Vendor Specific Topology Extensions

The vendor-specific topology extensions are an enablement of additional network functionality by way of vendor-defined protocols, devices, and topologies. In this section you will learn how workgroup bridges, wireless repeaters, outdoor wireless bridges, and wireless mesh networks through the use of wireless controllers can enhance the functionality and capability of your wireless deployment. You will most likely have times when you have an isolated network that needs access to the rest of the...

General Wireless Topologies

When you're talking about wireless topologies, there are a number of ways it could go. If you are talking about how your wireless network looks next to your wired network, you are most likely talking about a wireless local-area network (WLAN). The goal of a WLAN versus a wireless personal-area network (WPAN) is quite different. The following sections discuss the purpose of each network type, what they try to accomplish, and what types of wireless technologies you might encounter there. Figure...

Original 80211 Topologies

Although the previous sections discussed network topologies that you might encounter, it was a very general discussion. You also need to understand the original topologies, defined by the 802.11 committees, including the following The following sections give more details on these topologies. When two computers want to communicate directly with one another, they do so in the form of an ad hoc network. Ad hoc networks don't require a central device to allow them to communicate. Rather, one device...

Controller Terminology

Now that you have some understanding about the different types of controllers that are available, it is helpful to understand some of the terminology that goes along with them. The term interface, when related to a Cisco controller, is not the same as you would experience on a router. With Cisco routers, an interface can be a physical or logical (loopback) entity. With Cisco controllers, an interface is logical. It can include VLANs, which in turn have a port association. Some interfaces are...

LWAPP Layer 2 Transport Mode

When operating in Layer 2 mode, LWAPP has the following characteristics and require- Topic LWAPP communication between the AP and the WLC is in native, Layer 2 Ethernet frames. This is known as Layer 2 LWAPP mode. In Layer 2 LWAPP mode, although the APs might get an IP address via DHCP, all LWAPP communications between the AP and WLC are in Ethernet encapsulated frames, not IP packets. The APs must be on the same Ethernet network as the WLC. This means that Layer 2 mode is not very scalable....

Figure 112 AP States

The process begins with the discovery of a controller. Because the lightweight APs are by definition zero-touch when deployed, you should only need to plug them in and let them do the rest. On the back end, the part you do not see is a little more complex. The steps in this process, beginning with discovery, are as follows Step 1. The APs send LWAPP discovery request messages to WLCs. This is broadcast at Layer 2. Because Layer 3 mode is what you want to use, this should fail. Step 2. Upon...

WLAN Technologies and Topologies

When you work in a wireless network, you can encounter a number of technologies and deployment options. Sometimes your situation calls for a peer-to-peer connection, and other times you will want to connect to users who are in another room or on another floor, yet on the same network. In this chapter you will learn what these networks are and when they are appropriate. You will also look at which types of equipment are appropriate for certain situations and environments. Use the Do I Know This...

Determining Signal Strength Influences

Although it might seem hopeless to deploy a network that is susceptible to various forms of interference, you can fight back. To fight back, you need to know what tools are available out there for you to determine signal strength, noise levels, and potential sources of interference in the path. This section discusses these tools. To give you a little background, Augustin-Jean Fresnel was a French physicist and civil engineer who lived from 1788 to 1827. He correctly assumed that light moved in...

The CUWN Architecture

The Cisco Unified Wireless Network defines a total of five functional areas or interconnected 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 network. To illustrate how it all comes together, consider a Cisco wireless network. This type...

The Layer 3 Roaming Process

As with Layer 2 roaming, the goal of Layer 3 roaming is for a client to roam transparently. The difference is that you are working with multiple controllers on different subnets. The catch is that although the controllers are on different subnets, the user does not change IP addresses. Instead, the controllers tunnel the traffic back to the original controller. So it's a smoke-and-mirrors configuration. You are literally making the network believe that the user hasn't roamed. The two tunneling...

