Access Points

As previously mentioned, there are two types of access points:

• Autonomous APs

• Lightweight APs

Some APs are built into modules and deployed in ISR routers at branch sites; other APs are deployed as just standalone devices. Cisco APs are known to offer the best range and throughput in the industry, as well as a number of security features that you do not find with other vendors.

Cisco APs offer multiple configuration options. Some of them support external antennas, some support internal antennas, and some are to be deployed outdoors. Still others are de- signed to be deployed indoors. Some APs are designed to be implemented for wide-area networking and bridging purposes and, while operating as a bridge, may also allow client connections. The point is that Cisco APs can serve a number of purposes.

The benefit of the CUWN APs is that they are zero-touch management, assuming that Layer 2 connectivity is already in place. As soon as they are plugged in and powered on, you don’t have to do anything else at the AP level. The models that you need to be familiar with for the CCNA Wireless exam include the 1130AG, 1240AG, 1250AG, 1300, and 1400 series wireless bridges.

The 1130, 1240, and 1250 can be both autonomous and lightweight APs. Whereas the 1300 and 1400 series are designed to operate as bridges, the 1300 series can also sup- port wireless clients. In turn, the 1400 series supports bridging only. Another model is the outdoor mesh 1500 series, which supports only LWAPP, so that would be designed for a lightweight scenario only.

Cisco is known for being ahead of the curve. That’s where the special functionality of the 1250AG comes in. The 1250AG is one of the first access points to support the 802.11n draft version 2.0 standard and is the basis for all 802.11 Wi-Fi interoperability testing. For a client vendor to get the v2.0 stamp of approval, it must be validated against the 1250, and the 1250 is the only AP used during this validation.

The 1130AG

The 1130AG, shown in Figure 10-3, is a dual-band 802.11 a/b or g AP that has integrated antennas.

The 1130AG can operate as a standalone device or in lightweight AP mode. It also can op- erate as a Hybrid Remote Edge AP (H-REAP) device. An H-REAP device operates on the far side of a WAN, and its controller is back at the core site.

The 1130AG is 802.11i/WPA2-compliant, and it has 32 MB of RAM and 16 MB of flash memory. The 1130 AP typically is deployed in office or hospital environments. Naturally, the internal antennas do not offer the same coverage and distance as APs that are designed for external antennas. Consider the 1130s. They have 3 dB gain and 4.5 dB gain for the 2.4- and 5-GHz frequencies, respectively. If you were to compare the 1131 to the 1242 with the 2.2 dipole antennas, you would see a larger coverage area than with the 1242.


The 1240AG


The 1240AG series AP, shown in Figure 10-4, is also a dual-band 802.11 a/b or g device, similar to the 1130AG; however, it supports only external antennas.

Those external antennas would connect using the RP-TNC connectors. The 1240AG can operate as an autonomous AP and in lightweight AP mode. Like the 1130AG, it also can operate in H-REAP mode. It too is 802.11i/WPA2-compliant.


The 1250 Series AP

Shown in Figure 10-5, the 1250 series AP is one of the first enterprise APs to support the 802.11n draft version 2.0.

Because it supports the 802.11n draft standard, you can get data rates of about 300 Mbps on each radio and the 2-by-3 multiple input and multiple output technology. The 2-by-3 is discussed in Chapter 6, “Overview of the 802.11 WLAN Protocols.” Also, because the 1250 is modular, it can easily be upgraded in the field. It operates in controller-based and standalone mode and is also 802.11i/WPA2-compliant.

The 1250 is designed for a more rugged type of indoor environment. You might see this at more hazardous locations such as packaging plants, or in situations where you might need


to place an antenna in a hazardous location and the AP elsewhere. You might see this type of AP in factories and hospitals. It has 64 MB of DRAM and 32 MB of flash memory. It has 2.4-GHz and 5-GHz radios.

Cisco Wireless Networks Architecture

The Need for Centralized Control

There is certainly a need for centralized control in wireless deployments today. Initial wireless deployments were based on standalone access points called autonomous access or fat APs. An autonomous AP is one that does not rely on a central control device. Al- though this is a great start, the problem lies in scalability. Eventually, you will have prob- lems keeping your configurations consistent, monitoring the state of each AP, and actually taking action when a change occurs. You end up with holes in your coverage area, and there is no real dynamic method to recover from that. There is certainly a need for central- ized control, and the Cisco Unified Wireless Network (CUWN) is based on centralized control.

Eventually you will want or need to convert those standalone APs, if possible, to light- weight APs. A lightweight AP is managed with a controller.

Traditionally after a site survey, you would deploy your wireless network based on the in- formation you gathered. As time passes, the environment you did the original site survey in will change. These changes, although sometimes subtle, will affect the wireless cover- age. The CUWN addresses these issues.


The Cisco Solution

The CUWN solution is based on a centralized control model. Figure 10-1 illustrates the numerous components of the CUWN.


An AP operating in lightweight mode gets its configuration from the controller. This means that you will perform most of your configuration directly on the controller. It dy- namically updates the AP as the environment changes. This also allows all the APs to share a common configuration, increasing the uniformity of your wireless network and eliminat- ing inconsistencies in your AP configurations.


As you can see, five functional areas exist:

• Wireless clients

• Access points

• Network unification

• Network management

• Network services

Supporting Multiple Networks

Previous chapters discussed that an AP can actually advertise multiple SSIDs, which lets the AP offer guest access as well as corporate user access and maybe even access for wire- less IP phones. Each Wireless LAN Controller actually can support 512 different VLAN instances. Remember that on the connection between the AP and the Wireless LAN Con- troller, all your wireless client data is passed via the LWAPP tunnel as it travels toward the wired domain.

To review, recall that an SSID exists only in the wireless space. An SSID is then tied to a VLAN within the controller. Each lightweight AP can support 512 different VLANs, but you don’t very often see that many on one AP.

On the other hand, your Wireless LAN Controller can have up to 16 wireless LANs (WLAN) tied to each AP. Each WLAN is assigned a wireless LAN identification (WLANID) by the controller. This is a number between 1 and 16, and you don’t get to choose which one to use.

So, now you have a WLAN that brings together the concept of an SSID on the wireless space and a VLAN on the wired space. By having separate WLANs, you can assign differ- ent quality-of-service (QoS) policies to the type of traffic encountered on each of them. An example of this would be to have a WLAN for IP Phones and a different WLAN for regular network users.

Each AP supports up to 16 SSIDs; generally, one SSID is mapped to one VLAN. With that said, even though a Wireless LAN Controller can support up to 512 VLANs per AP, you see a maximum of only 16 VLANs in most situations.


The CUWN Architecture

The Cisco Unified Wireless Network defines a total of five functional areas or intercon- nected elements, as shown in Figure 10-2.

The five elements or components all work together. It’s no longer about point products, where you can buy a standalone AP and deploy it and then later get management software to handle it. Today it is all about everything working together to create a smarter, more functional net- work. To illustrate how it all comes together, consider a Cisco wireless network. This type of network includes the following wireless clients (the first component of the CUWN):

• Cisco Aironet client devices

• Cisco-compatible client devices (not necessarily Cisco products, but still compatible)

• Cisco Secure Services Client (SSC)

The client devices get a user connected.

The second component, the access point, is dynamically managed by your controllers, and they use LWAPP to communicate. The AP bridges the client device to the wired net- work. A number of APs that could be discussed here are as follows:

• The 1130AG

• The 1240AG

• The 1250AG

• The 1300 series bridge

• The 1400 series bridge

• The 1500 series outdoor mesh