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CAPWAP
Cisco lightweight access points use the IETF standard Control and Provisioning of Wireless Access Points Protocol (CAPWAP) to communicate with the controller and other lightweight access points on the network.
CAPWAP, which is based on LWAPP, is a standard, interoperable protocol that enables a controller to manage a collection of wireless access points. CAPWAP is implemented in controller for these reasons:
To provide an upgrade path from Cisco products that use LWAPP to next-generation Cisco products that use CAPWAP
To enable controllers to interoperate with third-party access points in the future
LWAPP-enabled access points can discover and join a CAPWAP controller, and conversion to a CAPWAP controller is seamless. For example, the controller discovery process and the firmware downloading process when using CAPWAP are the same as when using LWAPP. The one exception is for Layer 2 deployments, which are not supported by CAPWAP.
You can deploy CAPWAP controllers and LWAPP controllers on the same network. The CAPWAP-enabled software allows access points to join either a controller running CAPWAP or LWAPP. The only exceptions are that the Cisco Aironet 1040, 1140, 1260, 3500, and 3600 Series Access Points, which support only CAPWAP and join only controllers that run CAPWAP. For example, an 1130 series access point can join a controller running either CAPWAP or LWAPP where an1140 series access point can join only a controller that runs CAPWAP.
If your firewall is currently configured to allow traffic only from access points using LWAPP, you must change the rules of the firewall to allow traffic from access points using CAPWAP.
Ensure that the CAPWAP UDP ports 5246 and 5247 (similar to the LWAPP UDP ports 12222 and 12223) are enabled and are not blocked by an intermediate device that could prevent an access point from joining the controller.
If access control lists (ACLs) are in the control path between the controller and its access points, you need to open new protocol ports to prevent access points from being stranded.
On virtual controller platforms, per-client downstream rate limiting is not supported in FlexConnect central switching.
Rate-limiting is applicable to all traffic destined to the CPU from either direction (wireless or wired). We recommend that you always run the controller with the default config advanced rate enable command in effect to rate limit traffic to the controller and protect against denial-of-service (DoS) attacks. You can use the config advanced rate disable command to stop rate-limiting of Internet Control Message Protocol (ICMP) echo responses for testing purposes. However, we recommend that you reapply the config advanced rate enable command after testing is complete.
Ensure that the controllers are configured with the correct date and time. If the date and time configured on the controller precedes the creation and installation date of certificates on the access points, the access point fails to join the controller.
See the maximum transmission unit (MTU) for the CAPWAP path on the controller by entering this command:
show ap config general Cisco_AP
The MTU specifies the maximum size of any packet (in bytes) in a transmission.
Information similar to the following appears:
Cisco AP Identifier.............................. 9 Cisco AP Name.................................... Maria-1250 Country code..................................... US - United States Regulatory Domain allowed by Country............. 802.11bg:-A 802.11a:-A AP Country code.................................. US - United States AP Regulatory Domain............................. 802.11bg:-A 802.11a:-A Switch Port Number .............................. 1 MAC Address...................................... 00:1f:ca:bd:bc:7c IP Address Configuration......................... DHCP IP Address....................................... 1.100.163.193 IP NetMask....................................... 255.255.255.0 CAPWAP Path MTU.................................. 1485
Use these commands to obtain CAPWAP debug information:
debug capwap events {enable | disable}—Enables or disables debugging of CAPWAP events.
debug capwap errors {enable | disable}—Enables or disables debugging of CAPWAP errors.
debug capwap detail {enable | disable}—Enables or disables debugging of CAPWAP details.
debug capwap info {enable | disable}—Enables or disables debugging of CAPWAP information.
debug capwap packet {enable | disable}—Enables or disables debugging of CAPWAP packets.
debug capwap payload {enable | disable}—Enables or disables debugging of CAPWAP payloads.
debug capwap hexdump {enable | disable}—Enables or disables debugging of the CAPWAP hexadecimal dump.
debug capwap dtls-keepalive {enable | disable}—Enables or disables debugging of CAPWAP DTLS data keepalive packets.
Preferred Mode
Prefer-mode allows an administrator to configure CAPWAP L3 transport (IPv4 and IPv6) through which access points join the WLC (based on its primary/secondary/tertiary configuration).
The following preferred mode configurations are available:
AP-Group specific prefer-mode is pushed to an AP only when the prefer-mode of AP-Group is configured and the AP belongs to that group.
Global prefer-mode is pushed to default-group APs and to those AP-Groups on which the prefer-mode is not configured.
By-default, values of prefer-mode for AP-Group and Global is set to un-configured and IPv4 respectively.
If an AP, with an configured prefer-mode, tries to join the controller and fails, then it will fall back to choose AP-manager of the other transport and joins the same controller. When both transports fail, AP will move to next discovery response.
In such a scenario, Static IP configuration will take precedence over prefer mode. For example:
The controllers CLI provides an XML support of prefer-mode.
Step 1 | Use this command to configure prefer-mode of AP-Group and all APs. Global prefer-mode will not be applied on APs whose AP-Group prefer-mode is already configured. On successful configuration, the AP will restart CAPWAP and join with the configured prefer-mode after choosing a controller based on its primary/secondary/tertiary configuration. config ap preferred-mode {IPv4|IPv6}{ <apgroup>|<all>} | ||
Step 2 | Use this command
to disable (un-configure) the prefer-mode on the AP.
config ap preferred-mode disable
<apgroup>
| ||
Step 3 | Use this command to view the statistics for prefer-mode configuration. The statistics are not cumulative but will be updated for last executed configuration CLI of prefer-mode. show ap prefer-mode stats | ||
Step 4 | Use this command to view the prefer-mode configured for all AP-Groups. show wlan apgroups | ||
Step 5 | Use this command to view the global prefer-mode configured. show network summary | ||
Step 6 | Use this command
to view to check if the prefer mode command is pushed to an AP from global
configuration or from an AP-Group specific configuration.
show ap config general <Cisco AP>
(Cisco Controller) >show ap config general AP-3702E Cisco AP Identifier.............................. 2 Cisco AP Name.................................... AP-3702E Country code..................................... US - United States Regulatory Domain allowed by Country............. 802.11bg:-A 802.11a:-A AP Country code.................................. US - United States AP Regulatory Domain............................. 802.11bg:-A 802.11a:-A Switch Port Number .............................. 1 MAC Address...................................... bc:16:65:09:4e:fc IPv6 Address Configuration....................... SLAAC IPv6 Address..................................... 2001:9:2:35:be16:65ff:fe09:4efc IPv6 Prefix Length............................... 64 Gateway IPv6 Addr................................ fe80::a2cf:5bff:fe51:c4ce NAT External IP Address.......................... None CAPWAP Path MTU.................................. 1473 Telnet State..................................... Globally Enabled Ssh State........................................ Globally Enabled Cisco AP Location................................ default location Cisco AP Floor Label............................. 0 Cisco AP Group Name.............................. default-group Primary Cisco Switch Name........................ amb Primary Cisco Switch IP Address.................. 9.2.35.25 ..................................... ..................................... ..................................... ..................................... ..................................... Ethernet Port Speed.............................. Auto AP Link Latency.................................. Disabled Rogue Detection.................................. Enabled AP TCP MSS Adjust................................ Disabled IPv6 Capwap UDP Lite............................. Enabled Capwap Prefer Mode............................... Ipv6 (Global Config) Hotspot Venue Group.............................. Unspecified Hotspot Venue Type............................... Unspecified DNS server IP ............................. Not Available
|
UDP Lite
The CAPWAP functionality, in Release 8.0, spans both IPv4 and IPv6. CAPWAP changes span the Controller and the AP. An AP running older image, that is not IPv6 capable, can join an IPv6 capable controller provided it has an IPv4 address and download image and vice-versa.
Implementation of IPv6 mandates complete payload checksum for User Datagram Protocol (UDP) which slows down the performance of the AP and the Controller. To minimize the performance impact, Controller and AP supports UDP Lite that mandates only a header checksum of the datagram, thereby avoiding checksum on the entire packet. Enabling UDP Lite enhances the packet processing time.
