Issue link: https://www.e-digitaleditions.com/i/1386104
12 I ICT TODAY FIGURE 3: MPO connector options for 400GBASE-SR8. The 16-fiber MPO connector has an offset key. DATA CENTER CONNECTOR TRENDS When data centers were mainly running 1 or 10 Gb/s networks, the LC connector was the simple choice. As 40 Gb/s and 100 Gb/s adoption took off, MPO con- nectors became a popular option. For these networks, the large majority of links for 200 and 400 Gb/s use either duplex LC or parallel MPO connections. The 400 Gb/s transceivers operate over 2, 4, 8 or 16 fibers, depending on the transceiver type. For example, there are three MPO connector choices for delivering 400GBASE-SR8, which uses 8 optical channels (16 total multimode fibers), with each channel operating at 50 Gb/s. These MPO connectors include 24-fiber and 8-fiber options, both ubiquitous, as well as a new 16-fiber variant. The 16-fiber MPO connector "key" is offset (Figure 3), so it will not be accidentally mated with another MPO variant. FIGURE 5: Shows new SN and MDC connector form factors. FIGURE 4: Shows how two CS connectors fit into the same space as a single duplex LC connector. LC Interface CS Interface SFP-DD Interfaces QSFP-DD Interfaces SN-Dual MDC-Dual SN-Quad MDC-Quad In addition to the LC and MPO, there are several new connector options for 400 Gb/s and 800 Gb/s, known as very small form factor (VSFF) connectors. These duplex connectors are used in QSFP-DD and SFP-DD transceivers to increase port density at switch ports over traditional LC duplex connectors. Based on the multi-vendor Quad Small Form-factor Pluggable Double Density (QSFO-DD) MSA Group, three VSFF variants include CS, SN, and MDC connectors. The CS connectors allow for four fibers in the same footprint as a 2-fiber LC connector as shown in Figure 4. The SN and MDC connectors, smaller than the CS connector, have vertically oriented transmit and receive fibers. They allow for 2 duplex connections in an SFP-DD interface and 4 duplex connections in a QSFP-DD inter- face as shown in Figure 5. These new VSFF connectors are relatively new to the market, and it is currently unclear which will gain the largest market acceptance. 8-fiber MPO 16-fiber MPO 24-fiber MPO