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that carries Packets.
18.104.22.168 The Packet Extraction Function shall be used to extract Packets from the Data Field
of Transfer Frames received from the Virtual Channel Reception Function. The First Header
Pointer, received from the Virtual Channel Reception Function together with the Data Field,
shall be used in conjunction with the length field of each Packet contained within the Data
Field to provide the delimiting information needed to extract Packets.
22.214.171.124 If the last Packet removed from the Data Field is incomplete, then the Packet
Extraction Function shall retrieve the remainder from the beginning of the next Data Field
received on the same Virtual Channel.
NOTE – The First Header Pointer for the next Data Field is used to determine the length
of the remainder, and hence the beginning of the next Packet to be extracted.
126.96.36.199 If the calculated location of the beginning of the first Packet is not consistent with
the location indicated by the First Header Pointer, then the Packet Extraction Function shall
assume that the First Header Pointer is correct, and shall continue the extraction based on that
assumption. CCSDS 132.0-B-1 Page 4-22 September 2003 CCSDS RECOMMENDATION FOR TM SPACE DATA LINK PROTOCOL 188.8.131.52 Extracted Packets shall be delivered to the users on the basis of the PVN in their
header. Incomplete Packets are not required to be delivered in cross support situations.
NOTE – Idle Packets are discarded. Data Fields that contain only Idle Data are also
184.108.40.206 An abstract model of the Packet Extraction Function is illustrated in figure 4-13.
User with PVN M Packet Service
User with PVN N Packets Packet
Channel Packets Discard Idle Packets
Demultiplexing and Extraction
Virtual Channel Reception Function Figure 4-13: Abstract Model of Packet Extraction Function
4.3.3 VIRTUAL CHANNEL RECEPTION FUNCTION
220.127.116.11 The Virtual Channel Reception Function shall be used to decommutate fields of
Transfer Frames of a Virtual Channel.
NOTE – There is an instance of the Virtual Channel Reception Function for each Virtual
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This document was uploaded on 03/06/2014.
- Spring '14