Using WCS Version 5x to Troubleshoot Clients

You can use WCS to troubleshoot wireless deployments. Use the Monitor > Client page to troubleshoot clients. You can see this page in Figure 20-6. When you use this tool, you get a Summary page with a list of problems and corresponding solutions. The page also has a log analysis and a detailed event history. You can use the alarms to troubleshoot. In the Clients Summary page, click the numerous alarms in the lower left to be taken to that Alarm page. Figure 20-6 shows several critical alarms.

The 80211 Protocol Family Overview

The IEEE helps to standardize wireless protocols. Those that you must be familiar with for the CCNA Wireless Exam are the 802.11 a b g and n protocols. These four IEEE standards define the wireless family that is used in almost all wireless LANS today. The standardization of wireless networking started with the original 802.11 protocol in 1997, and each protocol thereafter has simply added to the benefit of wireless technologies. This chapter looks at the 802.11 protocol families, their...

The 3750G WLC

The 3750-G Wireless LAN Controller, shown in Figure 10-9, is integrated into a switch. There are two assemblies the WS-C3750G-24PS-E and the AIR-WLC4402-*-K9. The two assemblies are connected to the SEPAPCB assembly, which has two Gigabit Ethernet links connecting through SFP cables and two GPIO control cables. The major benefits of this integration into the switching platform include the following Figure 10-9 Cisco 3750-G Series Wireless LAN Controller Figure 10-9 Cisco 3750-G Series Wireless...

Wireless Frame Headers

Each of the fields has been expanded so you can see it more clearly. It is beneficial to understand these fields and how they play a part in the sending and receiving of wireless frames. Type Subtype Data (0x20) Frame Control. 0*GA08 (Norma ) Version 0 Type Data frame (2) Subtype 0 Flags Oxfi DS status Frame from DS to a STA via AP(To DS 0 From DS 1) (Qx02) More Fragments This is the last fragment Retry Frame is being retransmitted ,.0 PWR MGT STA will stay up...

Connecting to a Standalone AP

Almost any AP that is capable of operating in both autonomous and lightweight mode ships in autonomous mode. You need to convert the device to lightweight mode if you plan to use it in that mode. Luckily, you can accomplish this conversion in two ways. You can get a Windows application called the Upgrade tool to do it, and you can get it done using the Cisco Wireless Control System (WCS). Either method accomplishes the same task it is simply a matter of what you prefer and what you have access...

Modulation Techniques and How They Work

In short, the process of modulation is the varying in a signal or a tone called a carrier signal. Data is then added to this carrier signal in a process known as encoding. Imagine that you are singing a song. Words are written on a sheet of music. If you just read the words, your tone is soft and does not travel far. To convey the words to a large group, you use your vocal chords and modulation to send the words farther. While you are singing the song, you encode the written words into a...

Wlan Rf Principles

In wireless technologies, you need to understand what influences act on wireless transmissions. This chapter reviews the characteristics of wireless transmissions and the influences that act on them, sometimes causing problems. Some of the material covered in the first section, Characteristics of Wireless Networks, is a review of information you learned in Chapter 1, Introduction to Wireless Networking Concepts. If you are comfortable with your knowledge of this information, you can just review...

DOATAP

AP-Priming is used for which of the following a. Prime an AP prior to bootup with complex algorithms b. Deliver a list of controllers to the AP using a hunting process and discovery algorithm c. Perform basic setup of controller configurations delivered to the AP d. Provision an AP over the air 7. Which of the following is not contained in a join response message b. Interfaces in the controller

How Bandwidth Is Achieved from RF Signals

To send data over the airwaves, the IEEE has developed the 802.11 specification, which defines half-duplex operations using the same frequency for send and receive operations on a WLAN. No licensing is required to use the 802.11 standards however, you must follow the rules that the FCC has set forth. The IEEE defines standards that help to operate within the FCC rules. The FCC governs not only the frequencies that can be used without licenses but the power levels at which WLAN devices can...

