Chapter 4. Supplementary and Complementary Services

Chapter 2, "Business Considerations" discussed the value of mobility in your organization and provided frameworks for identifying the specific areas where WLANs can be most beneficial. You learned about the mobilization of existing applications as well as applications that you can successfully enable and leverage when a WLAN is deployed.

Chapter 2 did not discuss all applications and services that a WLAN can enable. Although some applications and services are important in today's business environment, they are not critical for WLANs. Consider these as "nice-to-haves" instead of "must haves" in your WLAN.

This chapter introduces you to these supporting services. The chapter outlines what the benefits of these services are, why they are more challenging to make available, and which recommended practices should be considered for provisioning them.

The services under consideration can roughly be grouped into two sets:

• Supplementary WLAN services make use of the transport mechanism provided by WLANs to provision a higher-order application. Voice and video fall within this category.

• Complementary WLAN services extend the availability of the transport system at the device level. The accessibility of the WLAN is expanded to a larger user community or the WLAN is used for device-specific procedures. Guest WLAN access and RF location services are examples of complementary services.

The rationale for layering supplementary services onto your WLAN is that it increases the value of your WLAN for your user community. The transport medium becomes completely transparent to the user, and the entire application suite that is available on the wired networks is made available on the wireless network. The WLAN thus effectively mobilizes all your applications and users.

Regrettably, this mobilization is not always easy to achieve because some applications are substantially harder to transfer to a WLAN environment. For example, voice and video are real-time and latency sensitive applications that demand deterministic network transport. Chapter 1, "Introduction to Wireless LAN Technologies," revealed that WLANs are susceptible to many internal and external influences. The number of WLAN users, physical obstacles, and other devices that operate in the same frequency band all have an impact on throughput and latency. As such, it might seem like a dichotomy to plan to deploy voice and video applications on a WLAN. This chapter shows that this is not the case.

The situation for complementary services is slightly different. Because you will already have deployed a WLAN, you can extend its application to additional services, thereby increasing the value you derive from this technology. Many of today's organizations are characterized by a high degree of fluidity in terms of individuals visiting office locations. Customers, consultants, and temporary staff are all examples of people who come and go on a daily basis and who could benefit from basic Internet connectivity. Guest networks become a viable complementary WLAN service for this transient community because it provides public hotspot-like connectivity. This chapter covers the benefits and challenges related to supporting guest WLANs.

A final complementary service that this chapter discusses is WLAN location services, which use the WLAN to determine the physical location of WLAN-connected devices. This chapter concludes by covering some of the benefits of location services as well as common implementation considerations.