Additional Cable Latency

In addition to speed of light delay—roughly 5 nanoseconds per meter depending on the cable technology—copper Ethernet links may require Forward Error Correction (FEC) to achieve the necessary BER.

FEC techniques introduce additional link delays of up to 120 nanoseconds because they add redundant error correcting codes to every data frame. In latency sensitive applications, use of low-loss DAC cables can eliminate the need for FEC. Such cables implement the IEEE CA-N or CA-L standards.

SFP Connectors

In addition to the QSFP connectors that are common between Ethernet and InfiniBand, Ethernet uses small form-factor pluggable (SFP) connectors for 10 GbE (SFP+), 25 GbE (SFP28), and 50 GbE (SFP56) cables. SFP connectors (Figure 26) are used for cables and for transceivers.

Figure 26. SFP connector

1G BASE-T Connectivity

Connections to 1G BASE-T cables can be achieved using an adapter that has an SFP+ connector on the port side and an RJ45 jack on the cable side (Figure 27).

Figure 27. SFP to 1G BASE-T (RJ45) adapter