The Cisco WLAN (Aironet) Products Family
The wireless product line that Cisco offers provides considerable flexibility in designing a wireless solution for a wide range of SMB requirements. The 1400 series bridges extend the reach of wire-based LANs or WLANs for distances in excess of 20 miles (32 kilometers) and throughput rates of multiple T1/E1s.
Dual-mode APs from the 1200 series support both 802.11a and 802.11b standards, which makes them an effective integration tool in wireless scenarios that already deploy or desire to deploy clients that comply with either standard. The 1200 series APs are also available in the 802.11g standard, and the 802.11a/b units are field upgradeable to 802.11g. Client NICs are available in all three standards: 802.11a, 802.11b, and 802.11g. A wide range of antennae allow for the fine-tuning of transmission power and distance requirements.
All products incorporate extensive security support. Consider these wireless products and their characteristics in more detail in the context of creating an effective wireless infrastructure and client environment.
The 1400 Series Bridges
The 1400 series bridges are an element of the network infrastructure whose purpose is to create wireless high-capacity point-to-point or point-to-multipoint links that extend the boundaries of a LAN in areas where wired infrastructure is not feasible. The 1400 bridge complies with the 802.11a standard, which means that data rates up to 54 Mbps are possible.
Configuration of the bridge radio settings allows for the selection of data rates ranging from 6 Mbps through 54 Mbps, with the intervening options being 9, 12, 18, 24, 36, and 48 Mbps. Bridge configuration also allows for the optimization of throughput so that the bridge transmits at the highest rate possible as a function of changes in the transmission path environment.
In practice, lower data rates are selected for longer distances between the bridges, and data rates are likely to vary from the product specification as a function of obstacles in the transmission path. The 1400 series bridges operate in pairs for point-to-point configurations and in larger groups for point-to-multipoint scenarios. For point-to-point transmissions, the 1400 is specified for 12 miles (approximately 19.2 kilometers) at 54 Mbps and for 23 miles (approximately 36.8 kilometers) at 9 Mbps using the 28-dBi dish antennae. Other antenna options for the 1400 include the 9.0-dBi vertically polarized omni antenna and the 9.5-dBi sector antenna, which supports vertical or horizontal linear polarization.
The 1400 series bridges are well suited as an alternative to outdoor leased lines, but nothing prevents them from being deployed indoors as well. A data rate of 54 Mbps is roughly equivalent to the capacity of 35 T1s, or 1 T3 + 7 T1s.
TIP
Given that the 1400 series bridges are LOS devices with a maximum transmission distance of about 23 miles, they qualify for extending a LAN or creating a MAN rather than being a key building component in a long-haul WAN. Ultimately, however, how the 1400 bridges will be deployed boils down to the user requirements and the availability of wired infrastructure and WAN services.
If you contemplate a LAN extension, the link between the 1400s can be configured as a VLAN trunk (802.1q encapsulation) if traffic from multiple VLANs must transit through it. Considering the outdoor nature of the 1400 bridge, power is supplied via a power injector that can be housed indoors closer to a power source. The injector is equipped with a 100BASE-T port for connection to a LAN and a pair of RG-6 coaxial cables that extend to the bridge. Both sets of cables (Cat 5 and the two coaxial) extend to up to 100 meters, allowing a bridge unit to be up to 200 meters from the connection to a LAN switch.
The 1400 series bridges implement the Wireless Security Suite from Cisco. Authentication is supported via 802.1x with LEAP, which provides for mutual authentication and dynamic per-user and per-session encryption keys. Data encryption is supported via WEP with 40- and 128-bit keys. Also supported is TKIP WEP, which offers PPK and MIC. In addition to the 1400 series bridges, Cisco offers the 350 series bridges, which include a workgroup bridge.
The 1200 Series Access Points
The Aironet 1200 series APs offer maximum design flexibility due to the following characteristics:
They are modular and can be configured in single or dual mode, meaning that radios supporting either the 802.11b/g or 802.11a can be installed in a single unit. Single-mode 1200s support up to 16 VLANs, whereas dual-mode 1200s support twice that.
They support mobile IP and QoS for wireless clients, such as 802.11b mobile phones, which might require subnet hopping.
