Knowledge base

The standard defines several link/channel classes and cabling categories of twisted-pair copper interconnects, which differ in the maximum frequency for which a certain channel performance is required:

Class A: link/channel up to 100 kHz using Category 1 cable/connectors

Class B: link/channel up to 1 MHz using Category 2 cable/connectors

Class C: link/channel up to 16 MHz using Category 3 cable/connectors

Class D: link/channel up to 100 MHz using Category 5e cable/connectors

Class E: link/channel up to 250 MHz using Category 6 cable/connectors

Class EA: link/channel up to 500 MHz using Category 6A cable/connectors (Amendment 1 and 2 to ISO/IEC 11801, 2nd Ed.)

Class F: link/channel up to 600 MHz using Category 7 cable/connectors

Class FA: link/channel up to 1000 MHz using Category 7A cable/connectors (Amendment 1 and 2 to ISO/IEC 11801, 2nd Ed.)

Class BCT-B: link/channel up to 1000 MHz using with coaxial cabling for BCT applications. (ISO/IEC 11801-1, Edition 1.0 2017-11)

Class I: link/channel up to 2000 MHz using Category 8.1 cable/connectors (ISO/IEC 11801-1, Edition 1.0 2017-11)

Class II: link/channel up to 2000 MHz using Category 8.2 cable/connectors (ISO/IEC 11801-1, Edition 1.0 2017-11)

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

OM5: Multimode fiber type 50 μm core; minimum modal bandwidth of 4700 MHz·km at 850 nm and 2470 MHz·km at 953 nm

OS1: Single-mode fiber type 1 dB/km attenuation at 1310 and 1550 nm

OS1a: Single-mode fiber type 1 dB/km attenuation at 1310, 1383, and 1550 nm

OS2: Single-mode fiber type 0.4 dB/km attenuation at 1310, 1383, and 1550 nm