Link and Channel Classes
The standard defines several classes of twisted-pair copper interconnects, which differ in the maximum frequency for which a certain channel performance is required:
- Class A: up to 100 kHz using elements category 1
- Class B: up to 1 MHz using elements category 2
- Class C: up to 16 MHz using elements category 3
- Class D: up to 100 MHz using elements category 5e
- Class E: up to 250 MHz using elements category 6
- Class EA: up to 500 MHz using elements category 6A (Amendment 1 and 2 to ISO/IEC 11801, 2nd Ed.)
- Class F: up to 600 MHz using elements category 7
- Class FA: up to 1000 MHz using elements category 7A (Amendment 1 and 2 to ISO/IEC 11801, 2nd Ed.)
The standard link impedance is 100 Ω. (The older 1995 version of the standard also permitted 120 Ω and 150 Ω in classes A−C, but this was removed from the 2002 edition.)
The standard defines several classes of optical fiber interconnect:
- OM1: Multimode fiber type 62.5 µm core; minimum modal bandwidth of 200 MHz*km at 850 nm
- OM2: Multimode fiber type 50 µm core; minimum modal bandwidth of 500 MHz*km at 850 nm
- OM3: Multimode fiber type 50 µm core; minimum modal bandwidth of 2000 MHz*km at 850 nm
- OM4: Multimode fiber type 50 µm core; minimum modal bandwidth of 4700 MHz*km at 850 nm
- OS1: Singlemode fiber type 1db/km attenuation
Read more about this topic: ISO/IEC 11801
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—Henry David Thoreau (1817–1862)