The international digital heirarchy

• DS0 DS-1 DS-3

• channels channels channels

• DS-0 1 64 kb/s

• DS-1 24 1 1.544 mb/s

• E-1 30 1.25 2.048 mb/s

• DS-1C 48 2 3.152 mb/s

• DS-2 96 4 6.132 mb/s

• E-2 120 5 8.448 mb/s

• E-3 480 20 34.368 mb/s

• DS-3 672 28 1 44.736 mb/s

• OC-1 672 28 1 51.84 mb/s

• OC-3 2,016 84 3 155.52 mb/s

• OC-12 8,064 336 12 622.08 mb/s

• OC-24 16,128 672 24 1.24 gb/s

• OC-48 32,256 1344 48 2.49 gb/s

• OC-192 129,024 5376 192 9.95 gb/s

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This chart is one way of keeping track of how fast is fast when twlking about data speeds. The basic unit of digital speed, the “meter” as it were, is the DS-0 at 64 thousand bits per second. It is a convenient number in digital arithmetic and is sufficient to carry the human voice in digital form with adequate quality.

DS-1 and E-1 speeds are widely available for use by high volume users such as internet service providers. The speeds from OC-3 (which stands for Optical Carrier level 3) on up are now used for backbone, behind-the-scenes networking, but we can expect them to become more commonly available for end-users in the next couple of years.