The JAS Reliable Data Delivery Protocol (JRDDP) uses the lower level SpaceWire data link layer to provide reliable packet delivery services to one or more higher level host application processes. This document specifies the functional requirements for JRDDP but does not specify the interfaces to the lower or higher level processes, which may be implementation dependent.
The JRDDP protocol includes several changes to the GRDDP standard.
|Added variable length source address||Accommodate larger and / or hierarchical network configurations|
|Increased CRC to 16-bits||Improve error detection capability for larger packet sizes|
|Added optional secondary header||Allow program specific modifications and growth of the protocol with only minimal changes to the specification baseline|
|Urgent messaging is now optional||Reliable data delivery is the primary focus of JRDDP and best-effort delivery can be handled by other protocols|
|Added version number||Facilitates detection of unsupported protocol variants|
|Added sequence flags||Facilitates fragmentation and reassembly of data buffers passed to/from JRDDP|
|Added close channel semantics||Facilitates resource reuse in a dynamic communications environment|
|Increased channel number to 16-bits||Expand the number of defined channels|
"Internal Standards developed by Sandia National Laboratories". Experience Base, Sandia National Laboratories, Albuquerque, NM, 0000.