Digital Subscriber Line (DSL) Variants

 
DSL VariantDescriptionAdvantagesDisadvantages
ADSL - Asymmetrical DSLDelivers high-speed data and POTS voice service over twisted-pair copper wiring.Widely deployed and available with CAP modulation, with downstream speeds up to 7Mbps.Upstream speed limitations are typically 800Kbps with no rate adaption.
UADSL (G.lite) - Universal Asymmetrical DSLA splitterless vairaint of ADSL intended primarily for the home-consumer mass market.The first end-to-end standard for DSL that will offer full vendor interoperability.Not yet available with speed limitations (max. 1.5Mbps/384Kbps asymmetric, 384Kbps symmetric).
HDSL-High-Bit Rate DSLAn alternative for T1 and E1 using two twisted-pair copper wires.Supports symmetric speeds up to T1 and E1 rates and does not require repeaters between subscriber and CO.No POTS support and requires two wires with no rate adaption. A limited downstream spped (E1 max.).
SDSL - Symmetrical DSLAn alternative scheme for T1 and E1 using one twisted-pair copper wire.Supports symmetric speeds up to T1 and E1 rates and does not require repeaters between subscriber and CO.No POTS support with no rate adaption and a limited downstream speed (E1 max.).
MSDL - Multirate Symmetrical DSLAn alternative scheme for T1 and E1 using one twisted-pair copper wire.Same as HDSL but offers rate adaption and relaxed distance requirements at lower speeds (21,000 feet at 768Kbps).No POTS support.
RADSL- Rate Adaptive DSLDSL vairant tht offers automatic rate adaption.Line speeds can be easily changed to optimize connection or at customer request with a high downstream speed up to 7Mbps. Slow symmetric speeds less than the upstream speed compared to DSLs listed above.
IDSL - ISDN DSLDSL service using ISDN hardware.Moves ISDN users off the switched network and allows DSL service where only ISDN is available.Max. data rate of 144Kbps.
VDSL - Very High Bit Rate DSLUltra high-speed DSL.Speeds of up to 52Mbps possible (34Mbps symmetric).Not yet available and will likely have 1,000 feet to 4,500 feet distance limitation, depending upon the speed.

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Extracted from Network Computing, dated 09/01/98, page 104.

Date of Last Revision: 17 December 2001.