Oracle SDN operates in one of two modes, depending on the fabric type in use:
For QDR fabrics supplied by the switch's fabric board, PVIs operate in reliable connection (RC) mode. This mode enables server-to-server communication within the QDR fabric. Communication occurs only within IB-connected servers on a virtual network that is an overlay (a PVI) on the IB fabric. RC-mode communication enables east-west traffic on the fabric, and this mode has different IB MTU sizes than UD mode. For more information, see Supported MTU Sizes.
For EDR fabrics supplied by the switch's fabric board, PVIs operate in unreliable datagram (UD) mode. This mode enables server-to-server communication from the fabric through a PVI to other parts of the network. In addition to east-west traffic, UD-mode communication enables north-south traffic to egress and ingress the fabric through a gateway uplink. This mode has different IB MTU sizes than RC mode. For more information, see Supported MTU Sizes.