Chapter 9: Wireless Network Design Considerations (Part04)

Summary

In this chapter, you learned about the Cisco UWN architecture and wireless design principles. The following topics were explored:

• An introduction to RF theory, including phenomena affecting RF signals, RF signal calculations, and types of RF antennas

• The 802.11 standards, including the 802.11a/b/g half-duplex standards for wireless communication

• WLAN components, including the differences between autonomous and lightweight APs

• WLAN security, including authentication and encryption

• The Cisco UWN, including lightweight APs, WLCs, and the WCS management application

• LWAPP operation between the lightweight APs and WLCs, in Layer 2 or Layer 3 mode

• The terminology related to and operation of WLCs, including how lightweight APs discover and join with WLCs

• Mobility, the capability of end devices to move to new locations and remain networked, and roaming, when a wireless client moves its association from one AP and reassociates to another AP within the same SSID

• The real-time RRM in the Cisco UWN, which continuously analyzes the existing RF environment and automatically adjusts the AP power and channel configurations

• The RF site survey process and its importance in the design process

• Controller redundancy design, both dynamic and the recommended deterministic redundancy with predefined primary, secondary, and tertiary controllers

• Design considerations for using lightweight APs and WLCs in various scenarios, including for guest services, outdoor wireless networks, campus wireless networks, and branch wireless networks

References

For additional information, see the following resources:

• Cisco Systems, Inc., Enterprise Mobility 3.0 Design Guide, http://www.cisco.com/univercd/cc/td/doc/solution/emblty30.pdf

• Cisco Systems, Inc., Cisco UWN home page, http://www.cisco.com/go/unifiedwireless/

• Cisco Systems, Inc., Cisco Wireless LAN Controller Configuration Guide, Release 4.0, http://www.cisco.com/en/US/products/ps6366/products_configuration_guide_book09186a008082d572.html

• Cisco Systems, Inc., Cisco Wireless LAN Controller Configuration Guide, Release 4.1, http://www.cisco.com/en/US/products/ps6366/products_configuration_guide_chapter09186a008082d712.html#wp1102312

• Cisco Systems, Inc., Deploying Cisco 440X Series Wireless LAN Controllers, http://www.cisco.com/en/US/products/ps6366/prod_technical_reference09186a00806cfa96.html

• Cisco Systems, Inc., Cisco Compatible Client Devices, http://www.cisco.com/web/partners/pr46/pr147/partners_pgm_partners_0900aecd800a7907.html

• Cisco Systems, Inc., Cisco Wireless Control System home page, http://www.cisco.com/en/US/products/ps6305/index.html

• Cisco Systems, Inc., Cisco Outdoor Wireless Network Solution home page, http://www.cisco.com/en/US/netsol/ns621/networking_solutions_package.html

• Cisco Systems, Inc., Achieving Business Goals and Enhancing Customer Relationships with a Secure Guest Access Wi-Fi Network, http://www.cisco.com/en/US/products/ps6366/products_white_paper0900aecd8047180a.shtml

• Cisco Systems, Inc., Cisco 4400 Series Wireless LAN Controllers, Cisco Centralized Wireless LAN Software Release 3.0, http://www.cisco.com/en/US/products/ps6366/prod_bulletin0900aecd802d2742.html

• Cisco Systems, Inc., Radio Resource Management Under Unified Wireless Networks, http://www.cisco.com/en/US/tech/tk722/tk809/technologies_design_guide09186a008072c759tech_note09186a008072c759.shtml

Case Study: ACMC Hospital UWN Considerations

This case study is a continuation of the ACMC Hospital case study introduced in Chapter 2, “Applying a Methodology to Network Design.”

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Case Study General Instructions

Use the scenarios, information, and parameters provided at each task of the ongoing case study. If you encounter ambiguities, make reasonable assumptions and proceed. For all tasks, use the initial customer scenario and build on the solutions provided thus far.

You can use all documentation, books, white papers, and so on. In each step, you act as a network design consultant. Make creative proposals to accomplish the customer’s business needs. Justify your ideas when they differ from the provided solutions. Use any design strategies you feel are appropriate. The final goal of each case study is a paper solution.

Appendix A, “Answers to Review Questions and Case Studies,” provides a solution for each step based on assumptions made. There is no claim that the provided solution is the best or only solution. Your solution might be more appropriate for the assumptions you made. The provided solution helps you understand the author’s reasoning and allows you to compare and contrast your solution.

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In this case study you develop a high-level UWN design for the ACMC hospital network. A site survey is customarily required to determine RF propagation characteristics, select AP locations and antennas, look for interference (possibly a major factor in hospitals), and so forth. Hospitals also might have areas where radio signals would interfere with critical equipment; such areas must be protected from wireless AP signals. These specific hospital details are outside the scope of this book, but obviously they would have to be considered in a real hospital.

Assume that the site survey has been done, the results of which are summarized in Table 9-8. No sources of interference or RF prohibitions were discovered. For this design, assume that the wireless devices can be supported by the existing Ethernet ports. Notice that wireless coverage in the cafeteria on floor 1 of Main Building 1 has been added. The required ports in the remote clinics have also been added. The ACMC CIO has indicated no desire to implement any outdoor wireless support at this time.

Table 9-8: ACMC Hospital RF Site Survey Results
Open table as spreadsheet

Building	Port Counts	Access Point Requirements	Total Number of APs Required
Main Building 1	150 per floor, 7 floors (plus server farm)	8 per floor, 7 floors (including the cafeteria) 4 in the server farm (for administrator convenience)	60
Main Building 2	150 per floor, 7 floors	8 per floor, 7 floors	56
Children’s Place	120 per floor, 3 floors	6 per floor	18
Buildings A–D	20	1 per building, 4 buildings	4
Buildings E–J	40	2 per building, 6 buildings	12
Buildings K–L	80	4 per building, 2 buildings	8
Remote clinic 1	48	3	3
Remote clinics 2, 3	24	1 per building, 2 buildings	2
Remote clinics 4, 5	16	1 per building, 2 buildings	2
Total			165

Complete the following steps:

Step 1	Determine where to place controllers, how many of them to use, and which models to use. How will LWAPP WLC discovery be done? Justify your choices.
Step 2	The hospital wants to separate wireless traffic based on its three staff organizations: Financial, Medical, and Support. The intent is to enforce compliance with the U.S. Health Insurance Portability and Accountability Act (HIPAA) by allowing staff to authenticate to only the appropriate SSID based on the type of access they need. How does this affect your wireless design? What could you do to enforce the HIPAA access restrictions?
Step 3	What IP addressing scheme will you use to support the WLANs? How will you modify or extend the IP addressing scheme to the various wireless groups?
Step 4	What will your mobility group(s) be?
Step 5	How will wireless for the remote clinics be handled?
Step 6	How will secure guest wireless access be supported?