UDP Lite protocol uses the IP Protocol ID 136 and uses the same CAPWAP port as used by UDP. Enabling UDP Lite would require the network firewall to allow protocol 136. Switching between UDP and UDP Lite causes the AP to disjoin and rejoin. UDP Lite is used for data traffic and UDP for control traffic.
A controller with UDP Lite enabled on it can exchange messages with IPv6 enabled APs along with the existing APs that support only IPv4.
Note | A dual stack controller responds to a discovery request with both the IPv4 and IPv6 AP Managers. |
AP Discovery mechanism uses both, IPv4 and IPv6 addresses assigned to an AP. An AP will use the source address selection to determine the address to use to reach an IPv6 controller.
Step 1 | Choose to open the Global Configuration page. | ||
Step 2 | Under the
Global UDP Lite section, select the
UDP Lite checkbox to enable UDP Lite globally.
| ||
Step 3 | Click Apply to set the global UDP Lite configuration. | ||
Step 4 | If desired, you can choose
to override the global UDP Lite configuration by unselecting the Global IPv6
UDP Lite mentioned in Step 2.
| ||
Step 5 | Click Save Configuration to save your changes. |
Step 1 | Choose to open the All APs page. | ||
Step 2 | Select an AP Name with an IPv6 address and click on it to open the Details page of the selected AP. | ||
Step 3 | Under the
Advanced
tab, select the
UDP Lite
checkbox to enable UDP Lite for the selected AP.
| ||
Step 4 | Click Apply to commit your changes. | ||
Step 5 | Click Save Configuration to save your changes. |
Step 1 | Use this command to enable UDP Lite globally. config ipv6 capwap udplite enable all |
Step 2 | Use this command to enable UDP Lite on a selected AP. config ipv6 capwap udplite enable <Cisco AP> |
Step 3 | Use this command to disable UDP Lite globally. config ipv6 capwap udplite disable all |
Step 4 | Use this command to disable UDP Lite on a selected AP. config ipv6 capwap udplite disable <Cisco AP> |
Step 5 | Use this command to view the status of UDP Lite on a controller.
show ipv6 summary
(Cisco Controller) >show ipv6 summary Global Config............................... Disabled Reachable-lifetime value.................... 300 Stale-lifetime value........................ 86400 Down-lifetime value......................... 30 RA Throttling............................... Disabled RA Throttling allow at-least................ 1 RA Throttling allow at-most................. 1 RA Throttling max-through................... 10 RA Throttling throttle-period............... 600 RA Throttling interval-option............... passthrough NS Mulitcast CacheMiss Forwarding........... Disabled NA Mulitcast Forwarding..................... Enabled IPv6 Capwap UDP Lite........................ Enabled Operating System IPv6 state ................ Disabled (Cisco Controller) > |
Data DTLS
Cisco WLCs enable you to encrypt CAPWAP control packets (and optionally, CAPWAP data packets) that are sent between the AP and the Cisco WLC using Datagram Transport Layer Security (DTLS). DTLS is a standards-track Internet Engineering Task Force (IETF) protocol based on TLS. CAPWAP control packets are management packets exchanged between a controller and an access point while CAPWAP data packets encapsulate forwarded wireless frames. CAPWAP control and data packets are sent over separate UDP ports: 5246 (control) and 5247 (data). If an access point does not support DTLS data encryption, DTLS is enabled only for the control plane, and a DTLS session for the data plane is not established.
Release |
Support Information |
---|---|
8.2 |
Not supported |
8.3.11x.0 or a later release |
Supported in Cisco WLC and Cisco Wave 2 AP |
Any release |
Not supported in Cisco Wave 1 AP |
The following are supported for web authentication and WebAdmin based on the configuration:
Note | Cisco WLC supports only static configuration of gateway. Therefore, the ICMP redirect to change IP address of the gateway is not considered. |
Cisco 1130 and 1240 series access points support DTLS data encryption with software-based encryption.
Cisco 1040, 1140, 1250, 1260, 1550, 1600, 1700, 2600, 2700, 3500, 3600, 3700 series access points support DTLS data encryption with hardware-based encryption
Cisco Aironet 1552 and 1522 outdoor access points support data DTLS.
DTLS data encryption is not supported on Cisco Aironet 700, 800, and 1530 Series Access Points.
DTLS data encryption is enabled automatically for OfficeExtend access points but disabled by default for all other access points. Most access points are deployed in a secure network within a company building, so data encryption is not necessary. In contrast, the traffic between an OfficeExtend access point and the controller travels through an unsecure public network, so data encryption is more important for these access points. When data encryption is enabled, traffic is encrypted at the access point before it is sent to the controller and at the controller before it is sent to the client.
Encryption limits throughput at both the controller and the access point, and maximum throughput is desired for most enterprise networks.
In a Cisco unified local wireless network environment, do not enable DTLS on the Cisco 1130 and 1240 access points, as it may result in severe throughput degradation and may render the APs unusable.
See the OfficeExtend Access Points section for more information on OfficeExtend access points.
You can use the controller to enable or disable DTLS data encryption for a specific access point or for all access points.
The availability of data DTLS is as follows:
The Cisco 5508 WLC will be available with two licenses options: One that allows data DTLS without any license requirements and another image that requires a license to use data DTLS. See the Upgrading or Downgrading DTLS Images for Cisco 5500 Series Controllers section. The images for the DTLS and licensed DTLS images are as follows:
Cisco 2504 WLC, Cisco WiSM2, Cisco Virtual Wireless Controllers—By default do not contain DTLS. To turn on data DTLS, you must install a license. These platforms have a single image with data DTLS turned off. To use data DTLS you must have a license.
For Cisco Virtual Wireless Controllers without Data DTLS, the average controller throughput is about 200 Mbps. With all APs using Data DTLS, the average controller throughput is about 100 Mbps.
If your controller does not have a data DTLS license and if the access point associated with the controller has DTLS enabled, the data path will be unencrypted.
Non-Russian customers using Cisco 5508 Series Controller do not need data DTLS license. However all customers using Cisco 2504 WLCs, Cisco 8510 WLCS, Cisco WiSM2, and Cisco Virtual Wireless Controllers need a data DTLS license to turn on the Data DTLS feature.
You cannot install a regular image (nonlicensed data DTLS) once a licensed data DTLS image is installed.
You can upgrade from one licensed DTLS image to another licensed DTLS image.
You can upgrade from a regular image (DTLS) to a licensed DTLS image in a two step process.
You can use the show sysinfo command to verify the LDPE image, before and after the image upgrade.
Ensure that the base license is installed on the Cisco WLC. Once the license is installed, you can enable data encryption for the access points.
Step 1 | Choose to open the All APs page. | ||
Step 2 | Click the name of the AP for which you want to enable data encryption. | ||
Step 3 | Choose the Advanced tab to open the All APs > Details for (Advanced) page. | ||
Step 4 | Check the Data Encryption check box to enable data encryption for this access point or unselect it to disable this feature. The default value is unselected.
| ||
Step 5 | Save the configuration. |
Note | In images without a DTLS license, the config or show commands are not available. |
To enable DTLS data encryption for access points on the controller using the controller CLI, follow these steps:
Step 1 | Enable or disable data
encryption for all access points or a specific access point by entering this
command:
config ap link-encryption {enable | disable} {all | Cisco_AP} The default value is disabled.
| ||
Step 2 | When prompted to confirm that you want to disconnect the access point(s) and attached client(s), enter Y. | ||
Step 3 | Enter the save config command to save your configuration. | ||
Step 4 | See the encryption state of
all access points or a specific access point by entering this command:
show ap link-encryption {all | Cisco_AP} This command also shows authentication errors, which tracks the number of integrity check failures, and replay errors, which tracks the number of times that the access point receives the same packet. | ||
Step 5 | See a summary of all active
DTLS connections by entering this command:
| ||
Step 6 | Enable new cipher suites for
DTLS connection between AP and controller by entering this command:
config ap dtls-cipher-suite {RSA-AES256-SHA256 | RSA-AES256-SHA | RSA-AES128-SHA} | ||
Step 7 | See the summary of DTLS cipher
suite by entering this command:
show ap dtls-cipher-suite |
Configuring VLAN Tagging for CAPWAP Frames from Access Points
You can configure VLAN tagging on the Ethernet interface either directly on the AP console or through the controller. The configuration is saved in the flash memory and all CAPWAP frames use the VLAN tag as configured, along with all the locally switched traffic, which is not mapped to a VLAN.
