set ap-bgscan-duration 20 set ap-bgscan-idle 100

end

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On-wire rogue AP detection technique

Other APs that are available in the same area as your own APs are not necessarily rogues. A neighboring AP that has no connection to your network might cause interference, but it is not a security threat. A rogue AP is an unauthorized AP connected to your wired network. This can enable unauthorized access. When rogue AP detection is enabled, the On-wire column in the Rogue AP Monitor list shows a green up-arrow on detected rogues.

Rogue AP monitoring of WiFi client traffic builds a table of WiFi clients and the Access Points that they are communicating through. The FortiGate unit also builds a table of MAC addresses that it sees on the LAN. The FortiGate unit’s on-wire correlation engine constantly compares the MAC addresses seen on the LAN to the MAC addresses seen on the WiFi network.

There are two methods of Rogue AP on-wire detection operating simultaneously: Exact MAC address match and MAC adjacency.

Exact MAC address match

If the same MAC address is seen on the LAN and on the WiFi network, this means that the wireless client is connected to the LAN. If the AP that the client is using is not authorized in the FortiGate unit configuration, that AP is deemed an ‘on-wire’ rogue. This scheme works for non-NAT rogue APs.

MAC adjacency

If an access point is also a router, it applies NAT to WiFi packets. This can make rogue detection more difficult.

However, an AP’s WiFi interface MAC address is usually in the same range as its wired MAC address. So, the MAC adjacency rogue detection method matches LAN and WiFi network MAC addresses that are within a defined numerical distance of each other. By default, the MAC adjacency value is 7. If the AP for these matching MAC addresses is not authorized in the FortiGate unit configuration, that AP is deemed an ‘on-wire’ rogue.

Limitations

On-wire rogue detection has some limitations. There must be at least one WiFi client connected to the suspect AP and continuously sending traffic. If the suspect AP is a router, its WiFi MAC address must be very similar to its Ethernet port MAC address.

Logging

Information about detected rogue APs is logged and uploaded to your FortiAnalyzer unit, if you have one. By default, rogue APs generate an alert level log, unknown APs generate a warning level log. This log information can help you with PCI-DSS compliance requirements.

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Monitoring rogue APs

The access point radio equipment can scan for other available access points, either as a dedicated monitor or in idle periods during AP operation.

 

Monitoring

Discovered access points are listed in Monitor > Rogue AP Monitor. You can then mark them as either Accepted or Rogue access points. This designation helps you to track access points. It does not affect anyone’s ability to use these access points.

It is also possible to suppress rogue APs. See Monitoring rogue APs on page 111.

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Monitoring wireless clients

To view connected clients on a FortiWiFi unit

1. Go to Monitor > Client Monitor.

The following information is displayed:

SSID	The SSID that the client connected to.
FortiAP	The serial number of the FortiAP unit to which the client connected.
User	User name
IP	The IP address assigned to the wireless client.
Device
Auth	The type of authentication used.
Channel	WiFi radio channel in use.
Bandwidth Tx/Rx	Client received and transmitted bandwidth, in Kbps.
Signal Strength / Noise	The signal-to-noise ratio in deciBels calculated from signal strength and noise level.
Signal Strength
Association Time	How long the client has been connected to this access point.

Results can be filtered. Select the filter icon on the column you want to filter. Enter the values to include or select NOT if you want to exclude the specified values.

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Protecting the WiFi Network

Wireless IDS

WiFi data channel encryption

Protected Management Frames and Opportunisitc Key Caching support

Wireless IDS

The FortiGate Wireless Intrusion Detection System (WIDS) monitors wireless traffic for a wide range of security threats by detecting and reporting on possible intrusion attempts. When an attack is detected the FortiGate unit records a log message.

