Cisco Client Adapters

As we move down the wireless food chain, we come to the devices connecting users with the wireless network. Wireless adapters can be fitted to a multitude of devices client PCs, personal digital assistants, network printers, and so forth. Cisco offers four client adapters for its Aironet line:

• Cisco Aironet 350
• Cisco Aironet 802.11a, 802.11b, and 802.11g CardBus Wireless Client LAN Adapter
• Cisco Aironet 802.11a, 802.11b, and 802.11g Peripheral Component Interconnect (PCI) Wireless Client LAN Adapter
• Cisco Aironet 5 GHz 802.11a Adapter

The type of client adapter you use depends on what type of computer you need to connect. Laptops and other devices with Personal Computer Memory Card International Association (PCMCIA) and CardBus combination slots use a CardBus device. Desktop and tower-style PCs use PCI adapters.


Cisco Aironet 350


The entry-level model of Cisco client adapters is its venerable Aironet 350 adapter, shown in Figure 1-15. These adapters are designed as PCMCIA or PCI devices, which allow them to work with both desktop and laptop PCs.

These adapters can be used in either ad hoc (meaning two or more computers connect among themselves) or infrastructure environments (meaning the clients connect to a WLAN) and use the 802.11b protocol, which allows them to work in the 2.4-GHz band with a range up to 800 feet at 11 Mbps. Although this product operates at just 11 Mbps, it is compatible with 802.11g APs (although speed is limited to the adapter's top speed of 11 Mbps).


Cisco Aironet 802.11a, 802.11b, and 802.11g CardBus and PCI Wireless Client LAN Adapters

The Aironet 802.11 a/b/g CardBus and PCI Wireless Client LAN Adapters allow for a variety of uses and applications. Although they provide the same functionality, the difference between the CardBus and PCI devices is their physical design and construction. The CardBus devices are suited for laptops and tablet PCs, but the PCI device is meant for desktop PCs.

The CardBus device (shown in Figure 1-16) plugs into an open CardBus or combo CardBus/PCMCIA slot and the end sticks out an inch or so, allowing its internal antenna to communicate with the WLAN. The PCI device (shown in Figure 1-17) is a card that plugs into an open PCI slot on the PC. The card is connected to a small antenna that can be adjusted for best connectivity to the WLAN.


In spite of their physical differences, the devices offer the same functionality and are the most feature-rich and functional. They both offer:

• 802.11a coverage
• 802.11b coverage
• 802.11g coverage
• Dual mode 802.11a and 802.11g coverage
• Trimode 802.11a, 802.11b, and 802.11g coverage

These devices support Wi-Fi Protected Access (WPA) and WPA2. They also support 802.1X authentication, which includes LEAP, EAP-TLS, PEAP-GTC, EAP-FAST, and PEAP-MSCHAP V2.


Cisco Aironet 5 GHz 802.11a Adapter

The Cisco Aironet 5 GHz 802.11a Adapter serves clients that need access to a WLAN using 802.11a technology, shown in Figure 1-18. This device uses a CardBus form and is designed for use with APs, such as the Cisco Aironet 1200 Series 802.11a AP or the Aironet 1130AG AP.

Because the device offers 802.11a functionality, it operates at speeds of up to 54 Mbps in the 5-GHz band. Data rates can be reduced to extend the device's range.

The adapter uses the Cisco Wireless Security Suite, which offers the EAP framework for user-based authentication. It also supports a number of 802.1X authentication modes that include Cisco LEAP, EAP-TLS, PEAP, and EAP-SIM.

Cisco Wireless Bridges

In the past, connecting buildings on a campus or constructing a metropolitan-area network (MAN) required copper, fiber optic cabling, or expensive microwave equipment. Thanks to Wi-Fi technology, it is possible to unite geographically dispersed networks wirelessly. Cisco provides several options for wireless network connectivity.

The ranges for these devices depend on a number of factors, especially the antenna. Antennas are explained in greater detail in Chapter 2.

