October 31, 2003
SDP Frequently Asked Questions
Q1. What is SDP?
SDP stands for "Sockets Direct Protocol". As the name indicates, it is a wire protocol for direct communication between RDMA hardware and the application “sockets layer” that enables applications to directly benefit from the performance benefits derived from RDMA technology.
Q2. What are “sockets”?
Sockets are a standard programming interface used to communicate with TCP/IP from applications.
Q3. What is the purpose of SDP?
SDP enables Internet applications to transparently take advantage of the performance advantages of the RDMA (Remote Direct Memory Access) protocol suite (RDMAP/DDP/MPA).
Q4. What are the advantages of SDP?
SDP enables internet applications to take advantage of the low-latency, high-bandwidth performance benefits of RDMA, including Direct Data Placement and Kernel Bypass.
Q5. What is SDP replacing?
SDP emulates sockets streaming semantics over the RDMA interface. It does not replace any component, but instead emulates sockets semantics to allow applications to gain the performance benefits of RDMA without changing any application code which relies on sockets today.
Q6. How is WSD related to SDP?
WinSock Direct Protocol (WSD, a.k.a. WSDP) is the predecessor to SDP. Support for WSD is currently shipping in Microsoft Server Operating Systems.
Q7. Is the RDMA Consortium planning any additional specifications?
No, the SDP specification is the final specification produced by the RDMA Consortium. The delivery of iSER, SDP, the RDMA wire-protocol suite and the Verbs Specifications complete the family of protocols necessary to enable deployment of RDMA based networking, Inter-Process Communication (IPC), and storage infrastructures.
Q8. What is the plan for the RDMAC now that the specs are complete?
The consortium members will continue to address Errata for the RDMA Consortium specifications. The members of the RDMAC will continue to work with the IETF on approval of the RDMA suite of specifications.
Q9. Will the SDP specification be submitted to the IETF?
Yes, the RDMAC will submit the SDP specification to the IETF as a proposed informational RFC to increase familiarity of the SDP protocol with the IETF.
Q10. When will RNIC hardware become available?
Specific details on availability of RNIC hardware need to come from RNIC vendors. In general, we expect RDMA solutions to be available in 2004.
Q11. When will operating systems support SDP?
Specific details on availability of SDP need to come from OS vendors.
Q12. Who should customers contact for information on RDMA products?
Customers should contact their respective vendors.
Q13. Where can I get additional information on the RDMA protocol and SDP?
Additional information is available at the RDMA Consortium website which is located at www.rdmaconsortium.org.