You can create a WIDS profile to enable these types of intrusion detection:

• Asleap Attack—ASLEAP is a tool used to perform attacks against LEAP authentication.
• Association Frame Flooding—A Denial of Service attack using a large number of association requests. The default detection threshold is 30 requests in 10 seconds.
• Authentication Frame Flooding—A Denial of Service attack using a large number of association requests. The default detection threshold is 30 requests in 10 seconds.
• Broadcasting De-authentication—This is a type of Denial of Service attack. A flood of spoofed de-authentication frames forces wireless clients to de-athenticate, then re-authenticate with their AP.
• EAPOL Packet Flooding—Extensible Authentication Protocol over LAN (EAPOL) packets are used in WPA and WPA2 authentication. Flooding the AP with these packets can be a denial of service attack. Several types of EAPOL packets are detected: EAPOL-FAIL, EAPOL-LOGOFF, EAPOL-START, EAPOL-SUCC.
• Invalid MAC OUI—Some attackers use randomly-generated MAC addresses. The first three bytes of the MAC address are the Organizationally Unique Identifier (OUI), administered by IEEE. Invalid OUIs are logged.
• Long Duration Attack—To share radio bandwidth, WiFi devices reserve channels for brief periods of time. Excessively long reservation periods can be used as a denial of service attack. You can set a threshold between 1000 and 32 767 microseconds. The default is 8200. l Null SSID Probe Response—When a wireless client sends out a probe request, the attacker sends a response with a null SSID. This causes many wireless cards and devices to stop responding.
• Spoofed De-authentication—Spoofed de-authentication frames are a denial of service attack. They cause all clients to disconnect from the AP.
• Weak WEP IV Detection—A primary means of cracking WEP keys is by capturing 802.11 frames over an extended period of time and searching for patterns of WEP initialization vectors (IVs) that are known to be weak. WIDS detects known weak WEP IVs in on-air traffic.
• Wireless Bridge—WiFi frames with both the fromDS and ToDS fields set indicate a wireless bridge. This will also detect a wireless bridge that you intentionally configured in your network.

You can enable wireless IDS by selecting a WIDS Profile in your FortiAP profile.

To create a WIDS Profile

1. Go to WiFi & Switch Controller > WIDS Profiles.
2. Select a profile to edit or select Create New.

WiFi data channel encryption                                                                                          Protecting the WiFi Network

3. Select the types of intrusion to protect against. By default, all types are selected.
4. Select Apply.

You can also configure a WIDS profile in the CLI using the config wireless-controller widsprofile command.

Rogue AP detection

The WIDS profile includes settings for detection of unauthorized (rogue) access points in your wireless network. For more information, see Wireless network monitoring on page 111.

WIDS client deauthentication rate for DoS attacks

As part of mitigating a Denial of Service (DoS) attack, the FortiGate sends deauthentication packets to unknown clients. In an aggressive attack, this deauthentication activity can prevent the processing of packets from valid clients. A WIDS Profile option in the CLI limits the deauthentication rate.

config wireless-controller wids-profile edit default set deauth-unknown-src-thresh <1-65535>

end

The value set is a measure of the number of deathorizations per second. 0 means no limit. The default is 10.

WiFi data channel encryption

Optionally, you can apply DTLS encryption to the data channel between the wireless controller and FortiAP units. This enhances security.

There are data channel encryption settings on both the FortiGate unit and the FortiAP units. At both ends, you can enable Clear Text, DTLS encryption, or both. The settings must agree or the FortiAP unit will not be able to join the WiFi network. By default, both Clear Text and DTLS-encrypted communication are enabled on the FortiAP unit, allowing the FortiGate setting to determine whether data channel encryption is used. If the FortiGate unit also enables both Clear Text and DTLS, Clear Text is used.

Data channel encryption settings are located in the FortiAP profile. By default, only Clear Text is supported.

Configuring encryption on the FortiGate unit

You can use the CLI to configure data channel encryption.

Enabling encryption

In the CLI, the wireless wtp-profile command contains a new field, dtls-policy, with options clear-text and dtls-enabled. To enable encryption in profile1 for example, enter:

config wireless-controller wtp-profile

Protecting the WiFi Network                              Protected Management Frames and Opportunisitc Key Caching support

edit profile1 set dtls-policy dtls-enabled

end

Configuring encryption on the FortiAP unit

The FortiAP unit has its own settings for data channel encryption.

Enabling CAPWAP encryption – FortiAP web-based manager

1. On the System Information page, in WTP Configuration > AC Data Channel Security, select one of:

l Clear Text l DTLS Enabled l Clear Text or DTLS Enabled (default)

2. Select Apply.

Enabling encryption – FortiAP CLI

You can set the data channel encryption using the AC_DATA_CHAN_SEC variable: 0 is Clear Text, 1 is DTLS Enabled, 2 (the default) is Clear Text or DTLS Enabled.

