After completing this lab, you’ll be able to
In this lab you’ll have the opportunity to apply much of the information that you learned in this chapter by designing a highly available network topology. The lab is structured by first presenting a scenario that outlines the basic considerations that you’ll need to take into account when you design the network infrastructure. The rest of the lab is divided into exercises, each of which focuses on a particular design element. The lab focuses primarily on redundant components and paths, network subnetting, and namespace design. It’s only peripherally concerned with redundant services and the DHCP environment—with regard to how they apply to high availability—because the DHCP service and other services are made redundant though the use of clustering, which is discussed in greater detail in subsequent chapters. In addition, the lab doesn’t incorporate DNS fault tolerance because that’s implemented through Active Directory in order to ensure high availability. Active Directory is also discussed later in this book. As a result, the exercises are limited to the primary areas of focus, with the understanding that clustering solutions appear merely as placeholders at this phase of the design process and that clustering—along with Active Directory—will be incorporated into the network design later.
Before you begin this lab, you must be able to
Contoso, Ltd., is a new company that plans to create a Web site that provides immunization and prophylaxis information to international travelers. The site will serve two purposes. The first is to provide general information about individual countries/regions in terms of immunization and prophylaxis requirements and recommendations. The information will include specific details about legal requirements, paperwork, drugs, side effects, diseases, and any other information related to health issues when traveling in different parts of the world. Initially, the site will target English-speaking travelers from around the world and will include any destination for which information can be obtained. Income will be generated through site advertisements. The site’s second purpose is to provide a subscription-based service that maintains a record of where individuals have traveled, what immunizations and prophylaxis they received, and what risks they were exposed to. At any time, clients can know which vaccines or drugs they’ve taken and when. The information is also helpful if a person who develops symptoms after returning home needs to know what he or she may have been exposed to.
Because users must be able to access site information from any region in the world at any time of day, the site must be available around the clock. However, the company currently can support only one geographical location, so high availability must be designed into a single location and client records must be absolutely secure. The company has registered the name contoso.com with an Internet name authority.
You must design a network topology that meets the company’s requirements. For the purpose of this lab, your main concern is the Web portion of the network topology. You can assume that the secure part of the corporate network will be a typical Ethernet topology that’s connected to the Web topology through a router/firewall connection.
Your first step in designing the network topology is to design a system that contains redundant components, paths, and services. As stated above, redundant services are implemented as clusters, so you need only to indicate their placement in the design. You plan to use a multitiered topology and create a perimeter network to support the Web portion of the network design. In addition, you plan to use switches rather then hubs within the perimeter network. You’ll begin with a topology similar to the one in Figure 2.18.
You must now add redundancy to the network topology.
Figure 2.18 - Basic network topology with a perimeter network
Once you’ve designed a redundant topology, you can now segment your network in order to create a multitiered environment. You don’t necessarily have to wait to subnet your environment until after you’ve designed a redundant topology. You can create your subnetted structure before you design redundancy into the topology or as you’re designing the redundant structure. The step is separated here in order to provide a better overview of the design process.
To subnet the network, you should determine how many network segments you’ll use for the part of your network that isn’t exposed to the Internet. Base your decision on the diagram illustrated in the answer to Exercise 1.
The next step in creating your network topology is to design the DNS namespace. The company has already registered the name contoso.com with an Internet name authority. You can choose to use the same name for your external and internal namespaces, or you can use different names.