87 Chapter 4 – Wireless LAN Infrastructure Devices antennas and even accessories for mounting detachable antennas to the laptop or desktop case with Velcro. There are two major manufacturers of radio chipsets that make up the heart of the very popular 802.11b PC and CF cards: Agere Systems (formerly Lucent Technologies) and Intersil. Atheros is the first to mass-produce chip sets for the 802.11a standard that uses the 5 GHz UNII frequency bands. These manufacturers sell their chipsets to the PC and CF radio card manufacturers (the wireless LAN hardware manufacturing companies) who use the radios in their product lines. Compact Flash Cards, more commonly known as “CF cards”, are very similar to wireless PC cards in that they have the same functionality, but CF cards are much smaller and typically used in PDAs. Wireless CF cards draw very little power and are about the size of a matchbook. Wireless Ethernet & Serial Converters Ethernet and serial converters are used with any device having Ethernet or legacy 9-pin serial ports for the purpose of converting those network connections into wireless LAN connections. When you use a wireless Ethernet converter, you are externally connecting a wireless LAN radio to that device with a category 5 (Cat5) cable. A common use of wireless Ethernet converters is connection of an Ethernet-based print server to a wireless network. Serial devices are considered legacy devices and are rarely used with personal computers. Serial converters are typically used on old equipment that uses legacy serial for network connectivity such as terminals, telemetry equipment, and serial printers. Many times manufacturers will sell a client device that includes both a serial and Ethernet converter in the same enclosure. These Ethernet and serial converter devices do not normally include the PC card radio. Instead, the PC card must be purchased separately and installed in the PCMCIA slot in the converter enclosure. Ethernet converters in particular allow administrators to convert a large number of wired nodes to wireless in a short period of time. Configuration of Ethernet and serial converters varies. In most cases, console access is provided via a 9-pin legacy serial port. Figure 4.13 shows an example of an Ethernet and serial converter. FIGURE 4.13 A sample Ethernet and serial converter CWNA Study Guide © Copyright 2002 Planet3 Wireless, Inc. Chapter 4 – Wireless LAN Infrastructure Devices 88 USB Adapters USB clients are becoming very popular due to their simple connectivity. USB client devices support plug–n-play, and require no additional power other than what is delivered through the USB port on the computer. Some USB clients utilize modular, easily removable radio cards and others have a fixed internal card that cannot be removed without opening the case. When purchasing a USB client device, be sure you understand whether or not the USB adapter includes the PC card radio. In cases of a USB adapter that requires a PC card, it is recommended, although not always required, that you use the same vendor’s equipment for both the adapter and the PC card. Figure 4.14 shows an example of a USB client. FIGURE 4.14 A sample USB client PCI & ISA Adapters Wireless PCI and ISA are installed inside a desktop or server computer. Wireless PCI devices are plug–n–play compatible, but may also only come as an “empty” PCI card and require a PC card to be inserted into the PCMCIA slot once the PCI card is installed into the computer. Wireless ISA cards will likely not be plug-n-play compatible and will require manual configuration both via a software utility and in the operating system. Since the operating system cannot configure ISA devices that aren’t plug-n-play compatible, the administrator must make sure the adapter’s setting and those of the operating system match. Manufacturers typically have separate drivers for the PCI or ISA adapters and the PC card that will be inserted into each. As with USB adapters, it is recommended that you use the same vendor’s equipment for the PCI/ISA adapters and the PC card. Figure 4.15 shows an example of a PCI adapter with a PC card inserted. CWNA Study Guide © Copyright 2002 Planet3 Wireless, Inc. 89 Chapter 4 – Wireless LAN Infrastructure Devices FIGURE 4.15 A sample PCI Adapter Configuration and Management There are two steps to installing wireless LAN client devices: 1. Install the drivers 2. Install manufacturer’s wireless utilities Driver Installation The drivers included for cards are installed the same way drivers for any other type of PC hardware would be. Most devices (other than ISA adapters) are plug-n-play compatible, which means that when the client device is first installed, the user will be prompted to insert the CD or disks containing the