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Networks are frequently called upon to supply services beyond those originally anticipated. Not that long ago, video and voice over data networks (LAN systems) were costly and lacked sufficient business drivers for implementation. As the technology advances, more and more firms are exploring these services.
In addition, there may be enhancements to existing systems that greatly add to the networks burden. Consider a simple database that contains the names and addresses of a companys customers. Each record might average 2,000 charactersless than 10,000 bits, including overhead. When the database is enhanced to include digital images of the customers and their homes in addition to a transcript of their previous five calls, it is easy to see the potential impact. What was 2,000 characters may exceed 2 million, possibly resulting in millions of bits per transaction. No protocol was added to the network nor were additional users placed in the switch, but the impact would greatly tax even the best designs.
One of the most significant costs in the network results from the move, add, and change (MAC) process. This process refers to the effort involved in installing new users onto the network or changing their installation. The MAC process also includes the relocation of users and their systems.
Various studies have been conducted to measure the true cost of MAC efforts, directly related to both the network costs and the lost productivity of the workers affected. Given that employees may earn $50 an hour on average, a half-day move of even 20 employees will cost $4,000 in lost productivity, not including the impact on non-moved workers. Add the cost of wiring, configuring, installing, and relocating workstations and other systems, and the cost jumps significantly. With the average worker moving 1.1 times per year (according to some surveys from 1997), it is easy to see how this minor cost would quickly impact the finances of the company.
To address these costs, vendors have added features to simplify and accelerate the MAC process. These may include the use of VLAN/ELAN technology (Virtual LANs/Emulated LANs) and DHCP, for example. DHCP is a dynamic method for assigning IP addresses to workstations. The designer should consider these features in any new design and use any cost savings to help offset the initial costs against the recurring costs.
Protocol scalability refers to a protocols ability to service increasingly larger numbers of nodes and users. As an example, IP is capable of servicing millions of users with careful planning and design. AppleTalk, in contrast, does not scale well due to the chatty nature of the protocol and its use of broadcasts and announcements to inform all devices in the network about all other resources. IPX/Novell and NetBIOS share these limitations. Keep in mind that scalable protocols are frequently routablethey contain a Layer 3 address that routers can use for logical grouping. This address further groups and segments systems for efficiency.
If there is one aspect of network design that overshadows all others, it would have to be the integration of the business objective with the implementation.
Consider these scenarios for a moment. A network is designed to carry datadata that is increasingly critical to a business. In addition, this business funds the network equipment and implementation. A similar scenario may involve a small home network. In preparing for a Cisco examination, an administrator creates a small lab with the objective of passing the test. Or the home user wishes to establish a LAN for sharing a printer and some files. On a grander scale, an international corporation uses networks to exchange data with business partners and workgroups alike. In each scenario, each of these groups is choosing to spend money on a network in the hope that the initial costs will be offset by the improvements in productivity or increased sales. Business types refer to this as opportunity cost, and network designers should use this term as well.
There are really two types of business relationships that involve network designers. The first presents itself in the form of the requester. The requester may be the administratorperhaps a technical benefit has been identified with respect to changing routing protocols. It is more likely that the request originates with the business itself, however. Such a request might appear in the form of a need to transfer billing information to a financial clearinghouse or configuring a system to permit salespeople to access their e-mail on the road. Whatever the request, the components of implementation remain fairly consistent. Cost, compatibility, security, supportability, and scalability all enter into the equation, and each of these will impact different business units differently.
There have been many incredible network designs presented to CIOs and presidents of large corporations. Of all these designs, only a handful are actually implemented. Only those network designs that reflect an under-standing of a companys business needs and objectives are worthy of implementationat least from a textbook perspective. For example, consider a simple request for a connection to the Internet. From a technical perspective, a design using OC-48 might be just as valid as a connection using ISDN (Integrated Services Digital Network) or ADSL (Asymmetric Digital Subscriber Line). Yet few would consider placing a 100,000-person company on a single ISDN BRI (Basic Rate Interface) or purchasing a SONET ring for a small school. Designing a network without an understanding of the objective(s) is folly at best.
So, what is a business relationship and how does it fit into the design of a network or the preparation for an examination? Well, the truth is that this is a hard question to prepare for, even though network designers are confronted with this challenge each and every day. This is why such a seemingly simple topic requires so much attention.
A business relationship ideally begins before a project is conceived and involves a bit of cooperation. Many companies place an information specialist in at least one departmental meeting each week to ask questions at the same time the business challenge is addressed. This also affords the opportunity to provide as much warning as possible to the network, server, and workstation groups (assuming that they are different). The relationship may take on an informal tonethere is nothing wrong with obtaining information about the Marketing departments newest effort during the company volleyball game, as an example. The objective remains the same: to provide as much assistance to the business as early in the process as possible.
For the designer who is approaching the task of setting up a network for the first time, it would be nice to have an overview of the tasks that are frequently required. This design methodology is presented as a very high-level overview of the design process. Figure 1.13 provides a general outline of the steps necessary for a successful network design.
FIGURE 1.13 Basic network design methodology
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