This feature is not supported on mesh access points that are in bridge mode.
CAPWAP VLAN tagging is not supported on these 802.11ac Wave 2 APs: 18xx, 2800, 3800, and 1560.
Step 1 | Choose to open the All APs page. |
Step 2 | Click the AP name from the list of AP names to open the Details page for the AP. |
Step 3 | Click the Advanced tab. |
Step 4 | In the VLAN Tagging area, select the VLAN Tagging check box. |
Step 5 | In the Trunk VLAN ID text box, enter an ID. If the access point is unable to route traffic through the specified trunk VLAN after about 10 minutes, the access point performs a recovery procedure by rebooting and sending CAPWAP frames in untagged mode to try and reassociate with the controller. The controller sends a trap to a trap server such as the Cisco Prime Infrastructure, which indicates the failure of the trunk VLAN. If the access point is unable to route traffic through the specified trunk VLAN, it untags the packets and reassociates with the controller. The controller sends a trap to a trap server such as the Cisco Prime Infrastructure, which indicates the failure of the trunk VLAN. If the trunk VLAN ID is 0, the access point untags the CAPWAP frames. The VLAN Tag status is displayed showing whether the AP tags or untags the CAPWAP frames. |
Step 6 | Click Apply. |
Step 7 | You are prompted with a warning message saying that the configuration will result in a reboot of the access point. Click OK to continue. |
Step 8 | Click Save Configuration. |
After the configuration, the switch or other equipment connected to the Ethernet interface of the AP must also be configured to support tagged Ethernet frames.
Discovering and Joining Cisco WLC
In a CAPWAP environment, a lightweight access point discovers a controller by using CAPWAP discovery mechanisms and then sends the controller a CAPWAP join request. The controller sends the access point a CAPWAP join response allowing the access point to join the controller. When the access point joins the controller, the controller manages its configuration, firmware, control transactions, and data transactions.
Upgrade and downgrade paths from LWAPP to CAPWAP or from CAPWAP to LWAPP are supported. An access point with an LWAPP image starts the discovery process in LWAPP. If it finds an LWAPP controller, it starts the LWAPP discovery process to join the controller. If it does not find a LWAPP controller, it starts the discovery in CAPWAP. If the number of times that the discovery process starts with one discovery type (CAPWAP or LWAPP) exceeds the maximum discovery count and the access point does not receive a discovery response, the discovery type changes to the other type. For example, if the access point does not discover the controller in LWAPP, it starts the discovery process in CAPWAP.
If an access point is in the UP state and its IP address changes, the access point tears down the existing CAPWAP tunnel and rejoins the controller.
To configure the IP addresses that the controller sends in its CAPWAP discovery responses, use the config network ap-discovery nat-ip-only {enable | disable} command.
Layer 3 CAPWAP or LWAPP discovery—This feature can be enabled on different subnets from the access point and uses either IPv4 or IPv6 addresses and UDP packets rather the MAC addresses used by Layer 2 discovery.
CAPWAP Multicast Discovery—Broadcast does not exist in IPv6 address. Access point sends CAPWAP discovery message to all the controllers multicast address (FF01::18C). The controller receives the IPv6 discovery request from the AP only if it is in the same L2 segment and sends back the IPv6 discovery response.
Locally stored controller IPv4 or IPv6 address discovery—If the access point was previously associated to a controller, the IPv4 or IPv6 addresses of the primary, secondary, and tertiary controllers are stored in the access point’s nonvolatile memory. This process of storing controller IPv4 or IPv6 addresses on an access point for later deployment is called priming the access point.
DHCP server discovery using option 43—This feature uses DHCP option 43 to provide controller IPv4 addresses to the access points. Cisco switches support a DHCP server option that is typically used for this capability. For more information about DHCP option 43, see the “Using DHCP Option 43 and DHCP Option 60” section.
DHCP server discovery using option 52 —This feature uses DHCP option 52 to allow the AP to discover the IPv6 address of the controller to which it connects. As part of the DHCPv6 messages, the DHCP server provides the controllers management with an IPv6 address.
DNS discovery—The access point can discover controllers through your domain name server (DNS). You must configure your DNS to return controller IPv4 and IPv6 addresses in response to CISCO-LWAPP-CONTROLLER.localdomain or CISCO-CAPWAP-CONTROLLER.localdomain, where localdomain is the access point domain name.
When an access point receives an IPv4/IPv6 address and DNSv4/DNSv6 information from a DHCPv4/DHCPv6 server, it contacts the DNS to resolve CISCO-LWAPP-CONTROLLER.localdomain or CISCO-CAPWAP-CONTROLLER.localdomain. When the DNS sends a list of controller IP addresses, which may include either IPv4 addresses or IPv6 addresses or both the addresses, the access point sends discovery requests to the controllers.
During the discovery process, the 1040, 1140, 1260, 3500, and 3600 series access points will only query for Cisco CAPWAP Controllers. It will not query for LWAPP controllers. If you want these access points to query for both LWAPP and CAPWAP controllers then you need to update the DNS.
Ensure that the controller is set to the current time. If the controller is set to a time that has already occurred, the access point might not join the controller because its certificate may not be valid for that time.
To avoid downtime restart CAPWAP on AP while configuring Global HA, so that AP goes back and joins the backup primary controller. This starts a discovery with the primary controller in the back ground. If the discovery with primary is successful, it goes back and joins the primary again.
Cisco Aironet access points use the type-length-value (TLV) format for DHCP option 43. DHCP servers must be programmed to return the option based on the access point’s DHCP Vendor Class Identifier (VCI) string (DHCP option 60).
The format of the TLV block is as follows:
See the product documentation for your DHCP server for instructions on configuring DHCP option 43. The Upgrading Autonomous Cisco Aironet Access Points to Lightweight Mode document contains example steps for configuring option 43 on a DHCP server.
If the access point is ordered with the Service Provider Option - AIR-OPT60-DHCP selected, the VCI string for that access point will be different than those listed above. The VCI string will have the “ServiceProvider”. For example, a 3600 with this option will return this VCI string: "Cisco AP c3600-ServiceProvider".
Note | The controller IP address that you obtain from the DHCP server should be a unicast IP address. Do not configure the controller IP address as a multicast address when configuring DHCP Option 43. |
When replacing a controller, ensure that access points join the new controller.
Step 1 | Configure the new controller as a master controller as follows: |
Step 2 | (Optional) Flush the ARP and MAC address tables within the network infrastructure. |
Step 3 | Restart the access points. |
Step 4 | Once all the access points have joined the new controller, configure the controller not to be a master controller by unselecting the Master Controller Mode check box on the Master Controller Configuration page. |
Step 1 | Configure the new controller as a master controller by entering this command: config network master-base enable |
Step 2 | (Optional) Flush the ARP and MAC address tables within the network infrastructure. |
Step 3 | Restart the access points. |
Step 4 | Configure the controller not to be a master controller after all the access points have joined the new controller by entering this command: |
Backup Cisco WLCs
A single controller at a centralized location can act as a backup for access points when they lose connectivity with the primary controller in the local region. Centralized and regional controllers do not need to be in the same mobility group. You can specify a primary, secondary, and tertiary controller for specific access points in your network. Using the controller GUI or CLI, you can specify the IP addresses of the backup controllers, which allows the access points to fail over to controllers outside of the mobility group.
You can configure primary and secondary backup controllers (which are used if primary, secondary, or tertiary controllers are not specified or are not responsive) for all access points connected to the controller as well as various timers, including heartbeat timers and discovery request timers. To reduce the controller failure detection time, you can configure the fast heartbeat interval (between the controller and the access point) with a smaller timeout value. When the fast heartbeat timer expires (at every heartbeat interval), the access point determines if any data packets have been received from the controller within the last interval. If no packets have been received, the access point sends a fast echo request to the controller.
