Wireless Architecture and Design
This chapter covers the following topics that you need to master for the CCNP BCMSN exam:
- WLAN Security—This section presents an overview of the various methods for protecting a WLAN. These methods can be used to authenticate potential wireless clients and users, as well as to secure the data passing over the wireless medium.
- Wireless Client Operation—This section explains the Cisco Compatible Extensions program and how it is used to find wireless hardware with compatible feature sets.
- AP Association and Roaming—This section covers the process that wireless clients and access points use to form associations or logical connections. As wireless clients become mobile, their associations can be moved to other access points. This forms the basis of client roaming.
- Cell Layout and Channel Usage—This section discusses the theory behind sizing and positioning access points so that they can work together to cover a large area. Part of this layout process is the assignment of RF channels and their distribution over the access point population.
"Do I Know This Already?" Quiz
The purpose of the "Do I Know This Already?" quiz is to help you decide what parts of this chapter to use. If you already intend to read the entire chapter, you do not necessarily need to answer these questions now.
The quiz, derived from the major sections in the "Foundation Topics" portion of the chapter, helps you determine how to spend your limited study time.
Table 18-1 outlines the major topics discussed in this chapter and the "Do I Know This Already?" quiz questions that correspond to those topics.
Table 18-1. "Do I Know This Already?" Foundation Topics Section-to-Question Mapping
Foundation Topics Section
Questions Covered in This Section
Wireless Client Operation
AP Association and Roaming
Cell Layout and Channel Usage
- If WPA or WPA2 is used as a wireless security suite, which one of the following represents a feature that is not offered in other wireless security methods?
- Virus mitigation
- Packet authentication
- Strong password policy
- Session time limits
- If WPA is used, how often can the encryption keys be generated?
- One key per AP association
- One key per client session
- One key per packet
- One key per minute
- TKIP is a protocol that is used with WPA to do which one of the following functions?
- Negotiate static WEP keys
- Generate per-packet encryption keys
- Authenticate a wireless user
- Authenticate wireless packets
- Most wireless security methods use which one of the following as the authentication mechanism?
- Which one of the following is a security feature that is unique to WPA2?
- AES encryption
- 3DES encryption
- WEP encryption
- Token-based encryption
- Which one of the following can be used to verify feature compatibility between wireless devices?
- IEEE 802.11b
- IEEE 802.11e
- Which one of the following determines when a wireless client will roam from one AP to another?
- The current AP has a weak signal from the client and asks it to roam
- The next AP overhears the client and asks it to roam
- The client's roaming algorithm reaches a threshold
- The client loses its IP address
- Which one of the following is moved when a wireless client roams to a new AP?
- When a wireless client is actively roaming, which one of the following actions does it take?
- It listens for 802.11 beacons
- It listens for 802.11 Roam advertisements
- It sends an 802.11 Roam Request
- It sends an 802.11 Probe Request
- Wireless client roaming from AP to AP normally occurs at what layer of the OSI model?
- Layer 1
- Layer 2
- Layer 3
- Layer 4
- Which channels should be used across the 802.11b APs that are covering a floor of a building?
- 1, 2, 3
- 1, 3, 6
- 1, 3, 6, 11
- 1, 6, 11
- Any channel is fine
- When you are designing the AP channel layout for an area, which one of the following is the most important consideration?
- The number of channels is conserved
- APs in different areas use different channels
- Adjacent APs use nonoverlapping channels
- Clients are grouped into common channels
The answers to the "Do I Know This Already?" quiz are found in Appendix A, "Answers to Chapter 'Do I Know This Already?' Quizzes and Q&A Sections." The suggested choices for your next step are as follows:
- 10 or less overall score—Read the entire chapter. This includes the "Foundation Topics," "Foundation Summary," and "Q&A" sections.
- 11 or more overall score—If you want more review on these topics, skip to the "Foundation Summary" section and then go to the "Q&A" section at the end of the chapter. Otherwise, move to Chapter 19, "Cisco Unified Wireless Network."