43 lines
1.2 KiB
Plaintext
43 lines
1.2 KiB
Plaintext
= OsmocomBB layer23 architecture =
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layer23 is an (incomplete) MS-side implementation of the L2 and L3 GSM
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protocols as described in GSM TS 04.06, 04.08 and others.
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== Interfaces ==
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L1 (on the phone) uses the L1CTL protocol to talk with layer23 (on the PC).
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L2 (inside layer23) uses the RSLms protocol to talk with the L3 (inside layer23)
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=== RSLms ===
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RSLms is modeled after the GSM TS 08.58 Radio Subsystem Link protocol. Despite
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being designed for the network side, RSL seems a good match for the L2/L3
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interface inside a MS, too.
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At least the RLL (Radio Link Layer) part of RSL is 100% as applicable to the MS
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side as it is for the ntwork side.
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==== Lower interface (L2 to RSLms) ====
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Layer2 calls rslms_sendmsg() with a msgb that has the msgb->l2h pointing to a
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RSL header (struct abis_rsl_common_hdr).
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==== Upper interface (L3 to RSLms) ====
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Layer3 calls rslms_recvmsg() with a msgb that has the msgb->l2h pointing to a
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RSL header (struct abis_rsl_common_hdr).
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There are utility functions like rslms_tx_rll_req() and rslms_tx_rsll_req_l3()
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for creating msgb's with the appropriate RSL/RLL headers.
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=== LAPDm ===
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LAPDm is the GSM TS 04.06 protocol
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The lower interface (to L1) is using L1CTL
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The upper interface (to L3) is using RSLms
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