The access point maintains a list of backup controllers and periodically sends primary discovery requests to each entry on the list. When the access point receives a new discovery response from a controller, the backup controller list is updated. Any controller that fails to respond to two consecutive primary discovery requests is removed from the list. If the access point’s local controller fails, it chooses an available controller from the backup controller list in this order: primary, secondary, tertiary, primary backup, and secondary backup. The access point waits for a discovery response from the first available controller in the backup list and joins the controller if it receives a response within the time configured for the primary discovery request timer. If the time limit is reached, the access point assumes that the controller cannot be joined and waits for a discovery response from the next available controller in the list.
When an access point's primary controller comes back online, the access point disassociates from the backup controller and reconnects to its primary controller. The access point falls back only to its primary controller and not to any available secondary controller for which it is configured. For example, if an access point is configured with primary, secondary, and tertiary controllers, it fails over to the tertiary controller when the primary and secondary controllers become unresponsive. If the secondary controller comes back online while the primary controller is down, the access point does not fall back to the secondary controller and stays connected to the tertiary controller. The access point waits until the primary controller comes back online to fall back from the tertiary controller to the primary controller. If the tertiary controller fails and the primary controller is still down, the access point then falls back to the available secondary controller.
Step 1 | Choose Wireless > Access Points > Global Configuration to open the Global Configuration page. | ||
Step 2 | From the Local Mode AP Fast Heartbeat Timer State drop-down list, choose Enable to enable the fast heartbeat timer for access points in local mode or choose Disable to disable this timer. The default value is Disable. | ||
Step 3 | If you chose
Enable in
Step 2, enter the Local
Mode AP Fast Heartbeat Timeout text box to configure the fast heartbeat timer
for access points in local mode. Specifying a small heartbeat interval reduces
the amount of time it takes to detect a controller failure.
The range for the AP Fast Heartbeat Timeout value for Cisco Flex 7510/8510/8540 Controllers is 10–15 (inclusive) and is 1–10 (inclusive) for other controllers. The default value for the heartbeat timeout for Cisco Flex 7510/8510/8540 Controllers is 10. The default value for other controllers is 1 second. | ||
Step 4 | From the FlexConnect Mode AP Fast Heartbeat Timer State drop-down list, choose Enable to enable the fast heartbeat timer for FlexConnect access points or choose Disable to disable this timer. The default value is Disable. | ||
Step 5 | If you enable FlexConnect fast
heartbeat, enter the FlexConnect Mode AP Fast Heartbeat Timeout value in the
FlexConnect Mode AP Fast Heartbeat Timeout text box. Specifying a small
heartbeat interval reduces the amount of time it takes to detect a controller
failure.
The range for the FlexConnect Mode AP Fast Heartbeat Timeout value for Cisco Flex 7510/8510/8540 Controllers is 10–15 (inclusive) and is 1–10 for other controllers. The default value for the heartbeat timeout for Cisco Flex 7510/8510/8540 Controllers is 10. The default value for other controllers is 1 second. | ||
Step 6 | In the AP Primary Discovery Timeout text box, a value between 30 and 3600 seconds (inclusive) to configure the access point primary discovery request timer. The default value is 120 seconds. | ||
Step 7 | If you want to specify a primary backup controller for
all access points, enter the IPv4/IPv6 address of the primary backup controller
in the Back-up Primary Controller IP Address (IPv4/IPv6) text box and the name
of the controller in the Back-up Primary Controller Name text box.
| ||
Step 8 | If you want to specify a secondary backup controller
for all access points, enter the IPv4/IPv6 address of the secondary backup
controller in the Back-up Secondary Controller IP Address (IPv4/IPv6) text box
and the name of the controller in the Back-up Secondary Controller Name text
box.
| ||
Step 9 | Click Apply to commit your changes. | ||
Step 10 | Configure primary, secondary,
and tertiary backup controllers for a specific access point as follows:
| ||
Step 11 | Click Save Configuration to save your changes. |
Step 1 | Configure a primary
controller for a specific access point by entering this command:
config ap primary-base controller_name Cisco_AP [controller_ip_address]
| ||||
Step 2 | Configure a secondary
controller for a specific access point by entering this command:
config ap secondary-base controller_name Cisco_AP [controller_ip_address] | ||||
Step 3 | Configure a tertiary
controller for a specific access point by entering this command:
config ap tertiary-base controller_name Cisco_AP [controller_ip_address] | ||||
Step 4 | Configure a primary backup
controller for all access points by entering this command:
config advanced backup-controller primary system name ip_addr
| ||||
Step 5 | Configure a secondary backup
controller for all access points by entering this command:
config advanced backup-controller secondary system name ip_addr
| ||||
Step 6 | Enable or
disable the fast heartbeat timer for local or FlexConnect access points by
entering this command:
config advanced timers ap-fast-heartbeat {local | flexconnect | all} {enable | disable} interval where all is both local and FlexConnect access points, and interval is a value between 10 and 15 seconds for Cisco Flex 7510/8510/8540 controllers, and 1 and 10 seconds for other controllers. Specifying a small heartbeat interval reduces the amount of time that it takes to detect a controller failure. The default value is disabled.Configure the access point heartbeat timer by entering this command: config advanced timers ap-heartbeat-timeout interval where interval is a value between 1 and 30 seconds (inclusive). This value should be at least three times larger than the fast heartbeat timer. The default value is 30 seconds.
| ||||
Step 7 | Configure the access point primary discovery request
timer by entering this command:
config advanced timers ap-primary-discovery-timeout interval where interval is a value between 30 and 3600 seconds. The default value is 120 seconds. | ||||
Step 8 | Configure the access point
discovery timer by entering this command:
config advanced timers ap-discovery-timeout interval where interval is a value between 1 and 10 seconds (inclusive). The default value is 10 seconds. | ||||
Step 9 | Configure the 802.11
authentication response timer by entering this command:
config advanced timers auth-timeout interval where interval is a value between 5 and 600 seconds (inclusive). The default value is 10 seconds. | ||||
Step 10 | Save your changes by entering this command: | ||||
Step 11 | See an access point’s
configuration by entering these commands:
Information similar to the following appears for the show ap config general Cisco_AP command for Primary Cisco Switch IP Address using IPv4: Cisco AP Identifier.............................. 1 Cisco AP Name.................................... AP5 Country code..................................... US - United States Regulatory Domain allowed by Country............. 802.11bg:-AB 802.11a:-AB AP Country code.................................. US - United States AP Regulatory Domain............................. 802.11bg:-A 802.11a:-N Switch Port Number .............................. 1 MAC Address...................................... 00:13:80:60:48:3e IP Address Configuration......................... DHCP IP Address....................................... 1.100.163.133 ... Primary Cisco Switch Name........................ 1-5520 Primary Cisco Switch IP Address.................. 2.2.2.2 Secondary Cisco Switch Name...................... 1-8540 Secondary Cisco Switch IP Address................ 2.2.2.2 Tertiary Cisco Switch Name....................... 2-8540 Tertiary Cisco Switch IP Address................. 1.1.1.4 ... Information similar to the following appears for the show ap config general Cisco_AP command for Primary Cisco Switch IP Address using IPv6: Cisco AP Identifier.............................. 1 Cisco AP Name.................................... AP6 Country code..................................... US - United States Regulatory Domain allowed by Country............. 802.11bg:-A 802.11a:-A AP Country code.................................. US - United States AP Regulatory Domain............................. 802.11bg:-A 802.11a:-A Switch Port Number .............................. 13 MAC Address...................................... 44:2b:03:9a:9d:30 IPv6 Address Configuration....................... DHCPv6 IPv6 Address..................................... 2001:9:5:96:295d:3b2:2db2:9b47 IPv6 Prefix Length............................... 128 Gateway IPv6 Addr................................ fe80::6abd:abff:fe8c:764a NAT External IP Address.......................... None CAPWAP Path MTU.................................. 1473 Telnet State..................................... Globally Disabled Ssh State........................................ Globally Disabled Cisco AP Location................................ _5500 Cisco AP Floor Label............................. 0 Cisco AP Group Name.............................. IPv6-Same_VLAN Primary Cisco Switch Name........................ Maulik_WLC_5500-HA Primary Cisco Switch IP Address.................. 2001:9:5:95::11 Information similar to the following appears for the show advanced backup-controller command when configured using IPv4: AP primary Backup Controller .................... controller1 10.10.10.10 AP secondary Backup Controller ............... 0.0.0.0 Information similar to the following appears for the show advanced backup-controller command when configured using IPv6: AP primary Backup Controller .................... WLC_5500-2 fd09:9:5:94::11 AP secondary Backup Controller .................. vWLC 9.5.92.11 Information similar to the following appears for the show advanced timers command: Authentication Response Timeout (seconds)........ 10 Rogue Entry Timeout (seconds).................... 1300 AP Heart Beat Timeout (seconds).................. 30 AP Discovery Timeout (seconds)................... 10 AP Local mode Fast Heartbeat (seconds)........... 10 (enable) AP flexconnect mode Fast Heartbeat (seconds)........... disable AP Primary Discovery Timeout (seconds)........... 120 |
Failover Priority for APs
Each controller has a defined number of communication ports for access points. When multiple controllers with unused access point ports are deployed on the same network and one controller fails, the dropped access points automatically poll for unused controller ports and associate with them.