LWAPP Layer 3 Transport Mode

As previously mentioned, Cisco prefers Layer 3 LWAPP mode. This is because it is more scalable than Layer 2 LWAPP. Layer 3 LWAPP control and data messages are transported over the IP network in User Datagram Protocol (UDP) packets. Layer 3 LWAPP is supported on all Cisco WLC platforms and lightweight APs. The only requirement is established IP connectivity between the APs and the WLC. The LWAPP tunnel uses the IP address of the AP and the AP-Manager interface IP address of the WLC as endpoints....

Overview of the Small Business Communication System

The Cisco Mobility Express solution, seen in Figure 15-1, is either a standalone or a controller-based access point (AP) and a controller-based solution. Figure 15-1 Cisco Mobility Express Solution Figure 15-1 Cisco Mobility Express Solution Adapt to your level of sophistication You manage the solution through a configuration assistant software application. The Cisco Mobility Express solution is only a portion, however, of the Cisco Smart Business Communication System (SBCS). This SBCS includes...

Common Antenna Types

Paraboloic Dish Antenna Cisco Com

The two main types of antennas are directional and omnidirectional. In this section you will learn the difference between the two types and look at some of the antennas that Cisco offers. Both send the same amount of energy the difference is in how the beam is focused. To understand this, imagine that you have a flashlight. By twisting the head of the light, you can make the beam focus in a specific area. When the beam has a wider focus, it doesn't appear to be as bright. While you twist the...

Upgrading a Controller

Management tasks in the controller involve upgrading or downgrading images as well as managing configuration files. You can begin working with these files by verifying the version currently running on the controller. Figure 19-1 shows the MONITOR > Summary page, which indicates that the version of code on this particular controller is software version 4.1.192.17M (Mesh). 5.x is the current version of code, so you need to obtain the version you want to have loaded before performing the...

And How It Is Used

802.1x is an authentication standard defined by the IEEE. It has been used for some time on the wired side of networks, so it was a logical choice for wireless networks. At its most basic level, 802.1x is a method of opening or closing a port based on a condition. The condition here is that an AAA server has verified the client's identity. 802.1x is a framework that uses various EAP methods in its communication. Elaborating on the fact that the 802.1x has been used on wired networks for some...

Maps and APs in the WCS

Maps in the WCS are designed to give you a visual representation of the wireless network. Not only do maps help with monitoring after a deployment, but they help in the implementation and deployment process. You can use planning mode to determine how many APs you need in an area and where to place them. To access the maps, browse to Monitor > Maps. From here you can see a list of maps, as illustrated in Figure 18-10. You start by adding a building and then adding floors. After you have the...

Understanding the Different Lwapp Modes

LWAPP can operate in either Layer 2 LWAPP mode or Layer 3 LWAPP mode. The Layer 2 mode is considered out of date, and Cisco prefers and recommends Layer 3 mode. Layer 3 mode is the default LWAPP mode on most Cisco devices. At a high level, and after the AP has an IP address, the phases of LWAPP operation include Step 1. An AP sends an LWAPP discovery request message. This is a broadcast that is sent at Layer 2. Step 2. Assuming that a controller is operating in Layer 2 LWAPP mode, the wireless...

Managing Configurations

When working in the Cisco Unified Wireless Environment, you deal with a number of configuration files. You potentially have numerous controller configurations as well as AP configurations. When you're working with the controller, it's a good idea to save your configuration often. Clicking the Save Configuration link can save a controller's configuration. It is found in the top-right corner of the web interface, as shown in Figure 19-8. In addition to saving the configuration to NVRAM, you can...

Zig Bee

Many people have never heard of ZigBee, but it's a technology that is well-designed and very useful. ZigBee was developed by the ZigBee Alliance. It consists of small, low-power digital radios based on the IEEE 802.15.4 standard for wireless personal-area networks (WPAN), such as wireless headphones connecting to cell phones via short-range radio. If you look at the ZigBee Alliance home page at http www.zigbee.org, you'll likely notice that ZigBee relates much of its use to control and...