As you read through the product descriptions for APs and bridges (and later when client adapters are introduced), you might wonder why it is important to have an AP or bridge with a range of several thousand feet, or even a few miles, especially when client adapters can reach only a few hundred feet. It is important to understand that bridges and APs serve different functions. Although the job of an AP is to provide a point of connection to wireless clients, a bridge's main function is to connect with other bridges, and it serves as a link between two or more networks. APs, on the other hand, can also be added to enhance the range of a WLAN. Extending the network by adding APs can provide access to clients that are too far away from the WLAN to connect. As such, the greater ranges that APs and bridges afford are useful when bridges have to communicate with each other and when APs are placed to increase overall range.


Cisco Aironet 1300 Series as a Bridge

As noted in the previous section, the Cisco Aironet 1300 can be used as an outdoor AP or it can be used to connect several LANs in a MAN or campus environmentor even mobile networks. For optimal results in this capacity, the AP must be configured with the proper antenna.

The Aironet 1300 can serve as either a point-to-point or point-to-multipoint bridge. This is illustrated in Figure 1-12.


The Aironet 1300 bridge can also perform double duty. While connecting with bridges at other sites, the Aironet 1300 can simultaneously perform the functions of a wireless AP, accepting wireless clients.

If operating as a workgroup bridge, the Aironet 1300 connects wired Ethernet-enabled devices (laptops, network printers, and so on) to your WLAN. When the bridge is connected to an Ethernet switch, up to 255 devices can be added. Figure 1-13 illustrates this.

The Aironet 1300 comes with either integrated antennas or it can be purchased with connectors for external antennas.

As noted in the AP section, the Aironet 1300 bridge is capable of 802.11g. It offers a range up to 9 miles (in the United States) at 11 Mbps. For vehicle deployments, vehicles traveling over 60 mph (100 kph) with data rates at 12 Mbps and 24 Mbps and 128-byte packets experience a 1 percent packet error rate.


Cisco Aironet 1400 Series

Like the Aironet 1300, the 1400 seriesshown in Figure 1-14comes with either an integrated antenna or connectors for optional external antennas.

Using the 802.11a protocol, the Aironet 1400 with a built-in antenna allows 54-Mbps data rates up to 8.5 miles for point-to-point links and up to 2.75 miles for point-to-multipoint links. Adding an upgradeable antenna, speeds of 9 Mbps can be achieved at a distance of 23 miles.

The Aironet 1400 can be deployed in several ways, depending on your network's need. For example, it can be configured to be the singular connection between two geographically disparate networks. Alternately, it can be used as either the primary or the backup connection, in tandem with a second type of connection, such as a T1 line.

The Cisco Wireless Security Suite manages security on both the Aironet 1300 and 1400 series. Centralized management is employed through a Remote Authentication Dial-In User Service (RADIUS) server.

Cisco Aironet APs

APs are the devices that connect to the LAN, providing wireless access to the network. Wireless clients communicate with APs to access LANs or WLANs, as shown in Figure 1-1.


APs serve either as the core of an all-wireless network or as a point of connection between the wired and wireless networks. In addition, APs can be located throughout an organization to ensure access at remote locations in a facility.

Cisco features several models of APs. The model that fits best for your organization depends on a number of factors, which include:

• The number of wireless devices accessing the WLAN.
• The desired range.
• The desired speed.
• Your budget.

The following sections examine the Cisco Aironet APs, with specific details of each model.


Cisco Aironet 1100 Series
The Aironet 1100 AP (shown in Figure 1-2) includes a single radio and supports the 802.11g protocol. 802.11g is backward compatible to support the earlier 802.11b protocol. The most important distinction between 802.11b and 802.11g is the data rate802.11b provides 11 Mbps, whereas 802.11g allows up to 54 Mbps.


The 802.11b device can be upgraded to 802.11g capability. The 802.11g version allows wireless networks to leverage their investment on existing 802.11b equipment. It is also capable of 54-Mbps speeds with any new equipment. The Aironet 1100 AP allows the use of up to 16 virtual LANs (VLANs) and quality of service (QoS) functions. The AP also features hot standby and load balancing, which allow an organization to deploy intelligent network services and ensure network reliability and availability.

VLANs allow an organization to segment its users into their own discrete LANs. Thus, individual LAN policies, services, security levels, and QoS levels can be established for different groups of users.


