The preparation phase of your deployment is a critical initial step. Careful consideration of the issues at this early stage will greatly increase the probability of a smooth and successful deployment. The primary task associated with the preparation phase of the PPDIOO solution lifecycle is identifying and validating the business case. This was covered in detail in Chapter 2. Additional factors that require attention when you prepare your WLAN deployment include defining the breadth and scope of the WLAN and deciding how you will fund the project.
Generic solutions typically produce average results. By considering the topics defined in this section, you can proceed in a prepared manner with your goals and constraints clearly defined and
After you have defined your goal, you can
By clearly identifying and defining your position on these issues, you will provide a more
Breadth and Scope of Deployment
One of the first sets of decisions you should make when preparing to deploy an enterprise-class wireless LAN
You need to determine how large a footprint you want your WLAN to have. The business rationale you identify (as described in Chapter 2) will
Draw up a list of all
A key focal point should be the infrastructure requirements that a WLAN deployment
Table 3-1. Hierarchical Network Layers
Figure 3-2 illustrates the network layers.
Figure 3-2. Hierarchical Network Model
In a typical wired network, your users connect via the access layer switches, which are sometimes known as workgroup switches . In a WLAN, however, your users connect to the network via the wireless access points. Access points are considered edge devices, and they lie within the access layer, as you can see in Figure 3-3.
Figure 3-3. Access Layer
Don't confuse the terms "access layer" and "access points." The access layer is a conceptual
These concepts are important because when you deploy a WLAN, you are adding devices into your access layer and connecting them directly to your workgroup switches. Therefore, you must ensure that your workgroup switches have sufficient capacity for these access points. Typically they require a network port, power, and console access.
Because each access point requires an Ethernet port for connectivity, you must ensure that your network switches have sufficient port capacity to attach the AP to the rest of the network. Typically, this does not pose a problem in greenfield deployments. Deploying your WLAN in an established or mature networking environment, this becomes a significant consideration to address. Otherwise, you would have to budget
In summary, to ensure that your access points can establish connectivity, answer the following questions:
Electronic equipment requires electrical power. Generally speaking, you can power access points in two ways:
Powering the access points via AC is straightforward but requires that you provide AC outlets in the vicinity of the access point. This is often an expensive exercise that requires the use of certified electrical
Powering the access points via the Ethernet cables is achieved via Power over Ethernet (PoE). This technology has been standardized as IEEE 802.1af and employs a previously unused pair of wires in category 5 (or better) cables to provide power to a device. PoE is popular because it avoids the need to install expensive additional power cables at each location and helps reduce costs.
When determining your power requirements, answer the following questions:
When planning your WLAN, answer the following questions:
Many enterprises decide to physically locate the access points in the
Certain environments have stringent controls on what electrical equipment can be deployed in other areas. Examples include government or military installations, hazardous environments (mining, petroleum, gas,
In the United States, there are also national health and safety regulations to be considered, and local and national building standards. It is important for you to follow due diligence on potential environment or safety standard issues that are specific to your organization's context. Be sure to investigate and understand your obligations and ensure that your equipment complies with all relevant standards. The use of an
Safety and standards compliance are not the only environmental topics that can impact your planning phase. Simple issues such as ruggedness or waterproofing might also need to be considered. This is
Regulatory Restrictions or Requirements
As mentioned in Chapter 1, the regulations that apply to the use of 2.4-GHz and 5-GHz frequency ranges are not the same all over the world. At this stage, it is sufficient to note that you must take local and national regulations into account and plan accordingly. This is especially important if you are considering a large, transnational or global deployment because you might need to purchase different models for different countries.
Deployment Funding Strategies
There are many funding strategies for deploying wireless in an organization, including the following:
This section describes these common strategies along with their advantages and disadvantages. You learn more about funding strategies in Chapter 6, "Wireless LAN Deployment Considerations."
Centrally Funded Deployment
Centrally funded is perhaps the most common funding strategy. The entire cost is absorbed by a single entity; this can be the IT department, Finance, or the group responsible for business operations. In most small to medium deployments, this is the only model used.
Advantages of centrally funded deployment include
Disadvantages of centrally funded deployment include
Group-funded deployment strategies are those where a division, department, or sometimes regional section of an enterprise funds the deployment from its own budget. It either engages external professional
Advantages of group-funded deployment include the following:
Disadvantages of group-funded deployment include the following:
A client-funded strategy is simply one whereby the IT department of the enterprise is responsible for installing and managing the deployment but utilizes a charge-back mechanism to the
Client-funded deployments are usually based upon an installation charge per AP or
Advantages of client-funded deployment include
Disadvantages of client-funded deployment include
The subscription-based deployment strategy is also known as "pay as you go." In this model, the users or user groups pay a service fee for wireless network access. The subscription model ensures that you not only recover the costs associated with the service deployment but also recuperate ongoing support and maintenance costs.
This model is less common in most standard enterprise deployments but popular in environments where you have many different user types. Universities are a good example. The provision of wireless network access can be considered an added value service that the student body pays for on a per-user or per-class basis.
Advantages of subscription-funded deployment include the following:
Disadvantages of subscription-funded deployment include the following: