Unformatted text preview: e First Header
Pointer Field and three other bits of the Transfer Frame Status Field: the Packet
Order Flag (1 bit), and Segment Length ID (2 bits). These are undefined by
CCSDS when a Virtual Channel is used to transfer VCA_SDUs.
126.96.36.199 GVCID The GVCID parameter shall contain a GVCID that indicates the Virtual Channel through
which the VCA_SDU is to be transferred.
NOTE – The GVCID parameter is the SAP address of the VCA Service.
188.8.131.52 VCA_SDU Loss Flag The VCA_SDU Loss Flag is an optional parameter that may be used to notify the user at the
receiving end of the VCA Service that a sequence discontinuity has been detected and that
one or more VCA_SDUs have been lost. If implemented, the flag shall be derived by
examining the Virtual Channel Frame Count in the Transfer Frames. CCSDS 132.0-B-1 Page 3-7 September 2003 CCSDS RECOMMENDATION FOR TM SPACE DATA LINK PROTOCOL 3.4.3 VCA SERVICE PRIMITIVES
184.108.40.206 General The service primitives associated with the VCA Service are:
220.127.116.11 VCA.request 18.104.22.168.1 Function At the sending end, the VCA Service user shall pass a VCA.request primitive to the service
provider to request that a VCA_SDU be transferred to the user at the receiving end through
the specified Virtual Channel.
NOTE – The VCA.request primitive shall be the service request primitive for the VCA
22.214.171.124.2 Semantics The VCA.request primitive shall provide parameters as follows:
VCA.request 126.96.36.199.3 (VCA_SDU,
VCA Status Fields,
GVCID) When Generated The VCA.request primitive shall be passed to the service provider to request it to send the
188.8.131.52.4 Effect On Receipt Receipt of the VCA.request primitive shall cause the service provider to transfer the
184.108.40.206.5 Additional Comments
The VCA.request primitive shall be used to transfer VCA_SDUs across the space link on the
specified Virtual Channel. CCSDS 132.0-B-1 Page 3-8 September 2003 CCSDS RECOMMENDATION FOR TM SPACE DATA LINK PROTOCOL 220.127.116.11 VCA.indication 18.104.22.168.1 Function At the sending end, the service provider shall pas...
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- Spring '14
- Space Exploration, European Space Agency, Protocol data unit