105 lines
5.7 KiB
Plaintext
105 lines
5.7 KiB
Plaintext
==Phrack Inc.==
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Volume One, Issue Two, Phile 6 of 9
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Toward Universal Information Services Via ISDN
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~~~~~~ ~~~~~~~~~ ~~~~~~~~~~~ ~~~~~~~~ ~~~ ~~~~
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by Taran King
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From PROTO newsletter of AT&T Bell Laboratories
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------------------------------------------------------------------------------
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Phase one, the Present.
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~~~~~ ~~~~ ~~~ ~~~~~~~~
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The local network of today, although still largely
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voice-oriented, is already on the path to Universal
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Information Services. Lightguide fiber is dramatically
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expanding the capacity of local networks, helping to lower
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the costs and increase the demand for high-band width,
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Information Age services. And public networks are
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increasingly digital and geared for data and special
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services. For example:
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o The AT&T Network Systems 5ESS (TM <riiiight>) switch,
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designed by Bell Laboratories, can serve as the hub of a
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local deployment of remote modules at locations up to 100
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miles from a host central office.
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o The Integrated Special Services Network (ISSN) is a channel
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network that provides special services, customer control
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options and digital private lines rearrangeable under
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software control. The ISSN incorporates digital carrier
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terminating equipment such as the D4 Channel Bank, D5 Digital
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Terminal System and Digital Access and Cross-connect System
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(DACS).
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o The New Centrex is bringing greater levels of customer
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control, improved services and a broad range of data
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capabilities to the business customer.
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Today's public networks consist of multiple or
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overlay networks. The public switched network, or circuit
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network, mainly for voice, is the base network. Two kinds of
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overlay networks provide special services. Channel networks
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carry private lines leased by large customers and transmit
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much of today's data and image traffic; they also handle
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traffic for network operations support. Packet networks
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carry data communications, while packet switching is used
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internally to public networks for common channel signaling to
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set up, route and take down calls, or to give customers
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information.
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"Overlay networks help telecommunications companies
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efficiently meet growing demand for digital transmission and
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special services," says Stan Johnston, Market Planning
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Manager, Network Systems Evolution, in AT&T Network Systems.
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"Their integration into a single network, however, would be
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still more effective."
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Phase two, the Integrated Services Digital Network (ISDN).
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~~~~~ ~~~~ ~~~ ~~~~~~~~~~ ~~~~~~~~ ~~~~~~~ ~~~~~~~ ~~~~~~~
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The ISDN is a concept to which AT&T is committed - and it's
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the foundation for Universal Information Services. The
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central idea of ISDN, as AT&T Network Systems sees it, is to
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provide an individual user a link to the local central office
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of generous band-width - a digital subscriber line that can
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carry 144,000 bits per second (sure beats 2400 baud!). The
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band-width is subdivided into two 64,000-bit channels, which
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may carry voice or data or both, and one 16,000-bit channel
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for packetized signaling information or data transport. Such
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a link provides convenient "integrated" network access by
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accommodating voice, data and signaling over a single line.
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The ISDN will make it easier for a customer to get
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varied services from public and private networks. More
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bandwidth for big customers will be available through another
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ISDN access standard, the extended digital subscriber line,
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which provides 1.5 billion bits per second as 24 channels of
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64,000 bits each.
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In 1986, new software from Bell Labs will enable the
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5ESS switch to accommodate ISDN-sized 144,000-bit channels
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that standardize and simplify subscribers' use of local
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networks. AT&T is committed to future products that will
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also be ISDN-compatible. Other vendors, too, some of whom
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already plan to build premises, terminal, and other
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equipment to ISDN standards, will make ISDN a cooperative
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effort.
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By providing integrated digital access to networks,
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ISDN will make important progress toward the goal of
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Universal Information Services. But overlay networks will
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continue to divvy up the transport job. And messages needing
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less than 144,000 bits per second will not fill their
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allotted bandwidth, leaving capacity underutilized.
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Phase three, Universal Information Services.
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~~~~~ ~~~~~~ ~~~~~~~~~ ~~~~~~~~~~~ ~~~~~~~~~
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Rooted in the fertile ground of 5ESS switches, ISDN equipment
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and technologies such as wideband packet transport, Universal
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Information Services will bear fruit during the 1990s. From
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a single kind of network will hang services as different as
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apples, oranges and pears. Just as network access was
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integrated in ISDN, transport functions will increasingly be
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integrated by powerful new network equipment evolved from
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equipment developed for the ISDN. Where customers once got
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standard-sized ISDN channels, they'll get big bandwidth for
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large jobs, little bandwitdh for small jobs.
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