คู่มือเริ่มต้นใช้งาน Cisco Aironet 2800 Series Access Points

Access Point Features

The 2800 series access point is a wireless controller-based product and supports:

• Integrated antennas on the 2802I access point model (AIR-AP2802I-x-K9)
• External antennas on the 2802E access point models (AIR-AP2802E-x-K9)

Note The ‘x’ in the model numbers represents the regulatory domain. For information on supported regulatory domains, see the“AP Model Numbers and Regulatory Domains” section.

• Flexible Radio Assignment, allowing for either manual configuration or for the APs to intelligently determine the operating role of the integrated radios based on the available RF environment. The AP can operate in the following modes:

– 2.4 GHz and 5 GHz role, where one radio serves clients in 2.4 GHz mode, while the other serves clients in 5 GHz mode.

– Dual 5 GHz radio role, with both radios operating in the 5 GHz band, actively serving client devices to maximize the benefits of 802.11ac Wave 2 and to increase client device capacity.

– Wireless Security Monitoring and 5 GHz role, where one radio serves 5 GHz clients, while the other radio scans both 2.4 GHz and 5 GHz for wIPS attackers, CleanAir interferers, and rogue devices.

• Multiuser Multiple-Input Multiple-Output (MU-MIMO) technology with 3 spatial streams.
• Cross-AP Noise Reduction, a Cisco innovation that enables APs to intelligently collaborate in real time about RF conditions so that users connect with optimized signal quality and performance.
• Optimized AP Roaming for ensuring that client devices associate with the AP in their coverage range that offers the fastest data rate available.
• Cisco ClientLink 4.0 technology for improved downlink performance to all mobile devices, including one-, two-, and three-spatial-stream devices up to 802.11ac Wave 1 and Wave 2. The technology also improves battery life on mobile devices.
• Cisco CleanAir technology enhanced with 160MHz channel support. CleanAir delivers proactive, high-speed spectrum intelligence across 20-, 40-, and 80-, and 160-MHz-wide channels to combat performance problems arising from wireless interference.
• MIMO equalization capabilities, which optimize uplink performance and reliability by reducing the impact of signal fade.

The AP supports the following operating modes:

• Centralized
• Sniffer
• FlexConnect
• Monitor Mode
• Service Provider Option 60 (DHCP Option 60)

AP Model Numbers and Regulatory Domains

You need to verify whether the AP model you have is approved for use in your country. To verify approval and to identify the regulatory domain that corresponds to a particular country, visithttp://www.cisco.com/go/aironet/compliance. Not all regulatory domains have been approved. As and when they are approved, this compliance list will be updated.

Antennas and Radios

The 2800 series access point contains a dedicated 5 GHz radio and a flexible radio that can be configured as a 2.4 GHz radio (default) or as an additional 5 GHz radio. The 2800 series access point configurations are:

• AIR-AP2802I-x-K9—One 2.4 GHz/5 GHz flexible radio and one 5 GHz radio.
• AIR-AP2802E-x-K9—One 2.4 GHz/5 GHz flexible radio and one 5 GHz radio. The are 4 dual-band dipole and a Smart antenna connector.

Internal Antennas

The 2802I has 12 cross polarized internal antennas.

External Antennas

The 2802E model is configured with up to four external dual-band dipole antennas, and two 2.4 GHz/ 5 GHz dual-band radios. The radio and antennas support frequency bands 2400–2500 MHz and 5180–5865 MHz through a common dual-band RF interface. Features of the external dual-band dipole antennas are:

• Four RTNC antenna connectors on the top of the access point
• Four TX/RX antennas
• Smart Antenna connector for connecting an external antenna

Supported External Antennas

Cisco also provides the following external antenna accessories:

• 5 ft Low Loss RF cable with RP-TNC and N-type Connectors (AIR-CAB005LL-R-N/=). You will need four of these.
• 2 ft Smart Antenna Connector to RP-TNC Connectors (AIR-CAB002-DART-R=).