Key Topic

Figure 9-5 ARP Forwarded in LWAPP Frame Figure 9-5 ARP Forwarded in LWAPP Frame The LWAPP frame that travels from the AP to the WLC is traveling on a wired network. This brings forth the question, What happened to the 802.11 frame format LWAPP simply encapsulates the frame inside a 6-byte header. The new 6-byte header has the AP IP and MAC address as the source and the WLC IP and MAC address as the destination. Encapsulated inside of that header is the original 802.11 frame with the three MAC...

Monitoring with the Controller

As far as the management and monitoring of the network go, you have much power by way of the controller. The controller is a central point of intelligence that can give you valuable information regarding the network overall as well as specifics related to APs, clients, rogues, and more. The main login page of the controller provides an excellent starting point. The Controller Summary page is the first thing you see when you log in. At first glance, it might seem like a simple overview, but it...

Cisco Learning Network

Cisco provides a wide variety of CCNA wireless preparation tools at a Cisco Systems website called the Cisco Learning Network. The Cisco Learning Network includes Quick Learning Modules, interviews with Cisco's Portfolio Manager for Wireless Certifications, documents that give you a sneak peek of what's included in the Instructor-Led Training Course, and blogs and discussion forums to help you on your way. To use the Cisco Learning Network, you do not need a registered login at http www....

Wireless Attacks

It's not news that networks in general are constantly bombarded with attacks. Some of these attacks are unique to wireless networks, as is the case with management frame spoofing. With management frame spoofing, a rogue AP advertises an SSID known to the client in an attempt to get the client to connect to the rogue AP. Other attacks apply to both wired and wireless networks Reconnaissance attacks An attacker attempts to gain information about your network. Initially, the method of mitigating...

Mobility Anchors

With mobility anchors, also called guest tunneling or auto anchor mobility, all the client traffic that belongs to a WLAN (especially the Guest WLAN) is tunneled to a predefined WLC or set of controllers that are configured as an anchor for that specific WLAN. This feature helps restrict clients to a specific subnet and have more control over the user Figure 12-11 Mobility Anchor Configuration Figure 12-11 Mobility Anchor Configuration traffic. Normally what happens is that a client anchors to...

Configuring Tunneling

To begin the tunneling configuration, first you must decide which type of tunneling you will do. The default mode is asymmetric, and the controllers must match in their configuration. Select CONTROLLER > Mobility Management > Mobility Anchor Config. Figure 12-11 shows the resulting configuration page. This configuration page enables you to configure a Keep Alive Count and Keep Alive Interval. There also is a checkbox for symmetric mobility tunneling mode, which is not enabled by default....

Do I Know This Already Quiz

The Do I Know This Already quiz helps you determine your level of knowledge of this chapter's topics before you begin. Table 14-1 details the major topics discussed in this chapter and their corresponding quiz questions. Table 14-1 Do I Know This Already Section-to-Question Mapping Table 14-1 Do I Know This Already Section-to-Question Mapping Using the Express Setup and Express Security for Basic Configuration 1. A standalone AP has a console port. True or False 2. Which methods can be used to...

Connecting to the Controller

To begin configuring the controller, you need a connection to it. You can access the controller in more than one way however, this section focuses on creating a command-line interface (CLI) connection. After you have CLI access, you can observe the boot sequence and run though a basic configuration. Doing so provides an IP address that you can use later to browse to the HTML interface. You will be connecting to the serial interface, so you will use a DB9 serial cable. You will also need a...

Comparing the Cisco Mobility Express Architecture to the CUWN

When you compare the Cisco Mobility Express Architecture to the Cisco Unified Wireless Network, you will find that the model is similar however, the protocols are different. The Mobility Express solution does not use the full enterprise class version of LWAPP rather, it uses a subset of LWAPP. In addition, the Cisco 521 AP cannot communicate with CUWN wireless LAN controllers. Likewise, the Cisco 526 cannot communicate with APs from the 1100 series or higher. The 526 supports control of up to...

