Table Of Contents

Overview

Product Terminology

Autonomous Access Points

Lightweight Access Points

Guidelines for Using Cisco Aironet Lightweight Access Points

Hardware Features

Radio Module Slots

Single or Dual-Radio Operation

Operating Modes

Spatial Multiplexing

Maximum Ratio Combining

Antennas Supported

LEDs

Ethernet Port

Console Port

Power Sources

UL 2043 Compliance

Anti-Theft Features

Network Examples with Autonomous Access Points

Root Unit on a Wired LAN

Repeater Unit that Extends Wireless Range

Central Unit in an All-Wireless Network

Workgroup Bridge Network

Network Example with Lightweight Access Points

Overview

---

The Cisco Aironet 1250 Series Access Point is available in autonomous and lightweight configurations. The autonomous access points can support standalone network configurations with all configuration settings maintained within the access points. The lightweight access points operate in conjunction with a Cisco wireless LAN controller with all configuration information maintained within the controller.

The 1250 series access point is a Wi-Fi certified, wireless LAN transceiver. The access point supports two (draft IEEE 802.11n version 2.0) radio modules: a 2.4-GHz radio and a 5-GHz radio.

You can configure the radios separately, using different settings on each. The access point connects wireless and wired networks or is the center point of a stand-alone wireless network. In large installations, wireless users within radio range of an access point can roam throughout a facility while maintaining seamless access to the network.

Product Terminology

The following terms refer to the autonomous and lightweight products:

•The term access point describes both autonomous and lightweight products.

•The term autonomous access point describes only the autonomous product.

•The term lightweight access point describes only the lightweight product.

•The term access point describes the product when configured to operate as an access point.

•The term bridge describes the product when configured to operate as a bridge.

Autonomous Access Points

---

Note Bridge mode is not supported for 802.11n or non-802.11n data rates. Also, Cisco does not recommend configuring bridge mode on the 1250 series access point even though the commands for it are available.

---

The autonomous access point (model: AIR-AP1252) supports a management system based on Cisco IOS software. The access point serves as the connection point between wireless and wired networks or as the center point of a stand-alone wireless network. In large installations, wireless users within radio range of an access point can roam throughout a facility while maintaining seamless access to the network.You can configure and monitor the access point using the command-line interface (CLI), the browser-based management system, or Simple Network Management Protocol (SNMP).

Lightweight Access Points

The lightweight access point (model: AIR-LAP1252) is part of the Cisco Integrated Wireless Network Solution and requires no manual configuration before being mounted. The lightweight access point is automatically configured by a Cisco wireless LAN controller (hereafter called a controller) using the Lightweight Access Point Protocol (LWAPP).

In the Cisco Centralized Wireless LAN architecture, access points operate in lightweight mode (as opposed to autonomous mode). The lightweight access points associate to a controller. The controller manages the configuration, firmware, and controls transactions such as 802.1x authentication. In addition, all wireless traffic is tunneled through the controller.

LWAPP is an Internet Engineering Task Force (IETF) draft protocol that defines the control messaging for setup and path authentication and run-time operations. LWAPP also defines the tunneling mechanism for data traffic.

In an LWAPP environment, a lightweight access point discovers a controller by using LWAPP discovery mechanisms and then sends it an LWAPP join request. The controller sends the lightweight access point an LWAPP join response allowing the access point to join the controller. When the access point is joined, the access point downloads its software if the versions on the access point and controller do not match. After an access point joins a controller, you can reassign it to any controller on your network.

LWAPP secures the control communication between the lightweight access point and controller by means of a secure key distribution, using X.509 certificates on both the access point and controller.

This chapter provides information on the following topics:

•Guidelines for Using Cisco Aironet Lightweight Access Points

•Hardware Features

•Network Examples with Autonomous Access Points

Guidelines for Using Cisco Aironet Lightweight Access Points

You should keep these guidelines in mind when you use a lightweight access point:

•Lightweight access points can communicate only with Cisco controllers, such as the Cisco 2106 or 4400 series controllers. For other controllers, check with your controller documentation to ensure your lightweight access points are supported.

•Lightweight access points do not support Wireless Domain Services (WDS) and cannot communicate with WDS devices. However, the controller provides functionality equivalent to WDS when the access point associates to it.

