Linux® on IBM® Z supports RDMA
over Converged Ethernet (RoCE) in the form of 10GbE RoCE Express features.
A 10GbE RoCE Express feature physically consists of a
Mellanox ConnectX-3 EN or Mellanox ConnectX-4
adapter. The adapters are two-port Ethernet adapters. On a mainframe, the mapping of ports to
function keys depend on the adapter hardware:
The two Mellanox ConnectX-3 EN adapter ports belong to the same function ID.
The two Mellanox ConnectX-4 adapter ports belong to different function IDs.
The RoCE support requires PCI Express support.
Using a RoCE device for SMC-R
SMC-R requires RoCE devices that are associated with network devices of TCP networks through a
PNET ID, for example through statements in the IOCDS.
The following figure illustrates how a RoCE device and a Ethernet device are associated by a
matching PNET ID. A communication peer has a similarly associated pair of an RoCE device and
Ethernet device. With this setup, the TCP connection can switch over to an SMC-R connection over the
SMC protocol. The communication peer can but need not be on the same CPC.Figure 1. A matching PNET ID associates RoCE devices and Ethernet device
