CCSDS 734.2-R-1, CCSDS Bundle Protocol Specification (Red ...

DRAFT CCSDS RECOMMENDED STANDARD FOR CCSDS BUNDLE PROTOCOL SPECIFICATION3 CCSDS PROFILE OF RFC 50503.1 GENERALThis document adopts the Bundle Protocol (BP) as specified in Internet RFC 5050(reference [1]), with the constraints and exceptions specified in section 3 of this document.3.2 COMPRESSED BUNDLE HEADER ENCODINGConformant implementations of the CCSDS Bundle Protocol shall implement the‘Compressed Bundle Header Encoding (CBHE)’ (reference [4]).NOTE – CBHE supports bit-efficient encoding of BP endpoint identifiers that use CBHEconformantschemes. Endpoints are identified by the combination of node numberand service number, both of which are Self-Delimiting Numeric Values (SDNVs).3.3 BUNDLE PROTOCOL EXTENDED CLASS OF SERVICEConformant implementations of the CCSDS Bundle Protocol shall implement the ‘ExtendedClass of Service (ECOS)’ block defined in annex B.NOTE – Spacecraft operations may require additional features beyond those identified inRFC 5050. One such feature is the expansion of the bundle process control flagsdesignated as ‘class-of-service’. ECOS provides the capability to prioritize orextend the service classes. Such uses include:– the creation of emergency or critical traffic;– expansion of traffic priorities reflective of a diverse user environment;– special handling of bundles.3.4 USE OF TIME IN SECTION 6.1 OF RFC 5050Where the spacecraft time system does not provide sufficient precision to support therequirements of RFC 5050 section 6.1, the precision of the onboard system shall be used.NOTE – Section 6.1 of RFC 5050 specifies that the time fields in administrative recordsuse seconds and nanoseconds since the start of year 2000. Spacecraft timesystems may not be able to provide meaningful values for the nanoseconds fieldsof these entries. In such a case the administrative time field shall support theprecision of the clock rate to the significant digits of the Command and DataHandling (C&DH) subsystem and will not drive requirements on the precision ofthe spacecraft clock.CCSDS 734.2-R-1 Page 3-1 February 2012