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ADSL Interface Overview

Asymmetric digital subscriber line (ADSL) technology is part of the xDSL family of modem technologies that use existing twisted-pair telephone lines to transport high-bandwidth data. ADSL lines connect service provider networks and customer sites over the "last mile" of the network—the loop between the service provider and the customer site.

ADSL transmission is asymmetric because the downstream bandwidth is typically greater than the upstream bandwidth. A typical ADSL circuit uses bandwidths of 1.5 Mbps to 2.0 Mbps downstream and 16 Kbps upstream. Depending on the length of the copper wire, an ADSL link can have up to 6.1 Mbps downstream and 64 Kbps upstream.

All J-series Services Routers support ADSL, ADSL2, and ADSL2+, which comply with the following standards:

For Annex A and B—ITU G.992.1 (ADSL)
For Annex A only—ANSI T1.413 Issue II, ITU G.992.3 (ADSL2) and ITU G.992.5 (ADSL2+)
For Annex B only—ETSI TS 101 388 V1.3

Note: J-series devices with ADSL PIMs can use PPP over Ethernet (PPPoE) and PPP over ATM (PPPoA) to connect through ADSL lines only, not for direct ATM connections.

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