For example, to set security to DTLS and then save the setting, enter

cfg -a AC_DATA_CHAN_SEC=1 cfg -c

Protected Management Frames and Opportunisitc Key Caching support

Protected Management Frames (PMF) protect some types of management frames like deauthorization, disassociation and action frames. This feature, now mandatory on WiFi certified 802.1ac devices, prevents attackers from sending plain deauthorization/disassociation frames to disrupt or tear down a connection/association. PMF is a Wi-Fi Alliance specification based on IEEE 802.11w.

To facilitate faster roaming client roaming, you can enable Opportunistic Key Caching (OKC) on your WiFi network. When a client associates with an AP, its PMK identifier is sent to all other APs on the network. This eliminates the need for an already-authenticated client to repeat the full EAP exchange process when it roams to another AP on the same network.

Use of PMF and OKC on an SSID is configurable only in the CLI:

config wireless-controller vap edit <vap_name> set pmf {disable | enable | optional} set pmf-assoc-comeback-timeout <integer> set pmf-sa-query-retry-timeout <integer>

set okc {disable | enable}

next

end

When pmf is set to optional, it is considered enabled, but will allow clients that do not use PMF. When pmf is set to enable, PMF is required by all clients.

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Using Remote WLAN FortiAPs

Remote WLAN FortiAP models enable you to provide a pre-configured WiFi access point to a remote or traveling employee. Once plugged in at home or in a hotel room, the FortiAP automatically discovers the enterprise FortiGate WiFi controller over the Internet and broadcasts the same wireless SSID used in the corporate office. Communication between the WiFi controller and the FortiAP is secure, eliminating the need for a VPN.

Split tunneling

By default, all traffic from the remote FortiAP is sent to the FortiGate WiFi controller. If split tunneling is configured, only traffic destined for the corporate office networks is routed to the FortiGate unit. Other general Internet traffic is routed unencrypted through the local gateway. Split tunneling avoids loading the FortiGate unit with unnecessary traffic and allows direct access to local private networks at the FortiAP’s location even if the connection to the WiFi controller goes down.

Note: Split tunneling in WiFi networks differs in implementation from split tunneling in VPN configurations.

By default, split tunneling options are not visible in the FortiGate GUI. You can make these options visible using the following CLI command:

config system settings set gui-fortiap-split-tunneling enable

end

Split tunneling is configured in Managed FortiAPs, FortiAP Profiles, and enabled in the SSID.

Configuring the FortiGate for remote FortiAPs

This section assumes that you have already defined SSIDs and now want to make them available to remote FortiAPs.

• Create FortiAP profiles for the Remote LAN FortiAP models l If split tunneling will be used l configure override split tunneling in Managed FortiAPs l enable Split Tunneling in the SSID
• configure the split tunnel networks in the FortiAP profile

Override Split Tunneling

Go to WiFi & Switch Controller > Managed FortiAPs and edit your managed APs. When preconfiguring the AP to connect to your FortiGate WiFi controller, you can choose to override split tunneling, optionally including the local subnet of the FortiAP.

Creating FortiAP profiles

If you were not already using Remote LAN FortiAP models, you will need to create FortiAP profiles for them. In the FortiAP profile, you specify the SSIDs that the FortiAP will broadcast. For more information, see “Creating a FortiAP Profile” on page 43.

Configuring the FortiGate for remote FortiAPs                                                              Using Remote WLAN FortiAPs

Configuring split tunneling – FortiGate GUI

Go to WiFi & Switch Controller > SSID and edit your SSID. In the WiFi Settings section, enable Split Tunneling.

Go to WiFi Controller > FortiAP Profiles and edit the FortiAP Profile(s) that apply to the AP types used in the WiFi network. In the Split Tunneling section, enable Include Local Subnet and Split Tunneling Subnet(s), where you can enter a list all of the destination IP address ranges that should not be routed through the the FortiGate WiFi controller. Packets for these destinations will instead be routed through the remote gateway local to the FortiAP.

The list of split tunneling subnets includes public Internet destinations and private subnets local to the FortiAP. Split tunneling public Internet destinations reduces traffic through the FortiGate unit. Split tunneling local private subnets allows these networks to be accessible to the client behind the FortiAP. Otherwise, private network IP destinations are assumed to be behind the FortiGate WiFi controller.

