Cisco LAP (Lightweight Access Point), Some Questions
A LAP is an AP that is designed to be connected to a wireless LAN (WLAN) controller (WLC). The LAP provides dual band support for IEEE 802.11a, 802.11b, and 802.11g and simultaneous air monitoring for dynamic, real-time radio frequency (RF) management. The Cisco LAP is part of the Cisco Unified Wireless Network architecture. In addition, Cisco LAPs handle time-sensitive functions, such as Layer 2 encryption, that enable Cisco WLANs to securely support voice, video, and data applications.
APs are “lightweight,” which means that they cannot act independently of a wireless LAN controller (WLC). The WLC manages the AP configurations and firmware. The APs are “zero touch” deployed, and individual configuration of APs is not necessary. The APs are also lightweight in the sense that they handle only real-time MAC functionality. The APs leave all the non-real-time MAC functionality to be processed by the WLC. This architecture is referred to as the “split MAC” architecture.
You cannot configure the LAP to operate independent of a wireless LAN controller (WLC). LAPs cannot function independent of WLCs. LAPs function in conjunction with a WLC only. The reason is that the WLC provides all the configuration parameters and firmware that the LAP needs in the registration process.
LWAPP (Lightweight AP Protocol) 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.
A LAP discovers a controller with the use of LWAPP discovery mechanisms. The LAP sends an LWAPP join request to the controller. The controller sends the LAP an LWAPP join response, which allows the AP to join the controller. When the LAP joins to the controller, the LAP downloads the controller software if the revisions on the LAP and controller do not match. Subsequently, the LAP is completely under the control of the controller. LWAPP secures the control communication between the LAP and the controller by means of a secure key distribution. The secure key distribution requires already provisioned X.509 digital certificates on both the LAP and the controller. Factory-installed certificates are referenced with the term "MIC", which is an acronym for Manufacturing Installed Certificate. Cisco Aironet APs that shipped before July 18, 2005, do not have a MIC. So these APs create a self-signed certificate (SSC) when they are upgraded in order to operate in lightweight mode. Controllers are programmed to accept SSCs for the authentication of specific APs.
And what is CAPWAP?
In controller software release 5.2 or later, Cisco lightweight access points use the IETF standard Control and Provisioning of Wireless Access Points protocol (CAPWAP) in order to communicate between the controller and other lightweight access points on the network. Controller software releases prior to 5.2 use the Lightweight Access Point Protocol (LWAPP) for these communications.
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 being implemented in controller software release 5.2 for these reasons:
- To provide an upgrade path from Cisco products that use LWAPP to next-generation Cisco products that use CAPWAP
- To manage RFID readers and similar devices
- 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 you use CAPWAP are the same as when you use 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 that runs CAPWAP or LWAPP. The only exception is the Cisco Aironet 1140 Series Access Point, which supports only CAPWAP and therefore joins only controllers that run CAPWAP. For example, an 1130 series access point can join a controller that runs either CAPWAP or LWAPP whereas an 1140 series access point can join only a controller that runs CAPWAP.
For more information, refer to the Access Point Communication Protocols section of the configuration guide.
Is it a regular AP or a LAP? The easiest way to distinguish between a regular AP and a LAP is to look at the part number of the AP.
- LAP (Lightweight AP Protocol [LWAPP])—Part numbers always begin with AIR-LAPXXXX.
- Autonomous AP (Cisco IOS Software)—Part numbers always begin with AIR-APXXXX.
The Cisco Aironet 1000 Series LAPs are an exception to this criteria. The part numbers of the 1000 series LAPs are:
- AIR-AP1010-A-K9 for a 1010 LAP
- AIR-AP1020-A-K9 for a 1020 LAP
- AIR-AP1030-A-K9 for a 1030 LAP
Note: The part numbers can vary, which depends on the country and regulatory domain. The part numbers that this list provides are just examples.
Make sure that you order the appropriate AP for your wireless LAN (WLAN).
These Cisco Aironet AP platforms are able to run LWAPP:
- Aironet 1500 Series
- Cisco Aironet 1250 Series
- Aironet 1240 AG Series
- Aironet 1230 AG Series
- Aironet 1200 Series
- Aironet 1130 AG Series
- Aironet 1000 Series
- Aironet 1140 Series AP
Note: The 1140 Series AP is supported only with WLC that runs 5.2 release or later.
Note: You can order these Aironet APs with Cisco IOS Software to operate as autonomous APs or to operate with LWAPP. The part number determines if an AP is a Cisco IOS Software-based AP or an LWAPP-based AP. Here are examples:
- AIR-AP1242AG-A-K9 is a Cisco IOS Software-based AP.
- AIR-LAP1242AG-P-K9 is an LWAPP-based AP.
Note: The 1000 Series APs and the 1500 Series APs are exceptions to this criterion. All the 1000 Series APs and the 1500 Series APs support only LWAPP.
How do I install and configure an LWAPP-enabled access point? LWAPP-enabled APs are part of the Cisco Integrated Wireless Network Solution and require no manual configuration before they are mounted. The AP is configured by an LWAPP-capable Cisco Wireless LAN Controller (WLC). Refer to the Quick Start Guide LWAPP-Enabled Cisco Aironet Access Points for information on how to install and initially configure an LWAPP-enabled access point.
If I want to configure my LAP and my wireless LAN controller (WLC) together, what shall I do? LAPs use Lightweight AP Protocol (LWAPP), and when they join a WLC, the WLC sends the LAPs all the configuration parameters and firmware. Refer to the Wireless LAN Controller and Lightweight Access Point Basic Configuration Example for a basic setup.
Also you cannot connect an autonomous AP to a wireless LAN controller (WLC) and expect the AP to work. Only LAPs work when they are connected to a WLC. Autonomous APs do not understand the Lightweight AP Protocol (LWAPP) or the CAPWAP protocol that the WLC uses. In order to connect an autonomous AP to a WLC, you must first convert the autonomous AP to lightweight mode.
The number of APs supported per WLC depends on the model number:
- 2106—A standalone WLC that supports up to 6 APs with 8 Fast Ethernet interfaces.
- 4402—A standalone WLC that supports either 12, 25, or 50 APs.
- 4404—A standalone WLC that supports 100 APs.
- 5500—A standalone WLC that supports 12, 25, 50,100, or 250 access points for business-critical wireless services at locations of all sizes.
- WLCM—A WLC module that is specifically designed for Cisco's Integrated Service Router (ISR) series. It's currently available in a 6, 8 or 12 AP version.
- WS-C3750G—A WLC that supports either 25 or 50 APs that comes integrated with the Catalyst 3750 switch. The WLC's backplane connections appear as 2-Gig Ethernet ports that can be configured separately as dot1q trunks to provide connection into the 3750. Or the Gig ports can be link aggregated to provide a single EtherChannel connection to the 3750. Because the WLC is integrated directly, it has access to all of the advanced routing and switching features available in the 3750 stackable switch. This WLC is ideal for medium-sized offices or buildings. The `50 AP' version can scale up to 200 APs when four 3750s are stacked together as a virtual switch.
- WiSM—A WLC module that is designed specifically for Cisco's Catalyst 6500 switch series. It supports up to 300 APs per module. Depending on the 6500 platform, multiple WISMs can be installed to offer significant scaling capabilities. The WiSM appears as a single aggregated link interface on the 6500 that can be configured as a dot1 trunk to provide connection into the 6500 backplane. This module is ideal for large buildings or campuses.
Reference from http: //www.cisco.com/c/en/us/support/docs/wireless/aironet-1200-series/70278-lap-faq.html
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