AT&T 7100 series Public and Private Data Network Connections, Public Data Networks, APS Access

PUBLIC AND PRIVATE DATA NETWORK CONNECTIONS

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This section describes how to use public and private digital data networks to link DTEs and local area networks spread across a wide geographical area. These data networks ensure end to end digital transmission and can be packet-switched or circuit-switched.

PUBLIC DATA NETWORKS

Public data networks provide on-demand access to shared digital facilities. Public data networks can be either packet-switched or circuit-switched.

Packet-Switched Public Data Networks

Packet-switched data networks use packet switches and high-speed links to transport blocks of data — consisting of header, trailer, and text information — as integral units from their origin to their destination.

For public network packet switching, AT&T offers the ACCUNET Packet Service (APS). APS can transmit packets of data throughout the United States. The packets must be formatted according to X.25 protocol, and connections with other packet switches, including international APS, are governed by X.75 protocol.

ACCUNET Packet Service

ACCUNET Packet Service (APS) delivers X.25 packetized data throughout the U.S. at digital speeds of 2.4 through 56 kbps and analog speeds of 2.4, 4.8, and 9.6 kbps.

APS Applications

APS is ideal for applications where information is transmitted in short bursts and at random intervals. This may include:

∙Database searches and updates

∙Electronic messaging

∙Electronic order exchange

∙File transfers

APS Access

For data that has already been formatted according to X.25, access to APS may be through DDS, an analog private line, or even a digital DS1 channel. For data that has not yet been packetized, however, two other access arrangements are possible:

∙Memotec PAD — The Memotec SP/630 PAD is a packet assembler/disassembler (PAD) that interfaces with your communication system to provide X.25 packetization of data for access to the APS. The PAD connects to a digital port on the System 75 and Generic 1 communications system, and to an EIA port on the System 85 and Generic 2 communications system. One SP/630 PAD can connect up to 4

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