Configuring split tunneling – FortiGate CLI

In this example, split tunneling is configured on the example-ssid WiFi network. On FortiAP model 21D, traffic destined for the 192.168.x.x range will not be routed through the FortiGate WiFi controller. This private IP address range is typically used as a LAN by home routers.

config wireless-controller vap edit example-ssid set split-tunneling enable

end

config wireless-controller wtp-profile edit FAP21D-default set split-tunneling-acl-local-ap-subnet enable config split-tunneling-acl edit 1 set dest-ip 192.168.0.0 255.255.0.0

end

end

To enter multiple subnets, create a split-tunneling-acl entry for each one.

Overriding the split tunneling settings on a FortiAP

If the FortiAP Profile split tunneling settings are not appropriate for a particular FortiAP, you can override the settings on that unit.

config wireless-controller wtp edit FAP321C3X14019926 set override-split-tunnel enable

set split-tunneling-acl-local-ap-subnet enable config split-tunneling-acl edit 1 set dest-ip 192.168.10.0 255.255.255.0

end end

Using Remote WLAN FortiAPs                                                                                     Configuring the FortiAP units

Configuring the FortiAP units

Prior to providing a Remote WLAN FortiAP unit to an employee, you need to preconfigure the AP to connect to your FortiGate WiFi controller.

To pre-configure a FortiAP

1. Connect the FortiAP to the FortiGate unit.
2. Go to WiFi & Switch Controller > Managed FortiAPs and wait for the FortiAP to be listed. Click Refresh periodically to see the latest information. Note the Connected Via IP address.
3. Go to Dashboard. In the CLI Console, log into the FortiAP CLI. For example, if the IP address is 192.168.1.4, enter:

exec telnet 192.168.1.4

Enter admin at the login prompt. By default, no password is set.

4. Enter the following commands to set the FortiGate WiFi controller IP address. This should be the FortiGate Internet-facing IP address, in this example 172.20.120.142.

cfg -a AC_IPADDR_1=172.20.120.142 cfg -c

5. Enter exit to log out of the FortiAP CLI.

Preauthorizing FortiAP units

By preauthorizing FortiAP units, you facilitate their automatic authorization on the network. Also, you can assign each unit a unique name, such as the employee’s name, for easier tracking.

1. Go to WiFi & Switch Controller > Managed FortiAPs and create a new entry.
2. Enter the Serial Number of the FortiAP unit and give it a Name. Select the appropriate FortiAP Profile.
3. Click OK.

Repeat this process for each FortiAP.

Features for high-density deployments

High-density environments such as auditoriums, classrooms, and meeting rooms present a challenge to WiFi providers. When a large number of mobile devices try to connect to a WiFi network, difficulties arise because of the limited number of radio channels and interference between devices.

FortiOS and FortiAP devices provide several tools to mitigate the difficulties of high-density environments.

Power save feature

Occasionally, voice calls can become disrupted. One way to alleviate this issue is by controlling the power save feature, or to disable it altogether.

Manually configure packet transmit optimization settings by entering the following command:

config wireless-controller wtp-profile edit <name> config <radio-1> | <radio-2> set transmit-optimize {disable | power-save | aggr-limit | retry-limit | sendbar}

l disable: Disable transmit optimization. l power-save: Mark a client as power save mode if excessive transmit retries happen. l aggr-limit: Set aggregation limit to a lower value when data rate is low. l retry-limit: Set software retry limit to a lower value when data rate is low. l send-bar: Do not send BAR frame too often.

Broadcast packet suppression

Broadcast packets are sent at a low data rate in WiFi networks, consuming valuable air time. Some broadcast packets are unnecessary or even potentially detrimental to the network and should be suppressed.

ARP requests and replies could allow clients to discover each other’s IP addresses. On most WiFi networks, intraclient communication is not allowed, so these ARP requests are of no use, but they occupy air time.

DHCP (upstream) should be allowed so that clients can request an IP address using DHCP.

DHCP (downstream) should be suppressed because it would allow a client to provide DHCP service to other clients. Only the AP should do this.

NetBIOS is a Microsoft Windows protocol for intra-application communication. Usually this is not required in highdensity deployments.

IPv6 broadcast packets can be suppressed if your network uses IPv4 addressing.