The Controller Discovery Process

The access point uses standard Control and Provisioning of Wireless Access Points Protocol (CAPWAP) to communicate between the controller and other wireless access points on the network. CAPWAP is a standard, inter-operable protocol which enables an access controller to manage a collection of wireless termination points. The discovery process using CAPWAP is identical to the Lightweight Access Point Protocol (LWAPP) used with previous Cisco Aironet access points. LWAPP-enabled access points are compatible with CAPWAP, and conversion to a CAPWAP controller is seamless. Deployments can combine CAPWAP and LWAPP software on the controllers.

The functionality provided by the controller does not change except for customers who have Layer 2 deployments, which CAPWAP does not support.

In a CAPWAP environment, a wireless access point discovers a controller by using CAPWAP discovery mechanisms and then sends it 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.

Note For additional information about the discovery process and CAPWAP, see the Cisco Wireless LAN Controller Software Configuration Guide. This document is available on Cisco.com.

Note CAPWAP support is provided in controller software release 5.2 or later. However, your controller must be running the release that supports 2800 series access points, as specified in the access point data sheet.

Note You cannot edit or query any access point using the controller CLI if the name of the access point contains a space.

Note Make sure 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.

Access points must be discovered by a controller before they can become an active part of the network. The access point supports these controller discovery processes:

• Layer 3 CAPWAP discovery—Can occur on different subnets than the access point and uses IP addresses and UDP packets rather than MAC addresses used by Layer 2 discovery.
• Locally stored controller IP address discovery—If the access point was previously joined to a controller, the IP addresses of the primary, secondary, and tertiary controllers are stored in the access point non-volatile memory. This process of storing controller IP addresses on an access point for later deployment is called priming the access point. For more information about priming, see the “Performing a Pre-Installation Configuration” section.
• DHCP server discovery—This feature uses DHCP option 43 to provide controller IP 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 “Configuring DHCP Option 43” section.
• DNS discovery—The access point can discover controllers through your domain name server (DNS). For the access point to do so, you must configure your DNS to return controller IP addresses in response to CISCO-CAPWAP-CONTROLLER.localdomain, where localdomain is the access point domain name. Configuring the CISCO-CAPWAP-CONTROLLER provides backwards compatibility in an existing customer deployment. When an access point receives an IP address and DNS information from a DHCP server, it contacts the DNS to resolve CISCO-CAPWAP-CONTROLLER.localdomain. When the DNS sends a list of controller IP addresses, the access point sends discovery requests to the controllers.

Deploying the Access Point on the Wireless Network

After you have mounted the access point, follow these steps to deploy it on the wireless network:

Step 1 Connect and power up the access point.

Step 2 Observe the access point LED (for LED descriptions, see “Checking the Access Point LEDs” section).

a. When you power up the access point, it begins a power-up sequence that you can verify by observing the access point LED. If the power-up sequence is successful, the discovery and join process begins. During this process, the LED blinks sequentially green, red, and off. When the access point has joined a controller, the LED is chirping green if no clients are associated or green if one or more clients are associated.

b. If the LED is not on, the access point is most likely not receiving power.

c. If the LED blinks sequentially for more than 5 minutes, the access point is unable to find its primary, secondary, and tertiary Cisco wireless LAN controller. Check the connection between the access point and the Cisco wireless LAN controller, and be sure the access point and the Cisco wireless LAN controller are either on the same subnet or that the access point has a route back to its primary, secondary, and tertiary Cisco wireless LAN controller. Also, if the access point is not on the same subnet as the Cisco wireless LAN controller, be sure that there is a properly configured DHCP server on the same subnet as the access point. See the“Configuring DHCP Option 43” section for additional information.

Step 3 Reconfigure the Cisco wireless LAN controller so that it is not the Master.

Note A Master Cisco wireless LAN controller should be used only for configuring access points and not in a working network.

Using the Mode Button

Using the Mode button (see Figure 3) you can:

• Reset the AP to the default factory-shipped configuration.
• Clear the AP internal storage, including all configuration files.

To use the mode button, press, and keep pressed, the mode button on the access point during the AP boot cycle. Wait until the AP status LED changes to Amber. During this, the AP console shows a seconds counter, counting the number of seconds the mode button is pressed. Then:

• To reset the AP to the default factory-shipped configuration, keep the mode button pressed for less than 20 seconds. The AP configuration files are cleared.

