DRBD’s replication and synchronization framework socket layer supports multiple low-level transports:
TCP over IPv4. This is the canonical implementation, and DRBD’s default. It may be used on any system that has IPv4 enabled.
TCP over IPv6. When configured to use standard TCP sockets for replication and synchronization, DRBD can use also IPv6 as its network protocol. This is equivalent in semantics and performance to IPv4, albeit using a different addressing scheme.
SDP. SDP is an implementation of BSD-style sockets for RDMA capable transports such as InfiniBand. SDP is available as part of the OFED stack for most current distributions. SDP uses and IPv4-style addressing scheme. Employed over an InfiniBand interconnect, SDP provides a high-throughput, low-latency replication network to DRBD.
SuperSockets. SuperSockets replace the TCP/IP portions of the stack with a single, monolithic, highly efficient and RDMA capable socket implementation. DRBD can use this socket type for very low latency replication. SuperSockets must run on specific hardware which is currently available from a single vendor, Dolphin Interconnect Solutions.