You can configure broadcast packet suppression in the CLI. The following options are available for broadcast suppression:

config wireless-controller vap edit <name>

Features for high-density deployments                                                                        Multicast to unicast conversion

set broadcast-suppression {dhcp-up | dhcp-down | dhcp-starvation | arp-known | arpunknown | arp-reply | arp-poison | arp-proxy | netbios-ns | netbios-ds | ipv6 | all-other-mc | all-other-bc}

end

dhcp-starvation helps prevent clients from depleting the DHCP address pool by making multiple requests. arp-poison helps prevent clients from spoofing ARP messages.

Because of all these specific multicast and broadcast packet types, the two options all-other-mc and allother-bc help suppress multicast (mc) and broadcast (bc) packets that are not covered by any of the specific options.

Multicast to unicast conversion

Multicast data such as streaming audio or video are sent at a low data rate in WiFi networks. This causes them to occupy considerable air time. FortiOS provides a multicast enhancement option that converts multicast streams to unicast. A unicast stream is sent to each client at high data rate that makes more efficient use of air time. You can configure multicast-to-unicast conversion in the CLI:

config wireless-controller vap edit <vap_name> set multicast-enhance enable

end

Ignore weak or distant clients

Clients beyond the intended coverage area can have some impact on your high-density network. Your APs will respond to these clients’ probe signals, consuming valuable air time. You can configure your WiFi network to ignore weak signals that most likely come from beyond the intended coverage area. The settings are available in the CLI:

config wireless-controller vap edit <vap_name> set probe-resp-suppression enable set probe-resp-threshold <level_int>

end vap_name is the SSID name.

probe-resp-threshold is the signal strength in dBm below which the client is ignored. The range is -95 to 20dBm. The default level is -80dBm.

Turn off 802.11b protocol

By disabling support for the obsolete 802.11b protocol, you can reduce the air time that beacons and management frames occupy. These signals will now be sent at a minimum of 6Mbps, instead of 1Mbps. You can set this for each radio in the FortiAP profile, using the CLI:

config wireless-controller wtp-profile edit <name_string>

 

Disable low data rates                                                                                   Features for high-density deployments

config radio-1 set powersave-optimize no-11b-rate

end

Disable low data rates

Each of the 802.11 protocols supports several data rates. By disabling the lowest rates, air time is conserved, allowing the channel to serve more users. You can set the available rates for each 802.11 protocol: a, b, g, n, ac. Data rates set as Basic are mandatory for clients to support. Other specified rates are supported.

The 802.11 a, b, and g protocols are specified by data rate. 802.11a can support 6,9,12, 18, 24, 36, 48, and 54

Mb/s. 802.11b/g can support 1, 2, 5.5, 6, 9,12, 18, 24, 36, 48, 54 Mb/s. Basic rates are specified with the suffix “basic”, “12-basic” for example. The capabilities of expected client devices need to be considered when deciding the lowest Basic rate.

The 802.11n and ac protocols are specified by the Modulation and Coding Scheme (MCS) Index and the number of spatial streams.

• 11n with 1 or 2 spatial streams can support mcs0/1, mcs1/1, mcs2/1, mcs3/1, mcs4/1, mcs5/1, mcs6/1, mcs7/1,mcs8/2,mcs9/2, mcs10/2, mcs11/2, mcs12/2, mcs13/2, mcs14/2, mcs15/2.
• 11n with 3 or 4 spatial streams can support mcs16/3, mcs17/3, mcs18/3, mcs19/3, mcs20/3, mcs21/3, mcs22/3, mcs23/3, mcs24/4, mcs25/4, mcs26/4, mcs27/4, mcs28/4, mcs29/4, mcs30/4, mcs31/4.
• 11ac with 1 or 2 spatial streams can support mcs0/1, mcs1/1, mcs2/1, mcs3/1, mcs4/1, mcs5/1, mcs6/1, mcs7/1, mcs8/1, mcs9/1, mcs0/2, mcs1/2, mcs2/2, mcs3/2, mcs4/2, mcs5/2, mcs6/2, mcs7/2, mcs8/2, mcs9/2.
• 11ac with 3 or 4 spatial streams can support mcs0/3, mcs1/3, mcs2/3, mcs3/3, mcs4/3, mcs5/3, mcs6/3, mcs7/3, mcs8/3, mcs9/3, mcs0/4, mcs1/4, mcs2/4, mcs3/4, mcs4/4, mcs5/4, mcs6/4, mcs7/4, mcs8/4, mcs9/4 Here are some examples of setting basic and supported rates.