The following are some guidelines for configuring failover priority for access points:
You can configure your wireless network so that the backup controller recognizes a join request from a higher-priority access point and if necessary disassociates a lower-priority access point as a means to provide an available port.
Failover priority is not in effect during the regular operation of your wireless network. It takes effect only if there are more association requests after a controller failure than there are available backup controller ports.
You can enable failover priority on your network and assign priorities to the individual access points.
By default, all access points are set to priority level 1, which is the lowest priority level. Therefore, you need to assign a priority level only to those access points that warrant a higher priority.
Step 1 | Choose Wireless > Access Points > Global Configuration to open the Global Configuration page. |
Step 2 | From the Global AP Failover Priority drop-down list, choose Enable to enable access point failover priority or choose Disable to disable this feature and turn off any access point priority assignments. The default value is Disable. |
Step 3 | Click Apply to commit your changes. |
Step 4 | Click Save Configuration to save your changes. |
Step 5 | Choose Wireless > Access Points > All APs to open the All APs page. |
Step 6 | Click the name of the access point for which you want to configure failover priority. |
Step 7 | Choose the High Availability tab. The All APs > Details for (High Availability) page appears. |
Step 8 | From the AP Failover Priority drop-down list, choose one of the following options to specify the priority of the access point: |
Step 9 | Click Apply to commit your changes. |
Step 10 | Click Save Configuration to save your changes. |
Step 1 | Enable or disable access point failover priority by entering this command: |
Step 2 | Specify the priority of an access point by entering this command: config ap priority {1 | 2 | 3 | 4} Cisco_AP where 1 is the lowest priority level and 4 is the highest priority level. The default value is 1. |
Step 3 | Enter the save config command to save your changes. |
Confirm whether access point failover priority is enabled on your network by entering this command:
Information similar to the following appears:
RF-Network Name............................. mrf Web Mode.................................... Enable Secure Web Mode............................. Enable Secure Web Mode Cipher-Option High.......... Disable Secure Shell (ssh).......................... Enable Telnet...................................... Enable Ethernet Multicast Mode..................... Disable Ethernet Broadcast Mode..................... Disable IGMP snooping............................... Disabled IGMP timeout................................ 60 seconds User Idle Timeout........................... 300 seconds ARP Idle Timeout............................ 300 seconds Cisco AP Default Master..................... Disable AP Join Priority......................... Enabled ...
See the failover priority for each access point by entering this command:
Information similar to the following appears:
Number of APs.................................... 2 Global AP User Name.............................. user Global AP Dot1x User Name........................ Not Configured AP Name Slots AP Model Ethernet MAC Location Port Country Priority ------- ----- ------------------ ----------------- --------- ---- ------- ------- ap:1252 2 AIR-LAP1252AG-A-K9 00:1b:d5:13:39:74 hallway 6 1 US 1 ap:1121 1 AIR-LAP1121G-A-K9 00:1b:d5:a9:ad:08 reception 1 US 3
To see the summary of a specific access point, you can specify the access point name. You can also use wildcard searches when filtering for access points.
AP Retransmission Interval and Retry Count
The controller and the APs exchange packets using the CAPWAP reliable transport protocol. For each request, a response is defined. This response is used to acknowledge the receipt of the request message. Response messages are not explicitly acknowledged; therefore, if a response message is not received, the original request message is retransmitted after the retransmit interval. If the request is not acknowledged after a maximum number of retransmissions, the session is closed and the APs reassociate with another controller.
You can configure the retransmission intervals and retry count both at a global as well as a specific access point level. A global configuration applies these configuration parameters to all the access points. That is, the retransmission interval and the retry count are uniform for all access points. Alternatively, when you configure the retransmission level and retry count at a specific access point level, the values are applied to that particular access point. The access point specific configuration has a higher precedence than the global configuration.
Retransmission intervals and the retry count do not apply for mesh access points.
You can configure the retransmission interval and retry count for all APs globally or a specific AP.
You can configure the retransmission interval and retry count for all access points globally or a specific access point.
Configure the retransmission interval and retry count for all access points globally by entering the this command:
config ap retransmit {interval | count} seconds all
The valid range for the interval parameter is between 3 and 8. The valid range for the count parameter is between 2 and 5.
Configure the retransmission interval and retry count for a specific access point, by entering this command:
config ap retransmit {interval | count} seconds Cisco_AP
The valid range for the interval parameter is between 3 and 8. The valid range for the count parameter is between 2 and 5.
See the status of the configured retransmit parameters on all or specific APs by entering this command:
Note | Because retransmit and retry values cannot be set for access points in mesh mode, these values are displayed as N/A (not applicable). |
See the status of the configured retransmit parameters on a specific access point by entering this command:
Authorizing Access Points
The Control and Provisioning of Wireless Access Points protocol (CAPWAP) secures the control communication between the access point and controller by a secure key distribution requiring X.509 certificates on both the access point and controller. CAPWAP relies on provisioning of the X.509 certificates. Cisco Aironet access points shipped before July 18, 2005 do not have a MIC, so these access points create an SSC when upgraded to operate in lightweight mode. Controllers are programmed to accept local SSCs for authentication of specific access points and do not forward those authentication requests to a RADIUS server. This behavior is acceptable and secure.
Virtual controllers use SSC certificates instead of Manufacturing Installed Certificates (MIC) used by physical controllers. You can configure the controller to allow an AP to validate the SSC of the virtual controller. When an AP validates the SSC, the AP checks if the hash key of the virtual controller matches the hash key stored in its flash. If a match is found, the AP associates with the controller. If a match is not found, the validation fails and the AP disconnects from the controller and restarts the discovery process. By default, hash validation is enabled. An AP must have the virtual controller hash key in its flash before associating with the virtual controller. If you disable hash validation of the SSC, the AP bypasses the hash validation and directly moves to the Run state. APs can associate with a physical controller, download the hash keys and then associate with a virtual controller. If the AP is associated with a physical controller and hash validation is disabled, the AP associates with any virtual controller without hash validation. The hash key of the virtual controller can be configured for a mobility group member. This hash key gets pushed to the APs, so that the APs can validate the hash key of the controller.
You can configure controllers to use RADIUS servers to authorize access points using MICs. The controller uses an access point’s MAC address as both the username and password when sending the information to a RADIUS server. For example, if the MAC address of the access point is 000b85229a70, both the username and password used by the controller to authorize the access point are 000b85229a70.
Note | The lack of a strong password by the use of the access point’s MAC address should not be an issue because the controller uses MIC to authenticate the access point prior to authorizing the access point through the RADIUS server. Using MIC provides strong authentication. |
Note | If you use the MAC address as the username and password for access point authentication on a RADIUS AAA server, do not use the same AAA server for client authentication. |
You can use an LSC if you want your own public key infrastructure (PKI) to provide better security, to have control of your certificate authority (CA), and to define policies, restrictions, and usages on the generated certificates.
