Enterprise networks are used by businesses to accomplish the everyday functions essential to their success. They are characterized by requirements for features, functionality, and scale that go far beyond typical consumer needs for telecommunications services. Enterprise networks can be very large, spanning the entire globe and operating with multimillion-dollar annual budgets, or they can be much more modest in scale, conforming to the needs of a small business operating in a distinct geographical area.
No matter how large or small, one defining characteristic of an enterprise network is that in almost all cases it is a means to another end. That is, the company that pays for and supports the network is not primarily in the communications business, but rather is in some other business supported by the network. Salespeople make calls to customers and to the home office. Product planners on opposite sides of a continent or an ocean hold weekly conference calls supported by high-quality graphics. A call center takes customer orders or provides support to users of the firm’s products. Remote workers dial in to the company network for e-mail and voice mail. All of these activities are essential to conducting the firm’s business, and some may place critical and demanding requirements on the network, but they are not in themselves the reason why the firm is in business or the sources of its revenue.
The degree to which the network is managed and operated by the firm itself, or to which these functions are outsourced to another company, varies from firm to firm. In the one case, you as the network manager may have a staff of employees that you hire, compensate, and coach in performing tasks to keep the network up and running and expand and extend it to keep pace with user demand. In the other case, you may be primarily responsible for managing the relationship with an outsourcing vendor who in turn performs these tasks. Either way, one of your central concerns is likely to be the costs of network operations, and managing these costs within a budget may be a major function of your job.
Enterprise networks often differ in scale and geographical scope, as mentioned previously. You must consider size and scale when you evaluate your Internet and telecommunications integration needs. Since cost savings is an important goal, it is essential to understand how scale and geographical scope can affect IP telephony costs, including the effects of government regulation in different jurisdictions.
The following sections introduce some possible enterprise network environments. As noted previously, you may find that your own environment is some combination of these, or that it is somewhat different from any of them. Nonetheless, they should provide a framework for thinking about the applicability of Internet and telecommunications integration to your business.
A SOHO environment can be a small office in a business location, a small office located in a private home, or even a home office setup designed primarily to support a remote worker for a large business. There may be several workers in the office with voice and data communication needs, or there may be just one. In either case, needs for communication within the office are likely to be minimal; the most demanding need is for communication outside the office with customers and suppliers, and, in the remote worker case, with other employees and centralized facilities of the large business. Depending on the nature of the business, the scope of communication may be local, regional, national, or international.
To support voice communications, the most readily available traditional options will be based on switched telephone service from the local telephony provider, possibly augmented by relatively simple premises telephone equipment (an electronic key system or the like) to help manage multiple lines. Connections to Internet service providers (ISPs) or the internal network of a large business can also most readily be supported on a dial-up basis. Depending on the locality, you may have other options such as cable modems or digital subscriber line (DSL) technology.
The medium to large business with a single building or campus category can span locations with less than a dozen to more than 1000 employees. A defining characteristic is a significant need to provide communication among the colocated employees (for example, at an R&D site or large professional office) and/or to manage high-volume incoming or outgoing communications (as at a call center).
Traditionally, voice communications for a single campus location would be handled by a digital private branch exchange (PBX) supported by a substantial in-building twisted pair wiring infrastructure. In a minority of cases (usually governmental organizations or other institutions with a limited ability to raise capital for buying things like PBXs), the same functions may be provided by Centrex service from a telephone company. For call center operations, a special feature of PBX called automatic call distribution (ACD) may be in use, possibly along with computer telephony (CT) capabilities to optimize the flow of calls and connect agents with customer information databases and other information systems. Data communications would be provided by local area network (LAN) technology, probably running over the same twisted pair infrastructure as the telephone system, using networking technology like switches and routers. Depending on the scale of the operation, you may have a hierarchy of departmental and backbone LANs.
Communications outside the building or campus may use a combination of local, regional, national, and international services, depending on the nature of the business. If the building or campus is part of a larger business, a substantial amount of off-premises voice and data traffic may flow over private facilities such as leased circuits or specialized carrier services like software defined networks (primarily for voice) or frame relay service (traditionally for data). Switched business lines from the local telephony provider are available as the ultimate default.
The medium to large business with more than one campus is a generalization of the preceding category. All of the same characteristics are present. The new factor is that there are substantial traffic flows between two or more buildings/campuses. As a result, there will often be significant use of private facilities or specialized carrier services to connect the multiple large locations. Distances between pairs of buildings/campuses, of course, can vary enormously, from a few miles/kilometers to intercontinental distances, and may have a great impact on the specific services available for interconnection as well as on the relative economics of different options.
Many medium to large organizations fall in the category of medium to large businesses with single or multiple campuses with small remote locations. Not only are there possibly multiple large buildings or campuses with substantial traffic flows among them, but there are very important communication flows to and from a relatively large number of small locations. These small locations may be similar in character to the small office/home office environments described previously, or they may be a bit larger, more like the lower end of the single-campus category. All of the communication options described in the preceding two categories may be in place, and in addition the small remote offices present important communication requirements that may need to be satisfied by a combination of switched business lines, specialized carrier services, and, if traffic densities are high enough and the economics work out, leased lines like T1s or cable-based circuits.
The limiting case of the small remote office is probably the single nomadic worker who needs to stay in touch with the business through whatever combination of e-mail, voice mail, and fax he or she can manage. Communications options for this increasingly important case are typically based on dial-up from wired or wireless telephones into corporate voice networks and/or remote access servers for corporate data networks.
All of the preceding categories include some amount of communication between the enterprise in question and other businesses, including suppliers, distributors, and business customers. The default communication mechanism for such communication flows is the public telephone network, whether employed for voice or fax transmission, or maybe the post office, or, in a small but growing number of instances, the public Internet. However, for high-volume transactions between companies that are regular, long-term partners, intercompany private networks or industry-wide jointly managed networks are sometimes employed. Examples are the use of electronic data interchange (EDI) for functions like ordering and invoicing, and electronic funds transfers in the banking industry. Internet technology is often adapted to interenterprise uses in the form of an extranet—an IP-based network that is neither public nor strictly private and that is used by two or more businesses with a long-term relationship.
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