Aironet 1130AG Series AP
The 1130AG AP builds on the functionality and utility of the Aironet 1100 Series AP. This AP uses two built-in radios (802.11a and 802.11g) for optimal coverage and usability.

Shown in Figure 1-4, the 1130AG AP employs two internal antennas for omnidirectional coverage. The ring on the front of the device changes color, depending on its current state. For example, when nothing is associated, the ring glows a pale green. When one or more devices have associated, it glows blue. If an error occurs, it glows red.


Because the AP employs both 802.11a and 802.11g radios, it affords a capacity of up to 108 Mbps. In addition, because both radios are used, it can handle 15, nonoverlapping channels (12 from the 802.11a radio and 3 from the 802.11g radio). In a future firmware upgrade, this capacity will increase to 22 channels. This will ensure less interference with neighboring WLANs and fewer transmission errors.


Cisco Aironet 1200 Series
The big brother to the Aironet 1100 is the Cisco Aironet 1200. The 1200 series (shown in Figure 1-5) incorporates single or dual radios, and it allows connectivity in both the 2.4-GHz (802.11g) or 5-GHz (802.11a) bands. The device can be configured for optimal flexibility (as shown in Figure 1-6), and it can be set up to operate solely in the 802.11a, 802.11b, or 802.11g mode. Alternately, it can be set in dual mode, which allows connectivity for clients operating in two different protocols. Ultimately, it can be set in trimode, to offer simultaneous service for all three protocols. This functionality provides great flexibility and return on investment because devices using any of the popular protocols can be used.


Like the Aironet 1100 series, the Aironet 1200 offers up to 16 VLANs, QoS capabilities, and Cisco Wireless Security Suite manages its security set.

The Aironet 1200 series is an important component in the Cisco Structured Wireless-Aware Network (SWAN). SWAN is a framework for deploying, operating, and managing thousands of Aironet APs when using a Cisco infrastructure.

For 802.11a networks, the Aironet 1200 series offers a variety of antennas including one that can be configured omnidirectionally (in a circle surrounding the AP) or as a patch antenna that directs a hemispherical signal from the wall and across the room.


Aironet 1230AG Series AP
The Aironet 1230AG Series AP provides many of the same features as its younger brother, the 1130AGchiefly dual 802.11a and 802.11g radios. However, the Aironet 1230AG is designed for environments in which omnidirectional antennas would be lacking. The 1130AG AP employs only internal antennas, but the 1230AG AP features connectors for external antennas.

This is ideal in environments such as factories, warehouses, or large retail facilities that require specialized antennas for proper functionality. Figure 1-7 shows this device.


Like other AP offerings from Cisco, the Aironet 1230AG AP is a component of the Cisco SWAN framework that delivers an integrated wired and wireless network.

Because the device uses both 802.11a and 802.11g radios, up to 15 nonoverlapping channels are available. This number will increase to 22 channels in a future firmware release.

The Aironet 1230AG AP is rugged enough to withstand high levels of heat.


Cisco Aironet 1300 Series
For outdoor wireless applications, Cisco offers its Aironet 1300 Series of APs, shown in Figure 1-8. These APs are encased in a tough, durable exterior, which makes them well suited for operation in the elements. In addition to its work as an AP, this device is also used as a network bridge.

The Aironet 1300 supports the 802.11g standards, providing data transfer rates of up to 54 Mbps.

These APs are not just for employees to take their laptops outside during lunch breaks. A number of organizations that benefit from an outdoor AP include the following:

• Campus networks For multibuilding organizations (schools, apartment buildings, hospitals, and so on), Wi-Fi makes interbuilding networks easy and inexpensive.
  

• Nomadic users Networks and users are not just tethered to their desks, offices, or even buildings. Many users work in trucks, vans, cars, or ambulances and require connectivity to the network. To resolve this problem, outdoor, Wi-Fi networks come in handy.
  

• Outdoor public access Wi-Fi hotspots pop up at many places, such as coffee shops, libraries, hotels, and now truck stops. As hotspots grow, devices such as the Cisco Aironet 1300 can be employed to provide Wi-Fi access to large outdoor areas.
  

• Temporary access The Aironet 1300 is a good solution when a temporary wireless network is needed. For example, aid workers caring for victims of a natural disaster can employ this sort of device to provide easy, reliable connectivity among its users and devices.