The LSC CA certificate is installed on access points and controllers. You need to provision the device certificate on the access point. The access point gets a signed X.509 certificate by sending a certRequest to the controller. The controller acts as a CA proxy and receives the certRequest signed by the CA for the access point.
When the CA server is in manual mode and if there is an AP entry in the LSC SCEP table that is pending enrollment, the controller waits for the CA server to send a pending response. If there is no response from the CA server, the controller retries a total of three times to get a response, after which the fallback mode comes into effect where the AP provisioning times out and the AP reboots and comes up with MIC.
LSC on controller does not take password challenge. Therefore, for LSC to work, you must disable password challenge on the CA server.
Step 1 |
Choose to open the Local Significant Certificates (LSC) - General page. | ||||
Step 2 | In the CA Server URL text box, enter the URL to the CA server. You can enter either a domain name or an IP address. | ||||
Step 3 | In the Params text boxes, enter the parameters for the device certificate. [Optional] The key size is a value from 2048 to 4096 (in bits), and the default value is 2048. | ||||
Step 4 | Click Apply to commit your changes. | ||||
Step 5 | To add the CA certificate into the controller’s certificate database, hover your cursor over the blue drop-down arrow for the certificate type and choose Add. | ||||
Step 6 | To add the device certificate into the controller's certificate database, hover your cursor over the blue drop-down arrow for the certificate type and choose Add. | ||||
Step 7 | Select the Enable LSC on Controller check box to enable the LSC on the system. | ||||
Step 8 | Click Apply to commit your changes. | ||||
Step 9 | Choose the AP Provisioning tab to open the Local Significant Certificates (LSC) - AP Provisioning page. | ||||
Step 10 | Select the Enable check box and click Update to provision the LSC on the access point. | ||||
Step 11 | Click Apply to commit your changes. | ||||
Step 12 | When a message appears indicating that the access points will be rebooted, click OK. | ||||
Step 13 | In the Number of Attempts to LSC text box, enter the number of times that the access point attempts to join the controller using an LSC before the access point reverts to the default certificate (MIC or SSC). The range is 0 to 255 (inclusive), and the default value is 3.
| ||||
Step 14 | Enter the access point MAC address in the AP Ethernet MAC Addresses text box and click Add to add access points to the provision list.
| ||||
Step 15 | Click Apply to commit your changes. | ||||
Step 16 | Click Save Configuration to save your changes. |
Step 1 | Configure the URL to the CA server by entering this command:
config certificate lsc ca-server http://url:port/path where url can be either a domain name or IP address.
| ||||
Step 2 | Configure the parameters for the device certificate by entering this command:
config certificate lsc subject-params country state city orgn dept e-mail
| ||||
Step 3 | [Optional] Configure a key size by entering this command:
config certificate lsc other-params keysize The keysize is a value from 2048 to 4096 (in bits), and the default value is 2048. | ||||
Step 4 | Add the LSC CA certificate into the controller’s certificate database by entering this command: | ||||
Step 5 | Add the LSC device certificate into the controller’s certificate database by entering this command:
config certificate lsc device-cert {add | delete} | ||||
Step 6 | Enable LSC on the system by entering this command: | ||||
Step 7 | Provision the LSC on the access point by entering this command: | ||||
Step 8 | Configure the
number of times that the access point attempts to join the controller using an
LSC before the access point reverts to the default certificate (MIC or SSC) by
entering this command:
config certificate lsc ap-provision revert-cert retries where retries is a value from 0 to 255, and the default value is 3.
| ||||
Step 9 | Add access points to the provision list by entering this command:
config certificate lsc ap-provision auth-list add AP_mac_addr
| ||||
Step 10 | See the LSC
summary by entering this command:
Information similar to the following appears: LSC Enabled.......................................... Yes LSC CA-Server........................................ http://10.0.0.1:8080/caserver LSC AP-Provisioning.................................. Yes Provision-List................................... Not Configured LSC Revert Count in AP reboots................... 3 LSC Params: Country.......................................... US State............................................ ca City............................................. ss Orgn............................................. org Dept............................................. dep Email............................................ dep@co.com KeySize.......................................... 2048 LSC Certs: CA Cert.......................................... Not Configured RA Cert....................................... Not Configured | ||||
Step 11 | See details
about the access points that are provisioned using LSC by entering this
command:
show certificate lsc ap-provision Information similar to the following appears: LSC AP-Provisioning........................... Yes Provision-List................................ Present Idx Mac Address --- ------------ 1 00:18:74:c7:c0:90 |
Step 1 | Choose Security > AAA > AP Policies to open the AP Policies page. |
Step 2 | If you want the access point to accept self-signed certificates (SSCs), manufactured-installed certificates (MICs), or local significant certificates (LSCs), select the appropriate check box. |
Step 3 | If you want the access points to be authorized using a AAA RADIUS server, select the Authorize MIC APs against auth-list or AAA check box. |
Step 4 | If you want the access points to be authorized
using an LSC, select the
Authorize LSC APs against auth-list
check box.
Enter the Ethernet MAC address for all APs except when in bridge mode (where you need to enter the radio Mac address). |
Step 5 | Click Apply to commit your changes. |
Step 6 | Follow these steps to add an
access point to the controller’s authorization list:
|
Configure an access point authorization policy by entering this command:
config auth-list ap-policy {authorize-ap {enable | disable} | authorize-lsc-ap {enable | disable}}
Configure an access point to accept manufactured-installed certificates (MICs), self-signed certificates (SSCs), or local significant certificates (LSCs) by entering this command:
config auth-list ap-policy {mic | ssc | lsc {enable | disable}}
Configure the user name to be used in access point authorization requests. config auth-list ap-policy {authorize-ap username {ap_name | ap_mac | both}}
Add an access point to the authorization list by entering this command:
config auth-list add {mic | ssc | lsc} ap_mac [ap_key]
where ap_key is an optional key hash value equal to 20 bytes or 40 digits.
Note | To delete an access point from the authorization list, enter this command: config auth-list delete ap_mac. |
See the access point authorization list by entering this command:
AP 802.1X Supplicant
IEEE 802.1X port-based authentication is configured on a device to prevent unauthorized devices (supplicants) from gaining access to the network. The device can combine the function of an access point, depending on the fixed configuration or installed modules.
You can configure 802.1X authentication between a lightweight access point and a Cisco switch. The switch uses a RADIUS server (Cisco ISE) which uses EAP-FAST with anonymous PAC provisioning to authenticate the supplicant AP device.
You can configure global authentication settings that all access points that are currently associated with the controller and any that associate in the future. You can also override the global authentication settings and assign unique authentication settings for a specific access point.
After the 802.1x authentication is configured on the switch, it allows 802.1x authenticated device traffic only.
There are two modes of authentication models:
Global authentication—authentication setup for all APs
AP Level authentication—authentication setup for a particular AP
The switch by default authenticates one device per port. This limitation is not present in the Cisco Catalyst Switches. The host mode type configured on the switch determines the number and type of endpoints allowed on a port. The host mode options are:
Single host mode-a single IP or MAC address is authenticated on a port. This is set as the default.
Multi-host mode-authenticates the first MAC address and then allows an unlimited number of other MAC addresses. Enable the host mode on the switch ports if connected AP has been configured with local switching mode. It allows the client’s traffic pass the switch port. If you want a secured traffic path, then enable dot1x on the WLAN to protect the client data.
The feature supports AP in local mode, FlexConnect mode, sniffer mode, and monitor mode. It also supports WLAN in central switching and local switching modes.
Note | In FlexConnect mode, ensure that the VLAN support is enabled on the AP the correct native VLAN is configured on it. |
802.1x on AP |
Switch |
Result |
---|---|---|
DISABLED |
ENABLED |
AP does not join the controller |
ENABLED |
DISABLED |
AP joins the controller. After failing to receive EAP responses, fallbacks to non-dot1x CAPWAP discovery automatically |
ENABLED |
ENABLED |
AP joins the controller, post port-Authentication |
In a situation where the credentials on the AP need correction, disable the Switch port Dot1x Authentication, and re-enable the port authentication after updating the credentials.
