Wireless LAN Controllers

The entire design of the Wireless LAN Controllers is for scalability. The communication between a lightweight AP can happen over any type of Layer 2 or Layer 3 infrastructure using LWAPP. There are integrated controller platforms designed for installation in switches. The 3750-G actually comes as an integrated 2RU switch with either a 25 or 50 AP controller, as well as the WiSM and the WLCM. These are both modular controllers that can be installed in 6500 series switches or in Integrated Services Routers (ISR). There are also appliance-based controllers, which include the 44xx series WLC as well as the 2100 series WLC. Which controller you require depends on how many APs you need de- ployed. This can be anywhere from six to 300 access points per controller. This is a fixed value and can’t be upgraded via licensing. If you need to support more APs, you need an- other controller or a controller that supports more APs.


The Cisco 44xx Series WLC

The Cisco 44xx series Wireless LAN Controller, shown in Figure 10-8, is a standalone appliance.


It is designed to take up one rack unit. It has either two or four Gigabit Ethernet uplinks, and they use mini-GBIC FSG slots. It can support 12, 25, 50, or 100 APs, depending on the model. And it can support up to 5000 MAC addresses in its database.

The 4400 series has a 10/100 interface called a service port; it is used for SSH and SSL connections for management purposes. The service port can be used for out-of-band management, but it is not required to manage the device. You can manage the device via the controller’s logical management interface. There is also a console port that you can use to connect via HyperTerminal or Teraterm Pro.

Depending on the country you are in, power requirements vary, but the chassis has two power supply slots.

The controller code version used for the CCNA Wireless exam is version 5.x, and the AP runs the same version. It’s actually a requirement that they run the same version, so when an AP joins with a controller, the controller upgrades or downgrades the AP. The con- troller upgrades four APs at a time. The 4400 series can support up to 100 access points. So, a 4400 would upgrade ten APs at a time until they are all upgraded.


The Cisco WiSM

The Cisco WiSM, shown in Figure 10-10, is a services module that installs in the 6500 se- ries switch or 7600 series router with the Cisco Supervisor Engine 720.


It has the same functionality as the 4400 series standalone controllers; the difference is that it supports up to 300 APs. The WiSM supports 150 access points per controller, with each blade having two controllers. Thus, you can have a total of 300 access points. You can also cluster 12 of them into a mobility domain. This allows up to 7200 lightweight APs in a mobility domain.


The Cisco 2106 WLC

The Cisco 2106 Wireless LAN Controller, shown in Figure 10-11, is also a single-rack unit design with eight 10/100 Ethernet ports.


It can support up to six primary access points. It has an RJ-45 console port and two RJ-45 ports that support PoE. It has nearly all the same features as the 4400 series controllers but has eight built-in switch ports. You can expect to see this controller in a small branch environment.


The Cisco WLCM

The Wireless LAN Controller Module (WLCM), shown in Figure 10-12, is designed for the ISR routers. You would see this controller in a small office.


It has the same functionality as the 2106, but it does not have the directly connected AP and console port. It supports six APs. The WLCM-Enhanced (WLCM-E) supports eight or 12 APs, depending on which module you get.

Of course, some limitations apply. Most of the features are similar to the 4000 series:

• LWAPP

• RF control

• The ability to be a DHCP server

• Layer 2 security

The differences are things such as the following:

• Lack of PoE ports

• The number of APs supported

• The LWAPP modes supported

Wireless LAN Controller Summary

Table 10-3 summarizes the Cisco Wireless LAN Controller models.