Checking data integrity
A network interface device for connection to a data processing device and to a data network so as to provide an interface between the data processing device and the network for supporting the network of packets of a transport protocol, the network interface device being configured to: identify within the payloads of such packets data of a further protocol, the data of the further protocol comprising payload data of the further protocol and framing data of the further protocol, and the framing data including verification data for permitting the integrity of the payload data to be verified; on so identifying data of the further protocol, process at least the payload data for determining the integrity thereof and transmit to the data processing device at least some of the framing data and an indication of the result of the said processing.
1. A data processing system comprising:
a data processing device configured to perform transport protocol processing; and
a network interface device connected to the data processing device and configured to on receiving a data packet of the transport protocol:
identify within a payload of the data packet data of a further protocol, the data of the further protocol comprising payload data of the further protocol and framing data of the further protocol, the framing data of the further protocol including verification data for permitting the integrity of the payload data of the further protocol to be verified;
upon identifying the data of the further protocol, process the payload data of the further protocol so as to determine the integrity thereof; and
if the payload data of the further protocol is determined by said processing not to have integrity, then transmit to the data processing device header data of the data packet of the transport protocol and at least some of the framing data of the further protocol but not the payload data of the further protocol; and
otherwise, transmit to the data processing device the header data of the data packet of the transport protocol, the payload data of the further protocol and at least some of the framing data of the further protocol;
wherein the data processing device is further configured to:
on receiving the header data of the data packet of the transport protocol and at least some of the framing data of the further protocol but not the payload data of the further protocol, initiate a request for retransmission of the payload data of the further protocol; and
on receiving the header data of the data packet of the transport protocol, payload data of the further protocol and at least some of the framing data of the further protocol, process the payload and framing data of the further protocol and at least partially protocol process the header data of the data packet of the transport protocol.
2. A data processing system as claimed in claim 1 , wherein the network interface device is configured to process the payload data of the further protocol by applying a data verification algorithm to the payload data of the further protocol to form a verification result.
3. A data processing system as claimed in claim 2 , wherein the network interface device is configured to transmit the verification result to the data processing device with the at least some of the framing data of the further protocol.
4. A data processing system as claimed in claim 1 , wherein the network interface device is configured to transmit header data of the data packet of the transport protocol to the data processing device with the at least some of the framing data of the further protocol.
5. A data processing system as claimed in claim 2 , wherein the data verification algorithm is a cyclic redundancy check function.
6. A data processing system as claimed in claim 2 , wherein the data verification algorithm is an authentication function.
7. A data processing system as claimed in claim 1 , wherein the network interface device is configured to perform the transmission to the data processing device by transmitting data to a transport library supported by the data processing device.
8. A data processing system as claimed in claim 1 , wherein the transport protocol is the TCP (transmission control protocol) protocol.
9. A data processing system as claimed in claim 1 , wherein the further protocol is a protocol for remote direct memory access.
10. A data processing system as claimed in claim 9 , wherein the further protocol is such that it supports memory write instructions and the framing data of the further protocol includes information indicative of a memory address of the data processing device to which at least some of the payload data is intended to be written.
11. A data processing system as claimed in claim 10 , wherein the further protocol is the RDMA (remote direct memory access) or iSCSI (internet small computer serial interface) protocol.
12. A data processing system as claimed in claim 1 , wherein the network interface device is configured to provide an interface between the data processing device and a network.
13. A method for processing a data packet received over a network at a data processing system having a data processing device configured to perform transport protocol processing and a network interface device, the method comprising:
the network interface device, on receiving a data packet formed in accordance with a transport protocol:
identifying within a payload of the data packet data of a further protocol, the data of the further protocol comprising payload data of the further protocol and framing data of the further protocol, the framing data of the further protocol including verification data for permitting the integrity of the payload data to be verified;
upon identifying the data of the further protocol, processing the payload data of the further protocol so as to determine the integrity thereof; and
if the payload data of the further protocol is determined by said processing not to have integrity, then transmitting to the data processing device header data of the data packet of the transport protocol and at least some of the framing data of the further protocol but not the payload data of the further protocol; and
otherwise, transmitting to the data processing device the header data of the data packet of the transport protocol, the payload data of the further protocol and at least some of the framing data of the further protocol;
on receiving the header data of the data packet of the transport protocol and at least some of the framing data of the further protocol but not the payload data of the further protocol, initiate a request for retransmission of the payload data of the further protocol; and
on receiving the header data of the data packet of the transport protocol, payload data of the further protocol and at least some of the framing data of the further protocol, process the payload and framing data of the further protocol and at least partially protocol process the header data of the data packet of the transport protocol.
14. A method as claimed in claim 13 , wherein the network interface device is located between the data processing device and a network.