## RoCE Express 

The 25GbE and 10GbE RoCE Express2.1 features use Remote Direct Memory Access (RDMA) over Converged Ethernet (RoCE) to provide fast memory-to-memory communications between two Z platforms. 

These features are designed to help reduce consumption of CPU resources for applications that use the TCP/IP stack (such as IBM WebSpherefi that accesses an IBM Db2 database). They can also help reduce network latency with memory-to-memory transfers by using Shared Memory Communications over RDMA (SMC-R). 

With SMC-R, you can transfer huge amounts of data quickly and at low latency. SMC-R is transparent to the application and requires no code changes, which enables rapid time to value. 

## Internal Shared Memory 

Internal Shared Memory (ISM) is a virtual PCI network adapter that enables direct access to shared virtual memory, providing a highly optimized network interconnect for Z platform intra-communications. Shared Memory Communications-Direct Memory Access (SMC-D) uses ISM. SMC-D optimizes operating systems communications in a way that is transparent to socket applications. It also reduces the CPU cost of TCP/IP processing in the data path, which enables highly efficient and application-transparent communications. 

SMC-D requires no extra physical resources (such as RoCE Express features, PCIe bandwidth, ports, I/O slots, network resources, or Ethernet switches). Instead, SMC-D uses LPAR-to-LPAR communication through HiperSockets or an OSA-Express feature for establishing the initial connection. 

z/OS and Linux on IBM Z support SMC-R and SMC-D. Now, data can be shared by way of memory-to-memory transfer between z/OS and Linux on Z. 

For more information about the available network connectivity features, see 3.3, “Network connectivity” on page 38. 

## 1.2.4 Cryptography 

z15 provides two major groups of cryptographic functions: CPACF and Crypto-Express7S. 

## CPACF 

CPACF is a high performance, low latency co-processor that performs symmetric key encryption and calculates message digests (hashes) in hardware. The following algorithms are supported: 

GLYPH<SM590000> AES 

GLYPH<SM590000> DES/TDES 

GLYPH<SM590000> SHA-1 

GLYPH<SM590000> SHA-2 

GLYPH<SM590000> SHA-3 

With z15, CPACF supports Elliptic Curve Cryptography clear key, improving the performance of Elliptic Curve algorithms. The following algorithms are supported: 

GLYPH<SM590000> EdDSA (Ed448, Ed25519) 

GLYPH<SM590000> ECDSA (P-256, P-384, P-521) 

GLYPH<SM590000> ECDH (P-256, P-384, P521, X25519, X448) 

GLYPH<SM590000> Support for protected key signature creation. 