driver software into the machine. Specific steps for device installation will vary by manufacturer. Be sure to follow the instruction manuals for your specific brand of hardware. ! When purchasing client devices, make sure the drivers are included for the specific operating system in which you will be installing the hardware. Serial & Ethernet converters require no special drivers to work; however, wireless LAN client utilities can still be installed and utilized. Manufacturer Utilities Some manufacturers offer a full suite of utilities and others simply provide the user with the most basic means of connectivity. A robust set of utilities might include:  Site Survey tools (Covered in Chapter 11, Site Survey Fundamentals)  Spectrum Analyzer  Power and speed monitoring tools  Profile configuration utilities  Link status monitor with link testing functionality CWNA Study Guide © Copyright 2002 Planet3 Wireless, Inc. Chapter 4 – Wireless LAN Infrastructure Devices 90 Site survey tools can include many different items that allow the user to find networks, identify MAC addresses of access points, quantify signal strengths and signal-to-noise ratios, and see interfering access points all at the same time during a site survey. Spectrum analyzer software has many practical uses including finding interference sources and overlapping wireless LAN channels in the immediate area around your wireless LAN. Power output and speed configuration utilities and monitors are useful for knowing what a wireless link is capable of doing at any particular time. For example, if a user were planning on transferring a large amount of data from a server to a laptop, the user may not want to start the transfer until the wireless connection to the network is 11 Mbps instead of 1 Mbps. Knowing the location of the point at which throughput increases/decreases is valuable for increasing user productivity. Profile configuration utilities ease administration tasks considerably when changing from one wireless network to another. Instead of manually having to reconfigure all of the wireless client’s settings each time you change networks, you may configure profiles for each wireless network during the initial configuration of the client device to save time later. Link status monitor utilities allow the user to view packet errors, successful transmissions, connection speed, link viability, and many other valuable parameters. There is usually a utility for doing real-time link connectivity tests so that, for example, an administrator would be able to see how stable a wireless link is while in the presence of heavy RF interference or signal blockage. Common Functionality Manufacturers' utilities vary greatly in their functionality, but share a common set of configurable parameters. Each of these parameters is discussed in detail in this book.  Infrastructure mode / Ad Hoc mode  SSID (a.k.a. Network Name)  Channel (if in ad hoc mode)  WEP Keys  Authentication type (Open System, Shared Key) Wireless Residential Gateways A wireless residential gateway is a device designed to connect a small number of wireless nodes to a single device for Layer 2 (wired and wireless) and Layer 3 connectivity to the Internet or to another network. Manufacturers have begun combining the roles of access points and gateways into a single device. Wireless residential gateways usually include a built-in hub or switch as well as a fully configurable, Wi-Fi compliant access point. The WAN port on a wireless residential gateway is the Internet-facing Ethernet port that may be connected to the Internet through one of the following: CWNA Study Guide © Copyright 2002 Planet3 Wireless, Inc. 91 Chapter 4 – Wireless LAN Infrastructure Devices  Cable modem  xDSL modem  Analog modem  Satellite modem Figure 4.16 shows an example of a wireless residential gateway, while Figure 4.17 illustrates where a wireless residential gateway is used on a wireless LAN. FIGURE 4.16 A sample wireless residential gateway FIGURE 4.17 A wireless residential gateway installed on a network Wireless Residential Gateway Internet Cable/DSL Modem Common Options Because wireless residential gateways are becoming increasingly popular in homes of telecommuters and in small businesses, manufacturers have begun adding more features to these devices to aid in productivity and security. Common options that most wireless residential gateways include are:  Point-to-Point Protocol over Ethernet (PPPoE)  Network Address Translation (NAT)  Port Address Translation (PAT) CWNA Study Guide © Copyright 2002 Planet3 Wireless, Inc. Chapter 4 – Wireless LAN Infrastructure Devices 92  Ethernet switching  Virtual Servers  Print Serving  Fail-over routing  Virtual Private Networks (VPNs)  Dynamic Host Configuration