Wireless Standards and Regulatory Committees

Many people benefit from the availability of wireless Internet access as they travel to various parts of the world. Without regulatory committees and organizations to ensure the proper use and interoperability of equipment, it's likely that people could not connect from place to place. To ensure that certain rules governing the use of wireless RF are adhered to, numerous country-specific organizations and global committees monitor standards and usage. This chapter discusses some of them. The...

Using the CLI to Configure the Controller

To configure the Cisco Mobility Express solution, you need a console connection to the Cisco 526. You do not need to do anything on the AP because the controller takes care of it. After you have a console connection, you can power on the device and view the boot process. In Example 15-1, notice that if you press the Esc key, you are presented with multiple boot options. The normal selection is to run the primary image. Example 15-1 Booting the Cisco 526 Controller Booting Primary Image Press...

Adding Controllers to the WCS

To add controllers to the WCS, use the Configure tab. From there, you cannot only add controllers, but you can configure APs. You can also create templates here that allow the deployment of common configurations among multiple devices. To add controllers, browse to Configure > Controllers, as shown in Figure 18-3. The Configure Controllers page summarizes all the controllers in the WCS and allows you to add controllers. Using the Select a command drop-down (seen in Figure 18-3), select Add...

The 80211a Protocol

802.11a was ratified in 1999 and operates in the 5-GHz frequency range. This makes it incompatible with 802.11, 802.11b, and 802.11g, while avoiding interference from these devices in addition to microwaves, Bluetooth devices, and cordless phones. 802.11a had late-market adoption, so it is not as widely deployed as the 802.11b and g protocols. Another difference is that 802.11a supports anywhere from 12 to 23 nonoverlapping channels as opposed to the 3 nonoverlapping channels in 802.11b g....

Installing and Configuring the WCS

Topic The WCS has two deployment possibilities a Linux-based deployment and a Windows-based deployment. In large deployments, Cisco recommends the Linux-based deployment. The requirements for the Linux-based deployment are as follows Red Hat Enterprise ES AS Linux Release 4 (the Cisco WCS can be installed as a service under Linux) Intel Xeon Quad 3.15-GHz CPU Meeting these requirements allows for support of 3000 APs and 250 controllers and really cannot be stressed enough. If you want to be...

Understanding Mobility Groups

In simple terms, a mobility group is a setting on a controller that defines the controller as a member of a group. Other controllers would also be members of that group. These controllers share information about the clients that are roaming. In Figure 12-1, two controllers are in the same mobility group. They can exchange information about the client that is roaming. Figure 12-2 shows a network with three controllers. Controllerl and Controlled are in the same mobility group, and Controller3 is...

Client Misassociation

When a client connects to an AP, operating system utilities normally allow the client to save the SSID. In the future, when that SSID is seen again, the client can create a connection automatically. There is a possibility that clients will be unaware of the connection. If the SSID is being spoofed, the client could connect to a potentially unsafe network. Consider the following scenario. An attacker learns the SSID of your corporate network. Using this information, he sends beacons advertising...

AP name

Certificate payload (x.509) Session payload to set up the session values Test payload to see if jumbo frames can be used This join request message is sent using a predefined method consisting of the following steps Step 1. An AP chooses the primary controller (if primed). This can be defined in each AP and stored in flash to survive a reboot. Using the controller GUI, go to WIRELESS > Access Points > All APs > SelectedAp > Details, as seen in Figure 11-4. Step 2. Choose the secondary...

Cordless Phones

Cordless phones have been around as long as I can remember or at least since I was in junior high. Cordless phones sometimes operate in the wireless spectrum as WLANs, which can cause interference issues. Visit an electronics store, and you'll find some phones that operate at 2.4 GHz and others that operate at 5.8 GHz. This should be a consideration when you purchase cordless phones. If you have 802.11a deployed, a 2.4-GHz phone should suffice. If you have 802.11b g, you should avoid a phone...

