The maximum supported unrepeated distance, point-to-point, is 300 meters (984 ft). A client-supplied cable is required. The following types of cables can be used for connecting the port to the selected 10 GbE switch or to the 10GbE RoCE Express feature on the attached server: 

GLYPH<SM590000> OM3 50-micron multimode fiber optic cable that is rated at 2000 MHz-km that ends with an LC Duplex connector (supports 300 meters (984 ft)) 

GLYPH<SM590000> OM2 50-micron multimode fiber optic cable that is rated at 500 MHz-km that ends with an LC Duplex connector (supports 82 meters (269 ft)) 

GLYPH<SM590000> OM1 62.5-micron multimode fiber optic cable that is rated at 200 MHz-km that ends with an LC Duplex connector (supports 33 meters (108 ft)) 

For more information about the management and definition of the 10GbE RoCE, see Appendix D, “Shared Memory Communications” on page 475, and Appendix C, “Native Peripheral Component Interconnect Express” on page 469. 

## Shared Memory Communications functions 

The Shared Memory Communication (SMC) capabilities of the z14 help optimize the communications between applications for server-to-server (SMC-R) or LPAR-to-LPAR (SMC-D) connectivity. 

SMC-R provides application transparent use of the RoCE-Express feature. This feature reduces the network overhead and latency of data transfers, which effectively offers the benefits of optimized network performance across processors. 

SMC-D was used with the introduction of the Internal Shared Memory (ISM) virtual PCI function. ISM is a virtual PCI network adapter that enables direct access to shared virtual memory providing a highly optimized network interconnect for IBM Z intra-CPC communications. 

SMC-D maintains the socket-API transparency aspect of SMC-R so that applications that use TCP/IP communications can benefit immediately without requiring any application software or IP topology changes. SMC-D completes the overall SMC solution, which provides synergy with SMC-R. 

SMC-R and SMC-D use shared memory architectural concepts, which eliminates the TCP/IP processing in the data path, yet preserves TCP/IP Qualities of Service for connection management purposes. 

## Internal Shared Memory 

ISM is a function that is supported by IBM z14™, z13, and z13s machines. It is the firmware that provides connectivity by using shared memory access between multiple operating system images within the same CPC. ISM creates virtual adapters with shared memory that is allocated for each OS image. 

ISM is defined by the FUNCTION statement with a virtual CHPID (VCHID) in hardware configuration definition (HCD)/IOCDS. Identified by the PNETID parameter, each ISM VCHID defines an isolated, internal virtual network for SMC-D communication, without any hardware component required. Virtual adapters are defined by virtual function (VF) statements. Multiple LPARs can access the same virtual network for SMC-D data exchange by associating their VF with same VCHID. 

Applications that use HiperSockets can have network latency and CPU reduction benefits and performance improvement by using the SMC-D over ISM. 