Protocol (DHCP) Server and Client  Configurable Firewall This diverse array of functionality allows home and small office users to afford an all-in- one single device solution that is easily configurable and meets most business needs. Residential gateways have been around for quite some time, but recently, with the extreme popularity of 802.11b compliant wireless devices, wireless was added as a feature. Wireless residential gateways have all of the expected SOHO-class access point configuration selections such as WEP, MAC filters, channel selection, and SSID. Configuration and Management Configuring and installing wireless residential gateways generally consists of browsing to the built-in HTTP server via one of the built-in Ethernet ports and changing the user- configurable settings to meet your particular needs. This configuration may include changing ISP, LAN, or VPN settings. Configuration and monitoring are done in similar fashion through the browser interface. Some wireless residential gateways units support console, telnet, and USB connectivity for management and configuration. The text-based menus typically provided by the console port and telnet sessions are less user-friendly than the browser interface, but adequate for configuration. Statistics that can be monitored may include items such as up-time, dynamic IP addresses, VPN connectivity, and associated clients. These settings are usually well marked or explained for the non- technical home or home office user. ! When you choose to install a wireless residential gateway at your home or business, be aware that your ISP will not provide technical support for getting your unit connected to the Internet unless they specifically state that they will. ISPs will usually only support the hardware that you have purchased from them or that they have installed. This lack of service can be especially frustrating to the non-technical user who must configure the correct IP addresses and settings in the gateway unit to get Internet access. Your best source of support for installing these devices is the manual provided with the device or someone who has already successfully installed similar units and can provide free guidance. Wireless residential gateways are so common now that many individuals that consider themselves non-technical have gained significant experience installing and configuring them. Enterprise Wireless Gateways An enterprise wireless gateway is a device that can provide specialized authentication and connectivity for wireless clients. Enterprise wireless gateways are appropriate for large- CWNA Study Guide © Copyright 2002 Planet3 Wireless, Inc. 93 Chapter 4 – Wireless LAN Infrastructure Devices scale wireless LAN environments providing a multitude of manageable wireless LAN services such as rate limiting, Quality of Service (QoS), and profile management. It is important that an enterprise wireless gateway device needs to have a powerful CPU and fast Ethernet interfaces because it may be supporting many access points, all of which send traffic to and through the enterprise wireless gateway. Enterprise wireless gateway units usually support a variety of WLAN and WPAN technologies such as 802.11 standard devices, Bluetooth, HomeRF, and more. Enterprise wireless gateways support SNMP and allow enterprise-wide simultaneous upgrades of user profiles. These devices can be configured for hot fail-over (when installed in pairs), support of RADIUS, LDAP, Windows NT authentication databases, and data encryption using industry- standard VPN tunnel types. Figure 4.18 shows an example of an enterprise wireless gateway, while Figure 4.19 illustrates where it is used on a wireless LAN. FIGURE 4.18 A sample enterprise wireless gateway FIGURE 4.19 An enterprise wireless gateway installed on a network C o r p o r a t e N e t w o r k Server Server Firewall Internet Enterprise Gateway Authentication technologies incorporated into enterprise wireless gateways are often built into the more advanced levels of access points. For example, VPN and 802.1x/EAP connectivity are supported in many brands of enterprise level access points. Enterprise wireless gateways do have features, such as Role-Based Access Control (RBAC), that are not found in any access points. RBAC allows an administrator to CWNA Study Guide © Copyright 2002 Planet3 Wireless, Inc. Chapter 4 – Wireless LAN Infrastructure Devices 94 assign a certain level of wireless network access to a particular job position in the company. If the person doing that job is replaced, the new person automatically gains the same network rights as the replaced person. Having the ability to limit a wireless user's access to corporate resources, as part of the "role", can be a useful security feature. Class