•Lightweight access points do not support Layer 2 LWAPP. They must get an IP address and discover the controller using DHCP, DNS, or IP subnet broadcast.

•The lightweight access point console port is enabled for monitoring and debugging purposes (all configuration commands are disabled when the access point is associated to a controller).

Hardware Features

Key hardware features of the access point include:

•Two radio module slots for single or dual-radio operation (see page 5)

•Ethernet port (see page 7) and console port (see page 8)

•LEDs, (see page 8)

•Multiple power sources (see page 8)

•UL 2043 compliance (see page 8)

•Anti-theft features (see page 9)

Figure 1-1 shows the access point with two radio modules installed.

Figure 1-1 Access Point with 2.4-GHz and 5-GHz Radio Modules

1	2.4-GHz radio antenna	4	5-GHz radio antenna
2	Module slot 0 (2.4-GHz radio module shown)	5	Module slot 1 (5-GHz radio module shown)
3	LEDs	6	PC cable security slot

Figure 1-2 illustrates a radio module. The access point supports three types of modules:

•2.4-GHz radio module—contains a 2.4-GHz (draft IEEE 802.11n version 2.0) radio and three antenna connectors.

•5-GHz radio module—contains a 5-GHz (draft IEEE 802.11n version 2.0) radio and three antenna connectors (identified with blue labels).

•Blank module—does not contain a radio or antenna connectors.

Figure 1-2 Radio Module - new pic

1	Radio antenna connector (A-Tx/Rx)	3	Radio antenna connector (B-Tx/Rx)
2	Radio antenna connector (C-Rx)

---

Note The 5-GHz antennas have a blue dot or blue label to correspond to the blue labels around the antenna connectors on the 5-GHz radio module.

---

Radio Module Slots

The access point has two radio module slots: Slot 0 and Slot 1 (see Figure 1-1). Slot 0 can only be used with the 2.4-GHz radio module and slot 1 can only be used with the 5-GHz radio module.

New radio configuration changes are associated with the specific module slot in which the radio module is located. When the default radio settings are changed, the radio modules should not be moved to a different slot. After configuration changes are made, moving the radio modules to a different modules slot requires that you re-configuring the radio settings for that slot.

Single or Dual-Radio Operation

The access point supports single or simultaneous dual radio (draft IEEE 802.11n version 2.0) operation using 2.4-GHz and 5-GHz radio modules. Each radio module contains an integrated radio with three antenna connectors. A blank module is supported for single radio access point configurations.

The 2.4-GHz radio supports 802.11b, 802.11g, and 802.11n modes of operation. The 2.4-GHz radio also supports 1 or 2 transmitting antennas and up to 3 receiving antennas.

The 5-GHz radio supports 802.11a and 802.11n modes of operation. The radio supports the Unlicensed National Information Infrastructure (UNII-1, UNII-2, and UNII-3), and the European Telecommunications Standards Institute / industrial, scientific and medical (ETSI/ISM) frequency bands. The 5-GHz radio also supports 1 or 2 transmitting antennas and up to 3 receiving antennas.

Operating Modes

The 2.4-GHz radio module supports four operating modes:

•802.11b single transmit antenna

•802.11g single transmit antenna

•802.11n HT-20 MHz with dual transmit antennas

•802.11n HT-40 MHz with dual transmit antennas

The 5-GHz radio module supports three operating modes:

•802.11a single transmit antenna

•802.11n HT-20 MHz with dual transmit antennas

•802.11n HT-40 MHz with dual transmit antennas

Spatial Multiplexing

The radio modules can support two transmitters to achieve faster data rates for a given bandwidth. This technique is called multiple input multiple output (MIMO) and relies on the premise that, via multi-path, two transmitted signals take different paths to the receivers. Using special data packet features allows the receivers to distinguish between the two transmitted signals and increases the access point data rate.

Maximum Ratio Combining

The radio modules use three receivers to support maximum ratio combining (MRC) to enhance receiver performance. MRC is a technique that combines the signals from multiple receivers in a manner to optimize the signals. MRC can provide up to 3 dB of increased receive signal strength in all modes of operation.

Antennas Supported

Table 1-1 lists the supported access point antennas.

Warning The access point, antennas, and all interconnected equipment including the associated LAN connections must be located indoors within the same building. Statement 375

---

Note The access point has been designed to operate with the antennas listed below and having a maximum gain of 10 dBi for 2.4 GHz and 6 dBi for 5 GHz. Antennas not included in this list or having a higher gain are strictly prohibited for use with the access point. The required antenna impedance is 50 ohms.

---

---

Note To reduce potential radio interference to other users, the antenna type and its gain should be chosen so that the equivalent isotropically radiated power (e.i.r.p.) is not more than required for successful communication.

---

Table 1-1 Supported Antennas 

2.4-GHz Antennas	Gain (dBi)	5-GHz Antennas	Gain (dBi)
AIR-ANT59591 diversity ceiling omnidirectional	2	AIR-ANT5135DG-R non-articulated omnidirectional	3.5
AIR-ANT2422DG-R non-articulated dipole	2.2	AIR-ANT5135D-R articulating dipole	3.5
AIR-ANT4941 articulating dipole	2.2	AIR-ANT5140V-R omnidirectional	4
AIR-ANT2430V-R omnidirectional	3	AIR-ANT5145V-R1 diversity ceiling omnidirectional	4.5
AIR-ANT1728 ceiling omnidirectional	5.2	AIR-ANT5160V-R1 omnidirectional	6
AIR-ANT2506 mast mount omnidirectional	5.2
AIR-ANT3213 diversity pillar omnidirectional	5.2
AIR-ANT2460P-R1 ceiling omnidirectional	6
AIR-ANT2465P-R1 diversity patch directional	6.5
AIR-ANT2485P-R1 patch directional	8.5
AIR-ANT2410Y-R yagi directional	10

1 The antenna has an attached UL2043 rated antenna cable.

LEDs

The access point has three LEDs (see Figure 1-1) to indicate Ethernet activity, radio activity, and status indications (refer to the "Checking the Autonomous Access Point LEDs" section or the "Checking the Lightweight Access Point LEDs" section for additional information).

•The Status LED provides general operating status and error indications.

•The Ethernet LED signals Ethernet traffic on the wired Ethernet LAN and provides Ethernet error indications.

•The Radio LED signals that wireless packets are being transmitted or received over the radio interface and provides error indications.

Ethernet Port

The Ethernet port is located on the bottom of the unit in the access point connector area (see Figure 1-3). The auto-sensing Ethernet port accepts an RJ-45 connector, linking the access point to your 10BASE-T, 100BASE-T, or 1000BASE-T Ethernet LAN. The Ethernet interface supports automatic media dependent interface crossover (MDIX) detection, which automatically senses cable type (straight-through or crossover) and adjusts the internal connections appropriately. Also the interface automatically senses the data rate being received over the connected cable.

The access point can receive power through the Ethernet cable from a 1250 series power injector. The Ethernet MAC address is printed on the label on the bottom of the access point.

Figure 1-3 Access Point Connector Area

1	DC power connector (+56 VDC)	3	Console port (RJ-45)
2	Ethernet port (RJ-45)	4	MODE button

Console Port

The console port is located on the bottom of the unit in the access point connector area (see Figure 1-3). The console port provides access to the access point's command-line interface (CLI) using a terminal emulator program. Use an RJ-45 to DB-9 serial cable to connect your computer's COM port to the access point's serial console port. Assign the following port settings to a terminal emulator to open the management system pages: 9600 baud, 8 data bits, no parity, 1 stop bit, and no flow control.

---

Note After completing your configuration changes, you must remove the serial cable from the access point.

---

The serial cable can be purchased from Cisco (part number AIR-CONCAB1200) or can be built using the pinouts in "Console Cable Pinouts."

Power Sources

The access point can receive power from a 1250 series DC power module or from inline power using the Ethernet cable. The access point supports the IEEE 802.3af inline power standard and Cisco CDP Power Negotiation. Using inline power, you do not need to run a power cord to the access point because power is supplied over the Ethernet cable.

