add some notes about layer23 architecture
This commit is contained in:
parent
d4e118a7a0
commit
2ea6a02bf5
|
@ -0,0 +1,42 @@
|
|||
= OsmocomBB layer23 architecture =
|
||||
|
||||
layer23 is an (incomplete) MS-side implementation of the L2 and L3 GSM
|
||||
protocols as described in GSM TS 04.06, 04.08 and others.
|
||||
|
||||
== Interfaces ==
|
||||
|
||||
L1 (on the phone) uses the L1CTL protocol to talk with layer23 (on the PC).
|
||||
|
||||
L2 (inside layer23) uses the RSLms protocol to talk with the L3 (inside layer23)
|
||||
|
||||
|
||||
=== RSLms ===
|
||||
|
||||
RSLms is modeled after the GSM TS 08.58 Radio Subsystem Link protocol. Despite
|
||||
being designed for the network side, RSL seems a good match for the L2/L3
|
||||
interface inside a MS, too.
|
||||
|
||||
At least the RLL (Radio Link Layer) part of RSL is 100% as applicable to the MS
|
||||
side as it is for the ntwork side.
|
||||
|
||||
==== Lower interface (L2 to RSLms) ====
|
||||
|
||||
Layer2 calls rslms_sendmsg() with a msgb that has the msgb->l2h pointing to a
|
||||
RSL header (struct abis_rsl_common_hdr).
|
||||
|
||||
==== Upper interface (L3 to RSLms) ====
|
||||
|
||||
Layer3 calls rslms_recvmsg() with a msgb that has the msgb->l2h pointing to a
|
||||
RSL header (struct abis_rsl_common_hdr).
|
||||
|
||||
There are utility functions like rslms_tx_rll_req() and rslms_tx_rsll_req_l3()
|
||||
for creating msgb's with the apropriate RSL/RLL headers.
|
||||
|
||||
|
||||
=== LAPDm ===
|
||||
|
||||
LAPDm is the GSM TS 04.06 protocol
|
||||
|
||||
The lower interface (to L1) is using L1CTL
|
||||
|
||||
The upper interface (to L3) is using RSLms
|
Loading…
Reference in New Issue