How do you read Ethernet standard names like 1000BASE-T, 10GBASE-LR or 100GBASE-SR4?
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The number is the speed in Mbps (or G for gigabits). BASE means baseband signaling. The suffix names the medium and reach: T twisted pair, SX and SR short reach on multimode, LX and LR long reach (about 10 km) on single-mode, ER extended (40 km), CR copper twinax (DAC), KR backplane. A trailing number is the lane count: SR4 uses four lanes, which for SR4 means four fiber pairs.
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Useful IEEE amendments to know
| Amendment | Adds |
|---|---|
| 802.3u | 100BASE-TX Fast Ethernet |
| 802.3z | 1000BASE-SX and LX (fiber gigabit) |
| 802.3ab | 1000BASE-T |
| 802.3ae | 10 Gbps over fiber |
| 802.3an | 10GBASE-T |
| 802.3ba | 40 and 100 Gbps |
| 802.3by | 25 Gbps |
| 802.3bz | 2.5GBASE-T and 5GBASE-T |
| 802.3af, at, bt | PoE, PoE+, 4-pair PoE |
Reading a few
1000BASE-T: 1 Gbps over four pairs of Cat5e or better, 100 m.10GBASE-SR: 10 Gbps, 850 nm, multimode, 300 m on OM3.25GBASE-CR: 25 Gbps over a twinax DAC, a few meters.100GBASE-LR4: 100 Gbps as four 25 Gbps wavelengths on one single-mode pair, 10 km.
They will ask next
What is the difference between SR4 and LR4 in how they use fiber?
SR4 runs four lanes in parallel over eight multimode fibers on an MPO connector. LR4 multiplexes four wavelengths onto one single-mode fiber pair with LC connectors.
Traps
- Guessing ZR is an IEEE standard name for 10G. 10G ZR (about 80 km) is a vendor and MSA term.
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