Exam Preparation Tasks Review All the Key Concepts

Review the most important topics from this chapter, noted with the Key Topics icon in the outer margin of the page. Table 14-2 lists a reference of these key topics and the page number where you can find each one. Table 14-2 Key Topics for Chapter 14 Table 14-2 Key Topics for Chapter 14 Paragraph list in the section Accessing the AP in Autonomous Mode List of methods used to access the AP Paragraph list in the section Using the Express Setup and Express Security for Basic Configuration List of...

Frame Types

For the most part, all frames are going to have the same type of header. The difference is in the body of the frame. The body is more specific and indicates what the frame is all about. Table 7-2 shows some frame types. Contention Free End + Acknowledgment (CF-End +ACK) Announcement traffic indication message (ATIM) Each frame type merits its own discussion to follow. Management frames, as their name indicates, are used to manage the connection. In looking at a frame capture, the Type field...

Converting to LWAPP

Three methods you can use to convert the AP to lightweight mode are as follows Use the IOS to LWAPP conversion utility. This is an installable application that you can download from Cisco.com. Use the WCS. If you have a WCS, this method is probably preferred however, it is not covered as part of the CCNA wireless certification. As of July 2005, simply archive the image to the AP to convert it to LWAPP. The section that follows examines the IOS-to-LWAPP conversion. Converting to LWAPP Using the...

Configuring the Controller Using the Web Interface

Topic For this example, you build basic wireless connectivity. The process is as follows Build the controller interface. Create the WLAN and tie it to the interface. Building the controller interface is required because, as you might recall from the beginning of this chapter, the interface is a logical entity. It is not a physical port that you can touch, although the interface you create will end up having access to the network via one of the physical ports. After you have created the...

Using the CLI to Troubleshoot

Sometimes resolving the common issues is not easy and they require further research. In these cases, you can use the CLI or the GUI tool to gather additional information. From the CLI, you have a few options for troubleshooting. First, you can use show commands on the CLI to gain valuable information related to the operational status of the controller, the APs, and the clients. Many of these show commands are available in various pages of the GUI tool, as you will see in later sections of this...

Influences on Wireless Transmissions

Now that you clearly understand wireless transmissions and what is involved, it is a good time to discuss the influences on wireless signals. Some influences can stop a wireless signal from propagating altogether, whereas others might simply shorten the transmission distance. Either way, you should be aware of these factors so you can plan and adjust your deployment accordingly. In this section, you learn about the Free Path Loss model, absorption, reflection, scattering, multipath, refraction,...

Using the Controller Interface

The controller has several tools to help troubleshoot. From the controller interface, you can use controller logs, SNMP to alert administrators to current issues, and the Tech Support Pages. In the section Using the CLI to Troubleshoot, you looked at output of a client that was trying to associate. You can see a web interface equivalent to the show client summary command in Figure 20-1. Figure 20-1 Viewing the Client Summary Figure 20-1 Viewing the Client Summary Here you can gain information...

Using the Cisco Spectrum Expert

Cisco Spectrum Expert addresses the problem of RF interference in wireless networks. With Cisco Spectrum Expert, you can detect, classify, locate, and manually mitigate sources of wireless interference. The Cisco Spectrum Expert Wi-Fi is the industry-leading spectrum intelligence product for Wi-Fi networks. Cisco Spectrum Expert Wi-Fi offers complete visibility into the RF physical layer in the 2.4-GHz and 5-GHz frequencies, allowing for enhanced performance, security, and reliability of WLAN...

Wireless Traffic Flow and AP Discovery

It is not likely that in your everyday activity you will be following the flow of traffic. At least the hope is that you will not have to. On occasion, however, you will need to analyze the flow of traffic in troubleshooting network issues. For this reason and just so that you have a complete understanding of what is involved in wireless transmissions, you need to understand wireless traffic flow and the process of discovering an AP. In this chapter, you will learn how a client finds an AP,...