Real-Time Media Access Control Framework (RTmac)
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================================================
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Revision: 2.0
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This document describes the protocol header of the real-time media access
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control framework for RTnet. The actual control protocol is implemented by
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so-called disciplines, see related specifications.
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Frame Format
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============
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RTmac frames are identified by the hexadecimal Ethernet type 0x9021. All frame
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fields are encoded in network order (big endian). The version identifier of
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the RTmac header shall only be changed if the format becomes incompatible to
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the previous revision. Currently, this version field contains the hexadecimal
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value 0x02.
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RTmac Frame Header
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------------------
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+----------------------+---------------+---------------+
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| Type | Version: 0x02 | Flags |
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| (2 bytes) | (1 byte) | (1 byte) |
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+----------------------+---------------+---------------+
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Depending on the tunnelling flag, the type field either contains the
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identifier of the succeeding discipline frame or the Ethernet type of a
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tunnelled non-real-time packet introduced by this header.
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Flags are encoded as follows:
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Bit Number | Interpretation if set
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------------+---------------------------------------------------------------
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0 | tunnelling frame if set, otherwise discipline frame
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1-7 | <reserved>
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2004, Jan Kiszka <jan.kiszka-at-web.de>
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