This resets all configuration settings to factory defaults, including passwords, WEP keys, the IP address, and the SSID.

• To clear the AP internal storage, including all configuration files and the regulatory domain configuration, keep the mode button pressed for more than 20 seconds, but less than 60 seconds.

The AP status LED changes from Amber to Red, and all the files in the AP storage directory are cleared.

If you keep the mode button pressed for more than 60 seconds, the mode button is assumed faulty and no changes are made.

Troubleshooting the Access Point to Cisco Controller Join Process

Note Ensure that your controller is running the latest Cisco Wireless Controller Software Release as specified in the access point data sheet.

Access points can fail to join a controller for many reasons: a RADIUS authorization is pending; self-signed certificates are not enabled on the controller; the access point and the controller regulatory domains don’t match, and so on.

Controller software enables 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. Therefore, it can be difficult to determine why the CAPWAP discovery request from a certain access point was rejected. In order to troubleshoot such joining problems without enabling CAPWAP debug commands on the controller, the controller collects information for all access points that send a discovery message to it and maintains information for any access points that have successfully joined it.

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 up to three times the maximum number of access points supported by the platform for the 2500 series controllers and the Controller Network Module within the Cisco 28/37/28xx Series Integrated Services Routers.

Note The maximum number of access points varies for the Cisco WiSM2, depending on which controller software release is being used.

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.

An access point sends all syslog messages to IP address 255.255.255.255 by default when any of the following conditions are met:

• An access point running software release 8.2.110.0 or later has been newly deployed.
• An existing access point running software release 8.2.110.0 or later has been reset after clearing the configuration.

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.

When the access point joins a controller for the first time, the controller sends 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 sends 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 sends the new specific syslog server IP address to the access point.
• The access point is disconnected from the controller and joins another controller. In this case, the new controller sends 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 and view the access point join information only from the controller CLI.

Important Information for Controller-based Deployments

Keep these guidelines in mind when you use 2802 series access points:

• The access point can only communicate with Cisco wireless LAN controllers.
• The access point does not support Wireless Domain Services (WDS) and cannot communicate with WDS devices. However, the controller provides functionality equivalent to WDS when the access point joins it.
• CAPWAP does not support Layer 2. The access point must get an IP address and discover the controller using Layer 3, DHCP, DNS, or IP subnet broadcast.
• The access point console port is enabled for monitoring and debug purposes. All configuration commands are disabled when the access point is connected to a controller.

Configuring DHCP Option 43

You can use DHCP Option 43 to provide a list of controller IP addresses to the access points, enabling them to find and join a controller.

The following is a DHCP Option 43 configuration example on a Windows 2003 Enterprise DHCP server for use with Cisco Aironet lightweight access points. For other DHCP server implementations, consult product documentation for configuring DHCP Option 43. In Option 43, you should use the IP address of the controller management interface.

Note DHCP Option 43 is limited to one access point type per DHCP pool. You must configure a separate DHCP pool for each access point type.

The 2800 series access point uses the type-length-value (TLV) format for DHCP Option 43. DHCP servers must be programmed to return the option based on the access point DHCP Vendor Class Identifier (VCI) string (DHCP Option 43). The VCI string for the 2800 series access point is:

Cisco AP c2800

The format of the TLV block is listed below:

• Type: 0xf1 (decimal 241)
• Length: Number of controller IP addresses * 4
• Value: List of WLC management interfaces

To configure DHCP Option 43 in the embedded Cisco IOS DHCP server, follow these steps:

Step 1 Enter configuration mode at the Cisco IOS CLI.

Step 2 Create the DHCP pool, including the necessary parameters such as default router and name server. A DHCP scope example is as follows:

Step 3 Add the option 43 line using the following syntax:

The hex string is assembled by concatenating the TLV values shown below:

Type + Length + Value

Type is always f1(hex). Length is the number of controller management IP addresses times 4 in hex. Value is the IP address of the controller listed sequentially in hex.

For example, suppose that there are two controllers with management interface IP addresses, 10.126.126.2 and 10.127.127.2. The type is f1(hex). The length is 2 * 4 = 8 = 08 (hex). The IP addresses translate to 0a7e7e02 and 0a7f7f02. Assembling the string then yields f1080a7e7e020a7f7f02. The resulting Cisco IOS command added to the DHCP scope is option 43 hex f1080a7e7e020a7f7f02.