They support varying transmit power and receive sensitivity settings that allow for customization of these settings as a function of topology. For example, lower settings might be most appropriate near areas such as parking lots or front lobbies, where visitors could more readily intercept the signals.
They offer extensive security support:
- Similar to the 1400 series bridges, security in the 1200s is implemented via the Cisco Wireless Security Suite.
- Authentication support is more extensive than in the 1400 series bridges and includes 802.1x and the associated EAPs (LEAP, PEAP, EAP-TLS, EAP-TTLS, and EAP-SIM).
- Local (directly on the AP) LEAP authentication support is available for up to 50 users, which means there is no need for a dedicated AAA server. You should verify IOS versions for which local LEAP or RADIUS support is available.
- Encryption is offered via WEP, with 40- and 128-bit keys and the TKIP enhancements to WEP that facilitate PPK and MIC.
- The 1200s also support the WPA security, which offers stronger encryption than WEP.
From the administrative perspective, the 1200s allow for the simultaneous configuration of up to 16 SSIDs. Various AP settings can be associated with each SSID, including the client authentication method, the VLAN number, the maximum number of clients for the SSID, and even the repeater mode. Being able to map the repeater mode to an SSID allows, for example, one SSID on a root AP to be allocated for an association with a repeater AP. The repeater mode mapping to an SSID also includes username and password, which can minimize the potential for a rogue repeater AP to gain an association with a legitimately installed AP.
The 802.11a AP comes with an integrated diversity patch and diversity omnidirectional antennae that provide two distinct coverage patterns. The coverage for the patch antenna extends up to 70 feet (approximately 21 meters) at 54 Mbps and up to 200 feet (approximately 61 meters) at 6 Mbps. The omnidirectional antenna coverage is a bit shorter (60 feet at 54 Mbps and 170 feet at 6 Mbps), but it is uniform in all directions.
The integrated diversity antennae address the issue of multipath distortion. For the 802.11b/g AP options, you have a choice in antenna selection depending on the coverage requirements. The 1200 series APs come with a 10/100BASE-T autosensing uplink and are manageable via CiscoWorks.
NOTE
In addition to the 1200 series, Cisco offers the 1100 and 350 series APs. Review the specifications for each series to see which one best meets a customer's WLAN requirements.
The Aironet Antennae
Cisco offers a variety of antennae for its Aironet series products in support of all of the 802.11 physical layer standards. If an antenna is not already integrated with a product, the choice of antenna should be driven by the following criteria:
Application environment
Gain
Direction
Style
Physical size
Mounting method
Appearance
Table 6-2 summarizes the key characteristics of the Cisco Aironet antennae. Remember that you should always consult data sheets for all of the specific antenna characteristics.
| Antenna Characteristic | Antenna Characteristic Values |
|---|---|
| Gain | 2.2–21 dBi for 2.4-GHz bands, and 5–28 dBi for 5-GHz bands |
| Direction | Directional, omnidirectional, diversity omnidirectional |
| Polarization | Linear vertical, linear horizontal |
| Style | Dipole, patch, sector, yagi, dish |
| Frequencies | 2.4–2.484 GHz for 802.11b and 802.11g
UNII-1 (5.15–5.25 GHz) UNII-2 (5.25–5.35 GHz) UNII-3 (5.725–5.825 GHz) for 802.11a in the United States |
The Aironet Clients
Cisco Aironet clients include the 5-GHz LAN client adapter and the 350 series 802.11b compliant adapter. The 5-GHz adapter features a CardBus Type II form factor and operates in the two lower UNII bands. Security support on the authentication side includes 802.1x with LEAP, PEAP, EAP-TLS, and EAP-SIM. Encryption support includes static and dynamic WEP with 40- and 128-bit keys as well as WEP with TKIP. The 5-GHz adapters are well suited for any deployment in which the 1200 series 802.11a APs are installed.
The 350 series client adapters feature PC Card and PCI form factors and support the same security features as their 5-GHz siblings. Both types of adapters support drivers for many of the common operating systems, including versions of Windows, Mac OS, disk operating system (DOS), and Linux.
Other wireless clients from Cisco besides the Aironet series include the 7920 mobile IP phone, which works well with the Aironet 802.11b infrastructure, as well as clients available through the Linksys product line.