The vcfsh and vcocf services provide transfer of

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Unformatted text preview: Frames of a Virtual Channel. The MC_FSH and MC_OCF Services provide transfer of fixed-length SDUs synchronized with the release of Transfer Frames of a Master Channel. These services do not guarantee completeness but may signal gaps in the sequence of SDUs delivered to the receiving user. In a Virtual or Master Channel that provides one of the above services, only one user can use this service, and SDUs from different users are not multiplexed together within the Virtual or Master Channel. However, one or more users of the Packet or Virtual Channel Access Service may coexist in the Virtual or Master Channel used to support this service. 3.3.5.3 Services to Transfer Short, Fixed-Length Data Provided by AOS-SDLP The AOS-SDLP provides two services to transfer sequences of short, fixed-length SDUs: the VC_OCF Service and the Insert Service. The VC_OCF Service provides transfer of fixed-length SDUs synchronized with the release of Transfer Frames of a Virtual Channel. The Insert Service provides transfer of fixed-length SDUs synchronized with the release of Transfer Frames of a Physical Channel. These services do not guarantee completeness but may signal gaps in the sequence of SDUs delivered to the receiving user. In a Virtual Channel that provides the VC_OCF Service or in a Physical Channel that provides the Insert Service, only one user can use this service, and SDUs from different users are not multiplexed together within the Virtual or Physical Channel. However, one or more users of the Packet or VCA Service may coexist in the Virtual or Physical Channel used to support this service. CCSDS 130.2-G-1 Page 3-10 December 2007 CCSDS REPORT CONCERNING THE SPACE DATA LINK PROTOCOLS 3.3.6 SERVICES TO TRANSFER FRAMES The Space Data Link Protocols each have two services to transfer Transfer Frames over a space link: the Virtual Channel Frame (VCF) Service and the Master Channel Frame (MCF) Service. Since Transfer Frames are generated by the Space Data Link Protocols, these services are used by entities of the Space Data Link Protocols, not by entities of protocols of higher layers as is the case for the other services. The VCF (or MCF) Service provides transfer of a sequence of Transfer Frames, created by an independent protocol entity of the same protocol, on a Virtual (or Master) Channel across a space link. In a Virtual or Master Channel that provides the VCF or MCF Service, only one user can use the service, and SDUs from different users are not multiplexed together within the Virtual or Master Channel. The VCF and MCF Services provided by the TC-SDLP do not guarantee completeness. The service provider does not make any distinction between Type-A and Type-B Services (see 3.2.2.2) for SDUs supplied by the user. The user should perform necessary procedures to provide Type-A and Type-B Services. The VCF and MCF Services provided by the TM-SDLP and AOS-SDLP do not guarantee completeness but may signal gaps in the sequence of SDUs delivered to the receiving user. Transfer Frames supplied as SDUs to these services must have the same length as those generated by the service provider...
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