config wireless-controller vap edit <vap_name> set rates-11a 12-basic 18 24 36 48 54 set rates-11bg 12-basic 18 24 36 48 54

set rates-11n-ss34 mcs16/3 mcs18/3 mcs20/3 mcs21/3 mcs22/3 mcs23/3 mcs24/4 mcs25/4 set rates-11ac-ss34 mcs0/3 mcs1/3 mcs2/3 mcs9/4 mcs9/3

end

Limit power

High-density deployments usually cover a small area that has many clients. Maximum AP signal power is usually not required. Reducing the power reduces interference between APs. Fortinet recommends that you use FortiAP automatic power control. You can set this in the FortiAP profile.

1. Go to WiFi & Switch Controller > FortiAP Profiles and edit the profile for your AP model.
2. For each radio, enable Auto TX Power Control and set the TX Power Low and TX Power High The default range of 10 to 17dBm is recommended.

Features for high-density deployments                                                                Use frequency band load-balancing

Use frequency band load-balancing

In a high-density environment is important to make the best use of the two WiFi bands, 2.4GHz and 5GHz. The 5GHz band has more non-overlapping channels and receives less interference from non-WiFi devices, but not all devices support it. Clients that are capable of 5GHz operation should be encouraged to use 5GHz rather than the 2.4GHz band.

To load-balance the WiFi bands, you enable Frequency Handoff in the FortiAP profile. In the FortiGate webbased manager, go to WiFi & Switch Controller > FortiAP Profiles and edit the relevant profile. Or, you can use the CLI:

config wireless-controller wtp-profile edit FAP221C-default config radio-1 set frequency-handoff enable

end

The FortiGate wireless controller continuously performs a scan of all clients in the area and records their signal strength (RSSI) on each band. When Frequency Handoff is enabled, the AP does not reply to clients on the

2.4GHz band that have sufficient signal strength on the 5GHz band. These clients can associate only on the 5GHz band. Devices that support only 2.4GHz receive replies and associate with the AP on the 2.4GHz band.

Setting the handoff RSSI threshold

The FortiAP applies load balancing to a client only if the client has a sufficient signal level on 5GHz. The minimum signal strength threshold is set in the FortiAP profile, but is accessible only through the CLI:

config wireless-controller wtp-profile edit FAP221C-default set handoff-rssi 25

end

handoff-rssi has a range of 20 to 30. RSSI is a relative measure. The higher the number, the stronger the signal.

AP load balancing

The performance of an AP is degraded if it attempts to serve too many clients. In high-density environments, multiple access points are deployed with some overlap in their coverage areas. The WiFi controller can manage the association of new clients with APs to prevent overloading.

To load-balance between APs, enable AP Handoff in the FortiAP profile. In the FortiGate web-based manager, go to WiFi & Switch Controller > FortiAP Profiles and edit the relevant profile. Or, you can use the CLI:

config wireless-controller wtp-profile edit FAP221C-default config radio-1 set ap-handoff enable

end

When an AP exceeds the threshold (the default is 30 clients), the overloaded AP does not reply to a new client that has a sufficient signal at another AP.

Application rate-limiting                                                                                 Features for high-density deployments

Setting the AP load balance threshold

The thresholds for AP handoff are set in the FortiAP profile, but is accessible only through the CLI:

config wireless-controller wtp-profile edit FAP221C-default set handoff-sta-thresh 30 set handoff-rssi 25

end

handoff-sta-thresh sets the number of clients at which AP load balancing begins. It has a range of 5 to 35.

handoff-rssi Sets the minimum signal strength that a new client must have at an alternate AP for the overloaded AP to ignore the client. It has a range of 20 to 30. RSSI is a relative measure. The higher the number, the stronger the signal.

Application rate-limiting

To prevent particular application types from consuming too much bandwidth, you can use the FortiOS Application Control feature.

1. Go to Security Profiles > Application Control.

You can use the default profile or create a new one.

2. Click the category, select Traffic Shaping and then select the priority for the category.

Repeat for each category to be controlled.

3. Select Apply.
4. Go to Policy & Objects > IPv4 Policy and edit your WiFi security policy.
5. In Security Profiles, set Application Control ON and select the security profile that you edited.
6. Select OK.

 

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