The following types of FICON Express16S optical transceivers are supported: GLYPH<SM590000> FICON Express16S LX feature, FC 0418, with two ports per feature, supporting LC Duplex  connectors GLYPH<SM590000> FICON Express16S SX feature, FC 0419, with two ports per feature, supporting LC  Duplex connectors For more information about supported distances, see Table 4-6 on page 172. Consideration:  FICON Express16S features do not support auto-negotiation to a data link  rate of 2 Gbps (only 4, 8, or 16 Gbps). FICON Express8S The FICON Express8S feature is installed in the PCIe I/O drawer. Each of the two  independent ports is capable of 2 Gbps, 4 Gbps, or 8 Gbps. The link speed depends on the  capability of the attached switch or device. The link speed is auto-negotiated, point-to-point,  and is transparent to users and applications.  The following types of FICON Express8S optical transceivers are supported: GLYPH<SM590000> FICON Express8S LX feature, FC 0409, with two ports per feature, supporting LC Duplex  connectors GLYPH<SM590000> FICON Express8S SX feature, FC 0410, with two ports per feature, supporting LC Duplex  connectors For more information about supported distances, see Table 4-6 on page 172. FICON enhancements Together with the FICON Express16SA and FICON Express16S+, z15 servers provide  enhancements for FICON in functional and performance aspects with IBM Endpoint Security  solution. Forward Error Correction Forward Error Correction (FEC) is a technique that is used for reducing data errors when  transmitting over unreliable or noisy communication channels (improving signal to noise  ratio). By adding redundancy error-correction code (ECC) to the transmitted information, the  receiver can detect and correct several errors without requiring retransmission. This process  feature improves signal reliability and bandwidth use by reducing retransmissions because of  bit errors, especially for connections across long distance, such as an inter-switch link (ISL) in  a GDPS Metro Mirror environment.  The FICON Express16SA, FICON Express16S+, and FICON Express16S are designed to  support FEC coding on top of its 64b/66b data encoding for 16 Gbps connections. This  design can correct up to 11 bit errors per 2112 bits transmitted. Therefore, while connected to  devices that support FEC at 16 Gbps connections, the FEC design allows FICON  Express16SA, FICON Express16S+, and FICON Express16S channels to operate at higher  speeds over longer distances with reduced power and higher throughput while retaining the  same reliability and robustness for which FICON channels are traditionally known. With the IBM DS8870 or newer, z15 servers can extend the use of FEC to the fabric N_Ports  for a completed end-to-end coverage of 16 Gbps FC links. For more information, see the  IBM  DS8884 and z13s: A new cost optimized solution , REDP-5327.  176  IBM z15 (8561) Technical Guide