Airespace

Cisco completed its acquisition of a company called Airespace in early 2005. Now, the new Cisco 1000 Series Lightweight AP and WLAN controllers are included in its Wi-Fi catalog. These components work in tandem to deliver easy setup and configuration and a robust radio frequency (RF) environment.

Cisco 1000 Series Lightweight AP
This device has its benefits. It can be installed and connected to the network, with no configuration or setup needed on the AP, because configuration data is downloaded to the thin AP from a WLAN controller. This device is shown in Figure 1-9.

Although its easy installation and setup are big selling points for this device, it does much more. Because the AP's functioning is somewhat centralized to the WLAN controller, the AP can feed information about the RF environment back to the WLAN controller and the Cisco Wireless Control System. This allows these applications to make real-time decisions.

The data is forwarded and the RF environment monitored, which eliminates the need for additional nodes dedicated to those management functions. In turn, the overall network design is much simpler and more cost efficient. Within the 1000 series are three models:

• 1010 Offers two internal, sectorized antennas, used in places such as classrooms or office spaces.
  

• 1020 Offers two internal, sectorized antennas and connectors for external antennas, used in places such as factories or for outdoor applications.
  

• 1030 Offers two internal, sectorized antennas and connectors for external antennas. Also known as a Remote-Edge AP, this device is designed for use at branch offices to communicate with centrally located WLAN controllers using WAN technologies. This allows IT staff to centrally control service set identifiers (SSID), security settings, and configuration for a cohesive wireless environment.

The 1000 series allows power over Ethernet connections and over the air QoS.

The 1000 series also operates using 802.11a and 802.11g radios, affording compatibility with both standards and operation on up to 15 nonoverlapping channels.

Cisco WLAN Controllers

Earlier, we discussed the lines of the Cisco Lightweight APs. The APs and wireless control system are two legs of a three-legged stool; WLAN controllers comprise the other.

WLAN controllers are the hub of systemwide WLAN operation. They are the devices on which information is stored and disseminated to thin APs. In return, environmental data is sent back to the WLAN controller for analysis and action. The information stored on the WLAN controllers includes:

• Voice and data service
• Security policies
• Intrusion prevention
• RF management
• QoS
• Mobility
• Thin AP configuration

WLAN controllers communicate with the thin APs over Layer 2 or Layer 3 infrastructure using the Lightweight Access Point Protocol (LWAPP). This protocol ensures that communication between WLAN controllers and thin APs is secure.

Cisco offers three series of WLAN controllers: the 2000 Series, the 4100 Series, and the 4400 Series.

The Cisco 2000 Series WLAN controller is targeted at small- to medium-sized enterprise applications. Its 2006 model is capable of controlling up to 6 thin APs. The 2000 is shown in Figure 1-10.


The Cisco 4100 Series WLAN controller is targeted at medium- to large-sized enterprise applications. Its three modelsthe 4112, 4124, and 4136offer support to 12, 24, or 26 thin APs, respectively. This series features dual Gigabit Ethernet uplinks for LAN connectivity. The 4100 Series is shown in Figure 1-11.


These WLAN controllers can detect and adapt to changes in the RF environment. This level of management affords the following functionality:

• Channels are dynamically assigned to optimize network coverage and lessen interference.
• The system detects interference and makes changes to the network to remedy the interference.
• Load balancing prevents a large number of users from overburdening a specific thin AP.
• The power outpoint of the thin APs is adjusted to detect and correct coverage holes.
• Power is automatically adjusted across the network to specific APs, based on changing network conditions.

WLAN controllers use up-to-date security features that include WPA2, WPA, WEP, multiple EAP types, and a VPN termination module for IPSec and Layer 2 Tunneling Protocol.

Other security features include:

• The capability to detect and avoid unwanted RF propagation.
• Intrusion prevention and location to ensure that rogue APs are not only found, but located.
• Network admission control that manages client access based on policies.

Because the WLAN controller operates at both Layer 2 and 3 levels, users can roam among APs, switches, and routed subnets without interruption in service. In addition, security and QoS information follows them, so the operation environment is consistent.