Always disable the Bridge Protocol Data Unit (BPDU) guard on the switch port connected to the AP. Enabling the BPDU guard is allowed only when the switch puts the port in port fast mode.
Step 1 | Choose to open the Global Configuration page. | ||
Step 2 | Under 802.1x Supplicant Credentials, select the 802.1x Authentication check box. | ||
Step 3 | In the Username text box, enter the username that is to be inherited by all access points that join the controller. | ||
Step 4 | In the Password and Confirm Password text boxes, enter the password that is to be inherited by all access points that join the controller.
| ||
Step 5 | Click Apply to send the global authentication username and password to all access points that are currently joined to the controller and to any that join the controller in the future. | ||
Step 6 | Click Save Configuration to save your changes. | ||
Step 7 | If desired, you can choose to override the global authentication settings and assign a unique username and password to a specific access point as follows: |
Step 1 | Configure the global authentication username and password for all access points currently joined to the controller as well as any access points that join the controller in the future by entering this command: config ap 802.1Xuser add username ap-username
password
ap-password
all
| ||||
Step 2 | (Optional) Override the global authentication settings and assign a unique username and password to a specific access point. To do so, enter this command: config ap 802.1Xuser add username ap-username
password
ap-password
Cisco_AP
The authentication settings that you enter in this command are retained across controller and access point reboots and whenever the access point joins a new controller.
| ||||
Step 3 | Enter the save config command to save your changes. | ||||
Step 4 | (Optional) Disable 802.1X authentication for all access points or for a specific access point by entering this command:
config ap 802.1Xuser disable {all | Cisco_AP}
| ||||
Step 5 | See the authentication settings for all access points that join the controller by entering this command:
Information similar to the following appears: Number of APs.................................... 1 Global AP User Name.............................. globalap Global AP Dot1x User Name........................ globalDot1x | ||||
Step 6 | See the authentication settings for a specific access point by entering this command:
show ap config general Cisco_AP
| ||||
Step 7 | See the authentication status on the AP by entering this command: |
To enable 802.1X authentication on a switch port, on the switch CLI, enter these commands:
Infrastructure MFP
Management frame protection (MFP) provides security for the otherwise unprotected and unencrypted 802.11 management messages passed between access points and clients. MFP provides both infrastructure and client support.
Infrastructure MFP—Protects management frames by detecting adversaries that are invoking denial-of-service attacks, flooding the network with associations and probes, interjecting as rogue access points, and affecting network performance by attacking the QoS and radio measurement frames. Infrastructure MFP is a global setting that provides a quick and effective means to detect and report phishing incidents.
Specifically, infrastructure MFP protects 802.11 session management functions by adding message integrity check information elements (MIC IEs) to the management frames emitted by access points (and not those emitted by clients), which are then validated by other access points in the network. Infrastructure MFP is passive. It can detect and report intrusions but has no means to stop them.
Client MFP—Shields authenticated clients from spoofed frames, preventing many of the common attacks against wireless LANs from becoming effective. Most attacks, such as deauthentication attacks, revert to simply degrading performance by contending with valid clients.
Specifically, client MFP encrypts management frames are sent between access points and CCXv5 clients so that both the access points and clients can take preventative action by dropping spoofed class 3 management frames (that is, management frames passed between an access point and a client that is authenticated and associated). Client MFP leverages the security mechanisms defined by IEEE 802.11i to protect the following types of class 3 unicast management frames: disassociation, deauthentication, and QoS (WMM) action. Client MFP protects a client-access point session from the most common type of denial-of-service attack. It protects class 3 management frames by using the same encryption method used for the session’s data frames. If a frame received by the access point or client fails decryption, it is dropped, and the event is reported to the controller.
To use client MFP, clients must support CCXv5 MFP and must negotiate WPA2 using either TKIP or AES-CCMP. EAP or PSK may be used to obtain the PMK. CCKM and controller mobility management are used to distribute session keys between access points for Layer 2 and Layer 3 fast roaming.
Note | To prevent attacks using broadcast frames, access points supporting CCXv5 will not emit any broadcast class 3 management frames (such as disassociation, deauthentication, or action). CCXv5 clients and access points must discard broadcast class 3 management frames. Client MFP supplements infrastructure MFP rather than replaces it because infrastructure MFP continues to detect and report invalid unicast frames sent to clients that are not client-MFP capable as well as invalid class 1 and 2 management frames. Infrastructure MFP is applied only to management frames that are not protected by client MFP. Infrastructure MFP consists of three main components: |
Management frame protection—The access point protects the management frames it transmits by adding a MIC IE to each frame. Any attempt to copy, alter, or replay the frame invalidates the MIC, causing any receiving access point configured to detect MFP frames to report the discrepancy. MFP is supported for use with Cisco Aironet lightweight access points.
Management frame validation—In infrastructure MFP, the access point validates every management frame that it receives from other access points in the network. It ensures that the MIC IE is present (when the originator is configured to transmit MFP frames) and matches the content of the management frame. If it receives any frame that does not contain a valid MIC IE from a BSSID belonging to an access point that is configured to transmit MFP frames, it reports the discrepancy to the network management system. In order for the timestamps to operate properly, all controllers must be Network Time Protocol (NTP) synchronized.
Event reporting—The access point notifies the controller when it detects an anomaly, and the controller aggregates the received anomaly events and can report the results through SNMP traps to the network management system.
Note | Client MFP uses the same event reporting mechanisms as infrastructure MFP. |
Infrastructure MFP is disabled by default and can be enabled globally. When you upgrade from a previous software release, infrastructure MFP is disabled globally if access point authentication is enabled because the two features are mutually exclusive. Once infrastructure MFP is enabled globally, signature generation (adding MICs to outbound frames) can be disabled for selected WLANs, and validation can be disabled for selected access points.
Client MFP is enabled by default on WLANs that are configured for WPA2. It can be disabled, or it can be made mandatory (in which case, only clients that negotiate MFP are allowed to associate) on selected WLANs.
Lightweight access points support infrastructure MFP in local and monitor modes and in FlexConnect mode when the access point is connected to a controller. They support client MFP in local, FlexConnect, and bridge modes.
Client MFP is supported for use only with CCXv5 clients using WPA2 with TKIP or AES-CCMP.
Non-CCXv5 clients may associate to a WLAN if client MFP is disabled or optional.
Error reports generated on a FlexConnect access point in standalone mode cannot be forwarded to the controller and are dropped.
Step 1 | Choose Security> Wireless Protection Policies > AP Authentication/MFP to open the AP Authentication Policy page. | ||
Step 2 | Enable infrastructure MFP globally for the controller by choosing Management Frame Protection from the Protection Type drop-down list. | ||
Step 3 | Click
Apply to commit your changes.
| ||
Step 4 | Configure client MFP for a
particular WLAN after infrastructure MFP has been enabled globally for the
controller as follows:
| ||
Step 5 | Click Save Configuration to save your settings. |
To see the controller’s current global MFP settings, choose Security > Wireless Protection Policies > Management Frame Protection. The Management Frame Protection Settings page appears.
On this page, you can see the following MFP settings:
The Management Frame Protection field shows if infrastructure MFP is enabled globally for the controller.
The Controller Time Source Valid field indicates whether the controller time is set locally (by manually entering the time) or through an external source (such as the NTP/SNTP server). If the time is set by an external source, the value of this field is “True.” If the time is set locally, the value is “False.” The time source is used for validating the timestamp on management frames between access points of different controllers within a mobility group.
The Client Protection field shows if client MFP is enabled for individual WLANs and whether it is optional or required.
Enable or disable infrastructure MFP globally for the controller by entering this command: config wps mfp infrastructure {enable | disable}
Enable or disable client MFP on a specific WLAN by entering this command:
config wlan mfp client {enable | disable} wlan_id [required ]
If you enable client MFP and use the optional required parameter, clients are allowed to associate only if MFP is negotiated.
