Business Data Networks And Security 9th Edition Pdf Download __TOP__
SBC is a corporation organized and existing under the laws of the State of Delaware, with its headquarters in San Antonio, Texas. SBC, formerly Southwestern Bell, is a regional bell operating company ("RBOC"), formed as one of the seven regional holding companies created as a result of the breakup of AT&T's telephone business into local and long distance components initially in 1984. Since then, SBC has acquired two other RBOCs--Pacific Telesis and Ameritech--as well as an incumbent local exchange carrier ("ILEC"), Southern New England Telephone Corporation. SBC owns and operates local telecommunications networks throughout its 13-state territory and provides local and long distance voice and data services to, inter alia, business customers and other telecommunications carriers. SBC's wireline telecommunications operations currently serve around 52 million switched access lines, including 27.5 million residential and 17.6 million business lines. In 2004, SBC earned approximately $36.9 billion in revenues from its wireline services, including almost $13 billion attributable to business customers.
business data networks and security 9th edition pdf download
AT&T is a corporation organized and existing under the laws of the State of New York, with its headquarters in Bedminster, New Jersey. After the 1984 breakup, AT&T was primarily a long distance provider and is still the nation's largest interexchange carrier ("IXC"), offering traditional long distance telephone service, as well as one of the largest competitive local exchange carriers ("CLEC"), offering local network access for voice and data services. AT&T serves consumers and businesses across the United States and around the globe. It also owns and operates local networks in dozens of metropolitan areas in the United States, a substantial number of which are in SBC territory. Like SBC, AT&T also provides local and long distance voice and data services to business customers and other telecommunications carriers. AT&T competes with SBC to serve wholesale and retail customers' locations in SBC's franchised territory. In 2004, AT&T earned approximately $30.5 billion in revenues, including $22.6 billion from business customers.
Local Private Lines are a recognized service category among telecommunications carriers and end-user business customers and are sold at both retail (to business customers) and wholesale (to other carriers). Depending on how they are configured, Local Private Lines can be used to carry voice traffic, data, or a combination of the two. Local Private Lines may be purchased as stand-alone products but are also an important input to value-added voice and data telecommunications services for business customers and represent a significant portion of the costs incurred in providing those services. Customers typically purchase Local Private Lines in standard bandwidth increments such as DS1 ("T1," 1.54 megabits per second), DS3 (44.74 megabits per second), OC3 (155.52 megabits per second), and higher. Local Private Lines can interconnect with industry-standard data networking and telephone equipment, and can be "channelized" to carry various amounts of voice and/or data traffic. Local Private Lines are distinct from switched local exchange telephone services, which route calls through a voice switch in the local carrier's central office and do not necessarily use a dedicated circuit. Customers do not consider switched local exchange services to be a substitute because they do not offer the guaranteed bandwidth, high service levels, and security that Local Private Lines provide.
Competing carriers often rely on Local Private Line circuits to connect an end-user customer's location to their networks, enabling the competitor to supply value-added data networking, Internet access, local voice and long distance services to the customer. Although carriers can provide some types of voice and data services over switched local exchange lines (e.g., when an access line is pre-subscribed to a long distance carrier), most large business customers do not find those services to be a viable or cost-effective substitute for voice and data telecommunications services provided via Local Private Lines. In the event of a small, but significant, nontransitory increase in price for either Local Private Lines or voice and data telecommunications services provided via Local Private Lines, insufficient customers would switch to switched circuits to render the increase unprofitable.
For the vast majority of commercial buildings in its territory, SBC is the only carrier that owns a last-mile connection to the building. Thus, in order to provide Local Private Line circuits or voice or data telecommunications services to customers in those SBC-only buildings, competing carriers typically must lease the connection from SBC as Local Private Line service, which SBC refers to as "special access." For a small percentage of commercial buildings (though these buildings account for a significant amount of customer demand and revenue), SBC's CLEC competitors have built or acquired their own last-mile fiber-optic connections, separate from SBC's, to connect their networks to the buildings. The CLECs typically refer to buildings with these connections as their "lit buildings" or "on-net buildings." Once a CLEC has incurred the high fixed cost to construct a last-mile connection to a building, the CLEC can usually provide service to business customers in the building at a lower marginal cost than it would otherwise be able to do if it had to lease the connection from the RBOC. It can also provide alternative access to other CLECs seeking to serve business customers in the building.
As COVID-19 has spread throughout the world and within the United States, companies of all sizes have had to make quick decisions about how to implement work-from-home procedures. While many businesses are accustomed to having some of their employees work remotely at any given time, the sudden shift to a majority of the work force being away from controlled office networks and environments presents a unique and heightened set of technical and cybersecurity challenges.