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Unformatted text preview: al Channel in a Physical Channel is identified by a GVCID. Therefore, a Virtual
Channel consists of Transfer Frames with the same GVCID.
All Transfer Frames with the same MCID on a Physical Channel constitute a Master Channel
(MC). A Master Channel consists of one or more Virtual Channels. In most cases, a
Physical Channel carries only Transfer Frames of a single MCID, and the Master Channel
will be identical with the Physical Channel. However, a Physical Channel may carry
Transfer Frames with multiple MCIDs (with the same TFVN). In such a case, the Physical
Channel consists of multiple Master Channels. A Physical Channel is identified with a
Physical Channel Name, which is set by management and not included in the header of
The relationships between these Channels are shown in figure 2-2. CCSDS 132.0-B-1 Page 2-2 September 2003 CCSDS RECOMMENDATION FOR TM SPACE DATA LINK PROTOCOL Virtual C hannel:
Identified b y G VC ID
Mas ter C hannel:
Identified b y MC ID Phy s ical C hannel:
Identified b y Phy s ical
C hannel Name Figure 2-2: Relationships Between Channels
2.1.4 PROTOCOL DESCRIPTION
The TM Space Data Link Protocol is described in terms of:
a) the services provided to the users;
b) the protocol data units; and
c) the procedures performed by the protocol.
The service definitions are given in the form of primitives, which present an abstract model
of the logical exchange of data and control information between the protocol entity and the
service user. The definitions of primitives are independent of specific implementation
The procedure specifications define the procedures performed by protocol entities for the
transfer of information between peer entities. The definitions of procedures are independent
of specific implementation methods or technologies.
This protocol specification also specifies the requirements for the underlying services
provided by the Channel Coding Sublayer and the Physical Layer.
2.2 OVERVIEW OF SERVICES 2.2.1 COMMON FEATURES OF SERVICES
The TM Space Data Link Protocol provides users with data transfer services. The...
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