See the controller’s current MFP settings by entering this command:
show wps mfp summary
See the current MFP configuration for a particular WLAN by entering this command:
show wlan wlan_id
See whether client MFP is enabled for a specific client by entering this command:
See MFP statistics for the controller by entering this command: show wps mfp statistics
Note | This report contains no data unless an active attack is in progress. This table is cleared every 5 minutes when the data is forwarded to any network management stations. |
Use this command if you experience any problems with MFP:
debug wps mfp ? {enable | disable}
where ? is one of the following:
client—Configures debugging for client MFP messages.
capwap—Configures debugging for MFP messages between the controller and access points.
detail—Configures detailed debugging for MFP messages.
report—Configures debugging for MFP reporting.
mm—Configures debugging for MFP mobility (inter-controller) messages.
Access points can fail to join a controller for many reasons such as a RADIUS authorization is pending, self-signed certificates are not enabled on the controller, the access point and controller’s regulatory domains do not match, and so on.
Controller software release 5.2 or later releases enable you to configure the access points to send all CAPWAP-related errors to a syslog server. You do not need to enable any debug commands on the controller because all of the CAPWAP error messages can be viewed from the syslog server itself.
The state of the access point is not maintained on the controller until it receives a CAPWAP join request from the access point, so it can be difficult to determine why the CAPWAP discovery request from a certain access point was rejected. In order to troubleshoot such joining issues without enabling CAPWAP debug commands on the controller, the controller collects information for all access points that send a discovery message to this controller and maintains information for any access points that have successfully joined this controller.
The controller collects all join-related information for each access point that sends a CAPWAP discovery request to the controller. Collection begins with the first discovery message received from the access point and ends with the last configuration payload sent from the controller to the access point.
You can view join-related information for the following numbers of access points:
When the controller is maintaining join-related information for the maximum number of access points, it does not collect information for any more access points.
If any of these conditions are met and the access point has not yet joined a controller, you can also configure a DHCP server to return a syslog server IP address to the access point using option 7 on the server. The access point then starts sending all syslog messages to this IP address.
Note | The access point joins the controller with a DHCP address from an internal DHCP pool configured on WLC. When the DHCP lease address is deleted in WLC, the access point reloads with the following message: AP Rebooting: Reset Reason - Admin Reload. This is a common behavior in Cisco IOS and Wave 2 APs. |
You can also configure the syslog server IP address through the access point CLI, provided the access point is currently not connected to the controller by entering the capwap ap log-server syslog_server_IP_address command.
When the access point joins a controller for the first time, the controller pushes the global syslog server IP address (the default is 255.255.255.255) to the access point. After that, the access point sends all syslog messages to this IP address, until it is overridden by one of the following scenarios:
The access point is still connected to the same controller, and the global syslog server IP address configuration on the controller has been changed using the config ap syslog host global syslog_server_IP_address command. In this case, the controller pushes the new global syslog server IP address to the access point.
The access point is still connected to the same controller, and a specific syslog server IP address has been configured for the access point on the controller using the config ap syslog host specific Cisco_AP syslog_server_IP_address command. In this case, the controller pushes the new specific syslog server IP address to the access point.
The access point gets disconnected from the controller, and the syslog server IP address has been configured from the access point CLI using the lwapp ap log-server syslog_server_IP_address command. This command works only if the access point is not connected to any controller.
The access point gets disconnected from the controller and joins another controller. In this case, the new controller pushes its global syslog server IP address to the access point.
Whenever a new syslog server IP address overrides the existing syslog server IP address, the old address is erased from persistent storage, and the new address is stored in its place. The access point also starts sending all syslog messages to the new IP address, provided the access point can reach the syslog server IP address.
You can configure the syslog server for access points using the controller GUI and view the access point join information using the controller GUI or CLI.
When the name of the access point is modified using the config ap name new_name old_name command, then the new AP name is updated. You can view the new AP name updated in both the show ap join stats summary all as well as the show ap summary commands.
Note | When an AP in a Release 8.0 image tries to join Cisco WLC, Release 8.3 (having Release 8.2 as the primary image and Release 8.2.1 as the secondary image on Flash), the AP goes into a perpetual loop. (Note that the release numbers are used only as an example to illustrate the scenario of three different images and does not apply to the releases mentioned.) This loop occurs due to version mismatch. After the download, when the AP compares its image with the Cisco WLC image, there will be a version mismatch. The AP will start the entire process again, resulting in a loop. |
Step 1 | Perform one of the following:
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Step 2 | Enter the save config command to save your changes. | ||||||
Step 3 | See the global
syslog server settings for all access points that join the controller by
entering this command:
Information similar to the following appears: AP global system logging host.................... 255.255.255.255 | ||||||
Step 4 | See the syslog server settings for a specific access point by entering this command: |
Join statistics for an access point that sends a CAPWAP discovery request to the controller at least once are maintained on the controller even if the access point is rebooted or disconnected. These statistics are removed only when the controller is rebooted or when you choose to clear the statistics.
Step 1 |
Choose Monitor > Statistics > AP Join to open the AP Join Stats page.
This page lists all of the access points that are joined to the controller or that have tried to join. It shows the radio MAC address, access point name, current join status, Ethernet MAC address, IP address, and last join time for each access point. The total number of access points appears in the upper right-hand corner of the page. If the list of access points spans multiple pages, you can view these pages by clicking the page number links. Each page shows the join statistics for up to 25 access points.
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Step 2 | If you want to search for specific access points in the list of access points on the AP Join Stats page, follow these steps to create a filter to display only access points that meet certain criteria (such as MAC address or access point name).
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Step 3 | To see detailed join statistics for a specific access point, click the radio MAC address of the access point. The AP Join Stats Detail page appears. This page provides information from the controller’s perspective on each phase of the join process and shows any errors that have occurred. |
See the MAC addresses of all the access points that are joined to the controller or that have tried to join by entering this command:
See the last join error detail for a specific access point by entering this command:
show ap join stats summary ap_mac
where ap_mac is the MAC address of the 802.11 radio interface.
Note | To obtain the MAC address of the 802.11 radio interface, enter the show interfaces Dot11Radio 0 command on the access point. Information similar to the following appears: Is the AP currently connected to controller................ Yes Time at which the AP joined this controller last time...... Aug 21 12:50:36.061 Type of error that occurred last........................... AP got or has been disconnected Reason for error that occurred last........................ The AP has been reset by the controller Time at which the last join error occurred.............. Aug 21 12:50:34.374 |
See all join-related statistics collected for a specific access point by entering this command:
show ap join stats detailed ap_mac
Information similar to the following appears:
Discovery phase statistics - Discovery requests received.............................. 2 - Successful discovery responses sent...................... 2 - Unsuccessful discovery request processing................ 0 - Reason for last unsuccessful discovery attempt........... Not applicable - Time at last successful discovery attempt................ Aug 21 12:50:23.335 - Time at last unsuccessful discovery attempt.............. Not applicable Join phase statistics - Join requests received................................... 1 - Successful join responses sent........................... 1 - Unsuccessful join request processing..................... 1 - Reason for last unsuccessful join attempt................ RADIUS authorization is pending for the AP - Time at last successful join attempt..................... Aug 21 12:50:34.481 - Time at last unsuccessful join attempt................... Aug 21 12:50:34.374 Configuration phase statistics - Configuration requests received.......................... 1 - Successful configuration responses sent.................. 1 - Unsuccessful configuration request processing............ 0 - Reason for last unsuccessful configuration attempt....... Not applicable - Time at last successful configuration attempt............ Aug 21 12:50:34.374 - Time at last unsuccessful configuration attempt.......... Not applicable Last AP message decryption failure details - Reason for last message decryption failure............... Not applicable Last AP disconnect details - Reason for last AP connection failure.................... The AP has been reset by the controller Last join error summary - Type of error that occurred last......................... AP got or has been disconnected - Reason for error that occurred last...................... The AP has been reset by the controller - Time at which the last join error occurred............... Aug 21 12:50:34.374
Clear the join statistics for all access points or for a specific access point by entering this command: