WLAN Components

Client devices use wireless NICs or adapters to connect to a wireless network in either ad hoc (peer-to-peer) mode or infrastructure mode using APs. Cisco APs can be either autonomous or lightweight.

NOTE Autonomous APs used to be called thick, fat, or decentralized APs, whereas lightweight APs were called thin or centralized APs.

These components are described in the following sections.

Cisco-Compatible WLAN Clients

The Cisco Compatible Extensions (CCX) program for WLAN client devices allows vendors of WLAN client devices or adapters to ensure interoperability with the Cisco WLAN infrastructure and take advantage of Cisco innovations. Wireless client products are submitted to an independent lab for rigorous testing; passing this testing process allows the devices to be marketed as Cisco Compatible client devices. There are four versions of the Cisco Compatible specification, versions 1 through 4. Each version builds on its predecessors; with a few exceptions, every feature that must be supported in one version must also be supported in each subsequent version.

Autonomous APs

An autonomous AP has a local configuration and requires local management, which might make consistent configurations difficult and add to the cost of network management.

Cisco's core WLAN feature set includes autonomous APs and the CiscoWorks Wireless LAN Solutions Engine (WLSE) management appliance.

KEY POINT

CiscoWorks WLSE is a turnkey and scalable management platform for managing hundreds to thousands of Cisco Aironet autonomous APs and wireless bridges. Autonomous APs may also be configured with CiscoWorks WLSE Express, a complete WLAN management solution with an integrated authentication, authorization, and accounting (AAA) server for small to medium-sized enterprise facilities or branch offices using Cisco Aironet autonomous APs and wireless bridges.

Lightweight APs

KEY POINT

A lightweight AP receives control and configuration from a WLAN controller (WLC) to which it is associated. This provides a single point of management and reduces the security concern of a stolen AP.

The WLCs and lightweight APs communicate over any Layer 2 (Ethernet) or Layer 3 (IP) infrastructure using the Lightweight AP Protocol (LWAPP) to support automation of numerous WLAN configuration and management functions. WLCs are responsible for centralized systemwide WLAN management functions, such as security policies, intrusion prevention, RF management, quality of service (QoS), and mobility.

KEY POINT

The Cisco advanced WLAN feature set includes lightweight APs, WLCs, and the Wireless Control System (WCS) management application. These components are the basis for the Cisco UWN.

A Cisco wireless location appliance may be added to track the location of wireless devices. AP Power

One issue for WLANs is that power might not be available where APs need to be located. Two solutions to this issue are Power over Ethernet (PoE) and power injectors. PoE, or inline power, provides operating current to a device, such as an AP, from an Ethernet port, over the Category 5 cable.

NOTE The IEEE 802.3af standard defines PoE. In addition, some Cisco devices support a prestandard proprietary method of powering devices over Ethernet. An optional power classification feature allows switches to recognize powered devices and identify their power requirements.

A midspan power injector is a standalone unit that adds PoE capability to existing networking equipment. The power injector is inserted into the LAN between the Ethernet switch and the device requiring power, such as an AP.

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