of service is typically supported, and an administrator can assign levels of service to a particular user or role. For example, a guest account might be able to use only 500 kbps on the wireless network whereas an administrator might be allowed 2 Mbps connectivity. In some cases, Mobile IP is supported by the enterprise wireless gateway, allowing a user to roam across a layer 3 boundary. User roaming may even be defined as part of an enterprise wireless gateway policy, allowing the user to roam only where the administrator allows. Some enterprise wireless gateways support packet queuing and prioritization, user tracking, and even time/date controls to specify when users may access the wireless network. MAC spoofing prevention and complete session logging are also supported and aid greatly in securing the wireless LAN. There are many more features that vary significantly between manufacturers. Enterprise wireless gateways are so comprehensive that we highly recommend that the administrator take the manufacturer's training class before making a purchase so that the deployment of the enterprise wireless gateway will go more smoothly. Consultants finding themselves in a situation of having to provide a security solution for a wireless LAN deployment with many access points that do not support advanced security features might find enterprise wireless gateways to be a good solution. Enterprise wireless gateways are expensive, but considering the number of management and security solutions they provide, usually worth the expense. Configuration and Management Enterprise wireless gateways are installed in the main the data path on the wired LAN segment just past the access point(s) as seen in Figure 4.19. Enterprise wireless gateways are configured through console ports (using CLI), telnet, internal HTTP or HTTPS servers, etc. Centralized management of only a few devices is one big advantage of using enterprise wireless gateways. An administrator, from a single console, can easily manage a large wireless deployment using only a few central devices instead of a very large number of access points. Enterprise wireless gateways are normally upgraded through use of TFTP in the same fashion as many switches and routers on the market today. Configuration backups can often be automated so that the administrator won't have to spend additional management time backing up or recovering from lost configuration files. Enterprise wireless gateways are mostly manufactured as rack-mountable 1U or 2U devices that can fit into your existing data center design. CWNA Study Guide © Copyright 2002 Planet3 Wireless, Inc. 95 Chapter 4 – Wireless LAN Infrastructure Devices Key Terms Before taking the exam, you should be familiar with the following terms: bridge mode configurable firewall converters detachable antenna Dynamic Host Configuration Protocol (DHCP) Server and Client Ethernet switching fail-over routing modular cards Network Address Translation (NAT) Point-to-Point Protocol over Ethernet (PPPoE) Port Address Translation (PAT) portal print serving profiles repeater mode root mode SNMP wired connectivity variable output USB Virtual Private Networks (VPNs) virtual servers CWNA Study Guide © Copyright 2002 Planet3 Wireless, Inc. Chapter 4 – Wireless LAN Infrastructure Devices 96 Review Questions 1. Why would it not be a good idea to have a number of access points in repeater mode in series? Choose all that apply. A. Throughput would be reduced to unacceptable levels B. The access points would all be required to be physically connected to the network C. Data corruption can occur over the series of hops back to the root access point D. Legacy serial devices would not be able to communicate with the root access point 2. You are installing a wireless LAN in a factory, and the laptop client computers have no USB support. Which one of the following client devices could be used as a stand-alone client connection to the wireless LAN? A. ISA adapter B. PCI adapter C. PCMCIA card D. Ethernet converter 3. You need to connect two wired networks together that currently share no network connectivity between them. Using only access points to connect the networks, what mode would the access points need to be placed in? A. Root mode B. Repeater mode C. Bridging mode 4. When an access point connects to another access point wirelessly for the purpose of extending the wireless segments to client out of range of the access point connected to the wired segment, the access point not connected to the wired LAN segment is in ______ mode. A. Root B. Repeater C. Bridge 5. Wireless bridges are used for which of the following functions? Choose all that apply. A. Connecting mobile users to the wired LAN B. Point-to-multipoint configurations C. Building-to-building connectivity D. Wireless security CWNA Study Guide © Copyright 2002 Planet3 Wireless, Inc. [...]