Short Reach (SR) Transceivers
For distances <200m, transceivers using multi-mode fiber are cost-effective. There are two categories:
SR: these transceivers have an SFP connector on one end and a duplex LC connector for the optical cable. Typical reach is 100m for 25 GbE and 50 GbE.
SR4: these transceivers have a QSFP connector on one end and an MPO-12 receptacle for the optical cable. Typical reach is 150m for 40 GbE, and 100m for 100 GbE and 200 GbE. MPO-12 cables are discussed in InfiniBand Cables Primer.
See Figure 30 for examples of short reach transceivers.
Figure 30. QSFP to SFP (QSA) adapters
Long Reach (LR) Transceivers
Transceivers for longer distances use single-mode fiber. Multilane signaling is accomplished using Wavelength division multiplexing (WDM) over a single fiber. Table 5 shows several types that available for different speeds and distances.
Table 5. LR transceiver specifications
Type |
Speed |
Maximum Distance |
|---|---|---|
PSM4 |
100 GbE |
500m using eight optical fibers in an MPO-12 cable |
CWDM4 |
100 GbE |
2 km using a pair of single-mode fibers with duplex LC connectors at each end |
LR |
25 GbE |
10 km using two single-mode fibers with duplex LC connectors at each end |
LR4 |
100 GbE |
10 km over a pair of single-mode fibers with duplex LC connectors at each end |
ER |
100 GbE |
40 km using two single mode fibers with duplex LC connectors at each end |
Examples of LR transceivers are shown in Figure 31.
Figure 31. Ethernet LR transceivers