The access point supports the following power sources:

•Cisco Aironet 1250 series DC power module (AIR-PWR-SPLY1)

•Inline power:

–Cisco Aironet 1250 series power injector (AIR-PWRINJ4)

–IEEE 802.3af power source (access point with only one radio module installed)

---

Note Current switches and patch panels do not provide enough power to operate the access point with both 2.4-GHz and 5-GHz radios. At power-up, if the access point is unable to determine that the power source can supply sufficient power, the access point automatically deactivates both radios to prevent an over-current condition. The access point also activates a Status LED low power error indication and creates an error log entry (refer to the "Checking the Autonomous Access Point LEDs" section or the "Checking the Lightweight Access Point LEDs" section).

---

UL 2043 Compliance

The access point has adequate fire resistance and low smoke-producing characteristics suitable for operation in a building's environmental air space, such as above suspended ceilings, in accordance with Section 300-22(c) of the NEC, and with Sections 2-128, 12-010(3) and 12-100 of the Canadian Electrical Code, Part 1, C22.1.

---

Caution The 1250 series power injector (AIR-PWRINJ4), the 1250 series DC power module (AIR-PWR-SPLY1), and the antennas are not tested to UL 2043 and should not be placed in a building's environmental air space, such as above suspended ceilings.

---

Anti-Theft Features

There are two methods of securing the access point:

•Padlock—You can lock the access point to the mounting plate with a padlock (see Figure 1-4). This prevents removing the radio modules and blocks access to the access point connector area. Compatible padlocks are Master Lock models 120T and 121T or equivalent. For additional information, refer to the "Securing the Access Point" section.

•Security cable keyhole—You can use the security cable slot (see Figure 1-1) to secure the access point using a standard security cable, like those used on laptop computers (refer to the "Securing the Access Point" section).

---

Note The mounting plate and padlock are required to prevent removal of the radio modules.

---

Figure 1-4 Access Point with Padlock-

Network Examples with Autonomous Access Points

This section describes the access point's role in three common wireless network configurations. The access point's default configuration is as a root unit connected to a wired LAN or as the central unit in an all-wireless network. The repeater role requires a specific configuration.

Root Unit on a Wired LAN

An access point connected directly to a wired LAN provides a connection point for wireless users. If more than one access point is connected to the LAN, users can roam from one area of a facility to another without losing their connection to the network. Figure 1-5 shows access points acting as root units on a wired LAN.

Figure 1-5 Access Points as Root Units on a Wired LAN

Repeater Unit that Extends Wireless Range

An access point can be configured as a stand-alone repeater to extend the range of your infrastructure or to overcome an obstacle that blocks radio communication. The repeater forwards traffic between wireless users and the wired LAN by sending packets to either another repeater or to an access point connected to the wired LAN. The data is sent through the route that provides the best performance for the client. Figure 1-6 shows an access point acting as a repeater. Consult the Cisco IOS Software Configuration Guide for Cisco Aironet Access Points for instructions on setting up the roles.

---

Note Non-Cisco client devices might have difficulty communicating with repeater access points.

---

Figure 1-6 Access Point as Repeater

Central Unit in an All-Wireless Network

In an all-wireless network, an access point acts as a stand-alone root unit. The access point is not attached to a wired LAN; it functions as a hub linking all stations together. The access point serves as the focal point for communications, increasing the communication range of wireless users. Figure 1-7 shows an access point in an all-wireless network.

Figure 1-7 Access Point as Central Unit in All-Wireless Network

Workgroup Bridge Network

The access point supports a workgroup bridge role to interconnect remote Ethernet workstations to the main LAN. The workgroup bridge can communicate with an access point (see Figure 1-8) or with a bridge (see Figure 1-9).

Figure 1-8 Workgroup Bridge Communicating with an Access Point

Figure 1-9 Workgroup Bridge Communicating with a Bridge

Network Example with Lightweight Access Points

The lightweight access points support Layer 3 network operation. Lightweight access points and controllers in Layer 3 configurations use IP addresses and UDP packets, which can be routed through large networks. Layer 3 operation is scalable and recommended by Cisco.

This section illustrates a typical wireless network configuration containing lightweight access points and a Cisco Wireless LAN Controller (see Figure 1-5). Consult the Cisco Wireless LAN Controller Configuration Guide for instructions on setting up the lightweight access points.

Figure 1-10 Typical Lightweight Access Point Network Configuration Example