... wireless LAN radios are half duplex The same radios used for client connectivity are used for access points, bridges, and workgroup bridges CWNA Study Guide © Copyright 2002 Planet3 Wireless, Inc Chapter 4 – Wireless LAN Infrastructure Devices 102 20 D A USB adapter connects a computer’s USB port to a wireless network using a standard PCMCIA radio (whether internally fixed or externally modular) CWNA. .. quick reference guide for beamwidths Antenna Type Horizontal Beamwidth (in degrees) Vertical Beamwidth (in degrees) 360 Ranges from 7-80 Patch/Panel Ranges from 30-180 Ranges from 6-90 Yagi Ranges from 30-78 Ranges from 14- 64 Parabolic Dish Ranges from 4- 25 Ranges from 4- 21 Omni-directional CWNA Study Guide © Copyright 2002 Planet3 Wireless, Inc Chapter 5 – Antennas and Accessories 1 14 Selecting an... between the antenna and access point allow the administrator to protect the access point against weather and theft CWNA Study Guide © Copyright 2002 Planet3 Wireless, Inc 101 Chapter 4 – Wireless LAN Infrastructure Devices 10 C Wireless ISA devices do not support plug-n-play functionality, and therefore require manual configuration Legacy 9-pin serial wireless client devices likewise do not support... Access point B Wireless workgroup bridge C Enterprise wireless gateway D Wireless residential gateway 8 A company has hired you to recommend wireless LAN equipment that will allow them to place limits on the bandwidth used by each of their wireless users Which one of the following devices would you recommend? A Access point B Wireless workgroup bridge C Enterprise wireless gateway D Wireless residential... Client or VPN Client Passthrough 14 Which of the following are wired connectivity options that a wireless bridge can include? Choose all that apply A 10baseTx B 10baseFL C 10/100baseTx D 1000baseSX E 100baseFx 15 A workgroup bridge is a(n) device A Client B Infrastructure C Gateway D Antenna CWNA Study Guide © Copyright 2002 Planet3 Wireless, Inc 99 Chapter 4 – Wireless LAN Infrastructure Devices... the access point 20 A USB adapter is used with which type of wireless LAN device? A Gateway B Access point C Bridge D Client E Converter CWNA Study Guide © Copyright 2002 Planet3 Wireless, Inc Chapter 4 – Wireless LAN Infrastructure Devices 100 Answers to Review Questions 1 A, C When an access point is used in repeater mode, throughput of the wireless connection to clients is significantly reduced due... purpose of the following wireless LAN accessories and explain how to install, configure, and manage them Power over Ethernet devices Amplifiers Attenuators Lightning arrestors RF connectors and cables RF splitters CWNA Study Guide © Copyright 2002 Planet3 Wireless, Inc Accessories Chapter 5 – Antennas and Accessories 1 04 In the previous chapter, we discussed the many different pieces of wireless LAN equipment... essential to being able to build a functional wireless LAN Power over Ethernet (PoE) has become an important factor in today's wireless networks spawning new product lines and new standards PoE technology will be discussed along with the different types of PoE equipment that can be used to deliver power to a PoEenabled device CWNA Study Guide © Copyright 2002 Planet3 Wireless, Inc 105 Chapter 5 – Antennas... wired stations to the wireless network via standard wired Ethernet ports that are already installed in the computer Serial converters are used to connect stations that have no network connectivity or have legacy serial network connectivity to the wireless network via the standard 9-pin serial (COM) port 18 A A portal is a device that connects dissimilar media types such as 802.11 wireless and 802.3 Ethernet,... calculations Path Loss represents the single greatest source of loss in a wireless system Below is the formula for Path Loss 4 d  PathLoss = 20LOG10  {dB}  λ  You will not be tested on the Path Loss formula in the CWNA exam, but it is provided for your administrative reference CWNA Study Guide © Copyright 2002 Planet3 Wireless, Inc 115 Chapter 5 – Antennas and Accessories The 6dB Rule Close . externally modular). CWNA Study Guide © Copyright 2002 Planet3 Wireless, Inc. CWNA Study Guide © Copyright 2002 Planet3 Wireless, Inc. Antennas and Accessories CWNA Exam Objectives. large- CWNA Study Guide © Copyright 2002 Planet3 Wireless, Inc. 93 Chapter 4 – Wireless LAN Infrastructure Devices scale wireless LAN environments providing a multitude of manageable wireless. Building-to-building connectivity D. Wireless security CWNA Study Guide © Copyright 2002 Planet3 Wireless, Inc. 97 Chapter 4 – Wireless LAN Infrastructure Devices 6. Properly aligning two wireless bridges will