| ==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 | |
| ------------------------------------------------------------------------------ | |
| 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. | |