

                                ==Phrack Inc.==
                     Volume One, Issue Two, Phile 6 of 9

                Toward Universal Information Services Via ISDN
                ~~~~~~ ~~~~~~~~~ ~~~~~~~~~~~ ~~~~~~~~ ~~~ ~~~~
                                 by Taran King

                From PROTO newsletter of AT&T Bell Laboratories
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         Phase one, the Present.
         ~~~~~ ~~~~ ~~~ ~~~~~~~~
         The local network of today, although still largely
         voice-oriented, is already on the path to Universal
         Information Services.  Lightguide fiber is dramatically
         expanding the capacity of local networks, helping to lower
         the costs and increase the demand for high-band width,
         Information Age services.  And public networks are
         increasingly digital and geared for data and special
         services.  For example:

         o The AT&T Network Systems 5ESS (TM <riiiight>) switch,
         designed by Bell Laboratories, can serve as the hub of a
         local deployment of remote modules at locations up to 100
         miles from a host central office.

         o The Integrated Special Services Network (ISSN) is a channel
         network that provides special services, customer control
         options and digital private lines rearrangeable under
         software control.  The ISSN incorporates digital carrier
         terminating equipment such as the D4 Channel Bank, D5 Digital
         Terminal System and Digital Access and Cross-connect System
         (DACS).

         o The New Centrex is bringing greater levels of customer
         control, improved services and a broad range of data
         capabilities to the business customer.

                 Today's public networks consist of multiple or
         overlay networks.  The public switched network, or circuit
         network, mainly for voice, is the base network.  Two kinds of
         overlay networks provide special services.  Channel networks
         carry private lines leased by large customers and transmit
         much of today's data and image traffic; they also handle
         traffic for network operations support.  Packet networks
         carry data communications, while packet switching is used
         internally to public networks for common channel signaling to
         set up, route and take down calls, or to give customers
         information.
                 "Overlay networks help telecommunications companies
         efficiently meet growing demand for digital transmission and
         special services," says Stan Johnston, Market Planning
         Manager, Network Systems Evolution, in AT&T Network Systems.
         "Their integration into a single network, however, would be
         still more effective."

         Phase two, the Integrated Services Digital Network (ISDN).
         ~~~~~ ~~~~ ~~~ ~~~~~~~~~~ ~~~~~~~~ ~~~~~~~ ~~~~~~~ ~~~~~~~
         The ISDN is a concept to which AT&T is committed - and it's
         the foundation for Universal Information Services.  The
         central idea of ISDN, as AT&T Network Systems sees it, is to
         provide an individual user a link to the local central office
         of generous band-width - a digital subscriber line that can
         carry 144,000 bits per second (sure beats 2400 baud!).  The
         band-width is subdivided into two 64,000-bit channels, which
         may carry voice or data or both, and one 16,000-bit channel
         for packetized signaling information or data transport.  Such
         a link provides convenient "integrated" network access by
         accommodating voice, data and signaling over a single line.
                 The ISDN will make it easier for a customer to get
         varied services from public and private networks.  More
         bandwidth for big customers will be available through another
         ISDN access standard, the extended digital subscriber line,
         which provides 1.5 billion bits per second as 24 channels of
         64,000 bits each.
                 In 1986, new software from Bell Labs will enable the
         5ESS switch to accommodate ISDN-sized 144,000-bit channels
         that standardize and simplify subscribers' use of local
         networks.  AT&T is committed to future products that will
         also be ISDN-compatible.  Other vendors, too, some of whom
         already plan to build premises, terminal, and other
         equipment to ISDN standards, will make ISDN a cooperative
         effort.
                 By providing integrated digital access to networks,
         ISDN will make important progress toward the goal of
         Universal Information Services.  But overlay networks will
         continue to divvy up the transport job.  And messages needing
         less than 144,000 bits per second will not fill their
         allotted bandwidth, leaving capacity underutilized.

         Phase three, Universal Information Services.
         ~~~~~ ~~~~~~ ~~~~~~~~~ ~~~~~~~~~~~ ~~~~~~~~~
         Rooted in the fertile ground of 5ESS switches, ISDN equipment
         and technologies such as wideband packet transport, Universal
         Information Services will bear fruit during the 1990s.  From
         a single kind of network will hang services as different as
         apples, oranges and pears.  Just as network access was
         integrated in ISDN, transport functions will increasingly be
         integrated by powerful new network equipment evolved from
         equipment developed for the ISDN.  Where customers once got
         standard-sized ISDN channels, they'll get big bandwidth for
         large jobs, little bandwitdh for small jobs.
