Indication packet gvcid packet version number packet

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Unformatted text preview: Quality Indicator (optional)) When Generated The PACKET.indication primitive shall be passed from the service provider to the Packet Service user at the receiving end to deliver a Packet. Effect On Receipt The effect of receipt of the PACKET.indication primitive by the Packet Service user is undefined. Additional Comments The PACKET.indication primitive shall be used to deliver Packets to the Packet Service user identified by the GVCID and Packet Version Number. Incomplete Packets may be delivered (optional). 3.4 VIRTUAL CHANNEL ACCESS (VCA) SERVICE 3.4.1 OVERVIEW OF VCA SERVICE The Virtual Channel Access (VCA) Service provides transfer of a sequence of privately formatted service data units of fixed length, along with status fields, across a space link. The service is unidirectional, either asynchronous or periodic, and sequence-preserving. The service does not guarantee completeness, but it may signal gaps in the sequence of service data units delivered to the receiving user. CCSDS 132.0-B-1 Page 3-6 September 2003 CCSDS RECOMMENDATION FOR TM SPACE DATA LINK PROTOCOL Only one user, identified with the GVCID of the Virtual Channel, can use this service on a Virtual Channel. Service data units from different users are not multiplexed together within one Virtual Channel. 3.4.2 VCA SERVICE PARAMETERS General The parameters used by the VCA Service primitives shall conform to the specifications contained in subsections through VCA_SDU NOTE – The VCA_SDU parameter is the service data unit transferred by the VCA Service. For restrictions on the VCA_SDUs transferred by the VCA Service, see 3.2.3. VCA Status Fields The Packet Order Flag (1 bit) and Segment Length ID (2 bits) may be used to convey information on the validity, sequence, or other status of the VCA_SDUs. Provision of this field is mandatory; semantics are user-optional. NOTE – The VCA Status Fields parameter consists of the Transfer Fram...
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This document was uploaded on 03/06/2014.

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