What is Flexible Radio Assignment?

The Flexible Radio Assignment (FRA) feature automatically detects when a high number of devices are connected to a network and changes the dual radios in the access point from 2.4 GHz/5 GHz to 5 GHz/5 GHz to serve more clients. The access point performs this function while still monitoring the network for security threats and RF Interference that may affect performance. Flexible Radio Assignment improves mobile user experience for high-density networks.

FRA has the following different modes of operation:

•Default operating mode—Serving clients on both 2.4 GHz and 5 GHz radios.

•Dual 5 GHz Mode—Serving clients on both 5 GHz radios.

•Wireless Security Monitoring—Scanning both 2.4 GHz and 5 GHz radios for security threats while also serving 5 GHz clients.

What is a Smart Antenna connector?

The 2802E model has a Smart antenna connector (see Figure 8), which is connected directly to the flexible radio. Without a supported external antenna connected to the Smart Antenna connector, the flexible radio can stay only in 2.4 GHz mode. If an external antenna is connected, the flexible radio can be used in the full Flexible Radio Assignment mode, allowing dual 5 GHz and Wireless Security Monitoring modes.

To connect to any supported RP-TNC connector-type external antenna to the Smart antenna connector, use the DART cable connector AIR-CAB002-DART-R= (see Figure 9), which is to be procured separately from Cisco.

Figure 8 Smart Antenna Connector on 2802E Model

Figure 9 AIR-CAB002-DART-R= DART Connector

How Does Auto-Link Aggregation work with the 2800?

The 2800 AP supports automatic Link Aggregation (LAG) across its Ethernet and AUX ports. This provides up to 2 Gbps of uplink speed to the access point.

The following Cisco switching series support LAG with the 2800 AP:

• Catalyst 3850 / all models (non-CA mode)
• Catalyst 3650 / all models (non-CA mode)
• Catalyst 4500/Sup-8E
• Catalyst 6500/Sup 720 or newer

What is a ClientLink 4.0? How is it different from Tx-Beamforming?

Cisco ClientLink 4.0 is a beamforming capability built into Cisco Aironet wireless LAN access points. When the access point concentrates signals toward the receiving client, that client is better able to hear the AP’s transmission, and so throughput is greater. ClientLink also enhances performance in the uplink (client-to-AP) direction, so that the AP can also better hear the client communications. The result is improved performance in both directions, and doesn’t require any special capabilities in the client device to work.

ClientLink works with all client technologies. It makes sure each client type always operates at the best possible rate, as determined by the 802.11 access technology supported, network conditions, and the distance of the client from the Wi-Fi AP. ClientLink helps maintain maximum client rates.

Can the USB port be used?

The USB port does not have any software support at this time.

Manufacturers Federal Communication Commission Declaration of Conformity Statement

Manufacturer:

Cisco Systems, Inc.
170 West Tasman Drive
San Jose, CA 95134-1706
USA

This device complies with Part 15 rules. Operation is subject to the following two conditions:

1. This device may not cause harmful interference, and

2. This device must accept any interference received, including interference that may cause undesired operation.

This equipment has been tested and found to comply with the limits of a Class B digital device, pursuant to Part 15 of the FCC Rules. These limits are designed to provide reasonable protection against harmful interference when the equipment is operated in a residential environment. This equipment generates, uses, and radiates radio frequency energy, and if not installed and used in accordance with the instructions, may cause harmful interference. However, there is no guarantee that interference will not occur. If this equipment does cause interference to radio or television reception, which can be determined by turning the equipment off and on, the user is encouraged to correct the interference by one of the following measures:

• Reorient or relocate the receiving antenna.
• Increase separation between the equipment and receiver.
• Connect the equipment to an outlet on a circuit different from which the receiver is connected.
• Consult the dealer or an experienced radio/TV technician.

Caution The Part 15 radio device operates on a non-interference basis with other devices operating at this frequency when using the integrated antennas. Any changes or modification to the product not expressly approved by Cisco could void the user’s authority to operate this device.