Configuration details for using RDMA-capable Ethernet ports for node-to-node communications
Before you configure a system to use RDMA-capable Ethernet ports for node-to-node communications, consider the following recommendations.
For systems that use RDMA-capable Ethernet ports for node-to-node communication, the system has
the following limitations:
- Only IPv4 addresses are supported on RDMA-capable Ethernet ports.
- Only the default value of 1500 is supported for maximum transmission unit (MTU) for node-to-node communications that use RDMA-capable Ethernet ports.
- Port masking is not supported on RDMA-capable Ethernet ports. Due to this limitation, do not exceed the maximum of four ports for node-to-node communications.
- Hot-spare nodes are not supported on systems that use RDMA-capable Ethernet ports for node-to-node communications.
- Node-to-node communications that use RDMA-capable Ethernet ports are not supported in a network configuration that contains more than 2 hops in the fabric of switches.
- Some environments might not include a stretched layer 2 subnet. In such scenarios, a layer 3 network such as in standard topologies or long-distance RDMA node-to-node HyperSwap® configurations is applicable. To support the layer 3 Ethernet network, the unicast discovery method can be employed for RDMA node-to-node communication. This method relies on unicast-based fabric discovery rather than multicast discovery. To configure unicast discovery, see the addnodediscoverysubnet, rmnodediscoverysubnet, or lsnodediscoverysubnet commands.
- Only certain models of the system support RDMA-capable Ethernet ports for node-to-node
communications. For a list of the system hardware models that support RDMA-capable Ethernet ports,
see the following website:
http://www-03.ibm.com/systems/support/storage/ssic/interoperability.wss
For other information about using RDMA-capable Ethernet ports on the system, go to the following website and search for Configuration Limits and Restrictions: