The following terms and concepts apply to Shared Memory Communications over Remote Direct Memory Access (SMC-R). You can use this list as needed for brief descriptions when you are using other SMC-R information.
- Associated RNIC interface
- An IBM® 10GbE RoCE Express® interface that is associated with an SMC-R capable interface that has the same physical network ID.
- IBM 10GbE RoCE Express feature
- A feature that enables Remote Direct Memory Access by managing low-level functions that the TCP/IP stack typically handles.
- IBM 10GbE RoCE Express interface
- An interface that is dynamically created by TCP/IP that uses a particular port of an IBM 10GbE RoCE Express feature.
- Internal path
- The System z® internal PCIe infrastructure for IBM 10GbE RoCE Express features. The internal path of a 10GbE RoCE Express feature is determined based on how the feature is plugged into the System z I/O drawers.
Operating system images 
- Logical partitions (LPARs) or guest virtual machines that operate
in the same central processor complex (CPC).
- Physical channel ID (PCHID)
- A 2-byte hexadecimal value that is used to uniquely define a RoCE Express feature.
- PCIe function ID (PFID)
- A value that is configured on the SMCR parameter of the GLOBALCONFIG
statement in the TCP/IP profile to identify an IBM 10GbE RoCE Express feature. The PFID represents a physical RoCE Express feature and must match
a FID value configured in the hardware configuration definition (HCD)
for the PCHID value that identifies the feature. When the RoCE Express feature is installed
on a System z that supports
a shared RoCE environment, the same physical feature can be shared
with other operating system images, and multiple PFID values specified
on the same GLOBALCONFIG statement can represent different ports on
the same physical RoCE Express feature.
- Peripheral Component Interconnect Express (PCI Express, or PCIe)
- A local bus that provides the high-speed data path between the processor and an attached IBM 10GbE RoCE Express feature.
- Physical network ID (PNet ID)
- A value that is defined to uniquely identify your physical layer 2 LAN fabric or physical broadcast domain. You can use this value to logically associate the System z features, adapters, and ports to be physically connected to your network. You specify the PNet ID in a single step within the hardware configuration definition (HCD), and all operating systems of all associated central processor complexes (CPCs) can dynamically learn and use this definition.
- RDMA network interface card (RNIC)
- An IBM 10GbE RoCE Express feature that enables Remote Direct Memory Access by managing low-level functions that are typically handled by the TCP/IP stack.
- RDMA over Converged Ethernet (RoCE)
- An InfiniBand Trade Association (IBTA) standard that enables Remote Direct Memory Access over Converged Ethernet.
- Redundancy level
- For an SMC-R link group, this value indicates the level to which z/OS® Communications Server can provide dynamic failover processing if there is a failure of an underlying IBM 10GbE RoCE Express interface or the associated network hardware.
- Reliable connected queue pair (RC QP)
- A logical connection between two virtual servers that enables that specific pair of servers to use RDMA communications between themselves.
- Remote Direct Memory Access (RDMA)
- A high-speed, low-latency network communications protocol in which data is transferred directly to the memory of a remote host with no involvement from the remote host processors or operating system.
- Remote memory buffer (RMB)
- Local memory that is used to receive inbound data over an SMC-R link. The remote peer places TCP socket application data directly into the RMB that the local peer assigns to receive data for the TCP connection. The local peer then copies the data from the RMB into the receive buffer of the receiving socket application.
- Rendezvous processing
- The sequence of TCP connection management flows that are required to establish SMC-R communications between two peers.
- RMB element (RMBE)
- The specific portion of an RMB that is associated with a specific TCP connection. Each RMB is partitioned into RMBEs.
- RoCE environments
- Depending on the level of hardware that is used, the 10GbE RoCE Express feature operates in
either a shared or a dedicated RoCE environment.
- Dedicated RoCE environment
- A dedicated RoCE environment applies to an IBM zEnterprise® EC12 (zEC12) with driver 15, or an IBM zEnterprise BC12 (zBC12). In this environment, only a single operating system instance can use a physical RoCE feature. Multiple operating system instances cannot concurrently share the feature.
- Shared RoCE environment
- A shared RoCE environment applies to an IBM z13 (z13) or later system. In this environment, multiple operating system instances can concurrently use or share the same physical RoCE feature. With IBM z13 (z13) or later systems, the RoCE Express feature operates in a shared environment even if only one operating system instance is configured to use the feature.
- SMC-R link
- A logical point-to-point link between two virtual servers that is used for SMC-R communications.
- SMC-R link group
- A logical grouping of equal SMC-R links between two communicating peers.
- Staging buffer
- Memory that the TCP/IP stack allocates for outbound SMC-R data. Staging buffers are not associated with specific SMC-R links or link groups, and are used by all TCP connections that traverse SMC-R links on this stack. Only local applications access the staging buffer storage.