1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
|
# Handover between cells, intra-BSC
msc {
hscale=3;
ms [label="MS via BTS"], bsc_lchan[label="BSC lchan FSM"], bsc_gscon[label="BSC conn FSM"],
bsc_mgcp[label="BSC mgcp FSM"], mgw_msc[label="MGW/MSC"];
ms note mgw_msc [label="intra-BSC Handover sequence"];
bsc_gscon abox bsc_gscon [label="ST_ACTIVE"];
bsc_gscon box bsc_gscon [label="bsc_handover_start(): init conn->ho"];
bsc_gscon -> bsc_gscon [label="GSCON_EV_HO_START (intra-BSC)"];
bsc_gscon abox bsc_gscon [label="ST_HANDOVER_\nWAIT_LCHAN"];
bsc_lchan <- bsc_gscon [label="lchan_activate(lchan, FOR_HANDOVER)"];
...;
--- [label="on lchan FSM error or timeout"];
bsc_lchan -> bsc_gscon [label="GSCON_EV_LCHAN_ALLOC_ERROR"];
bsc_gscon box bsc_gscon [label="handover_end(fail)"];
ms note bsc_gscon [label="MS happily continues on the old lchan."];
bsc_gscon abox bsc_gscon [label="ST_ACTIVE"];
--- [label="END: 'on error'"];
...;
...;
--- [label="IF lchan FSM decides that it is an lchan for speech"];
bsc_lchan -> bsc_gscon [label="GSCON_EV_ENSURE_MGW_ENDPOINT"];
--- [label="IF there is an MGW endpoint for the BTS already (conn->user_plane.fi_bts)"];
bsc_gscon box bsc_gscon [label="handover_created_mgw_endpoint = false"];
bsc_gscon -> bsc_lchan [label="LCHAN_EV_MGW_ENDPOINT_AVAILABLE"];
--- [label="ELSE: no MGW endpoint for the BTS side yet"];
bsc_gscon abox bsc_gscon [label="ST_HANDOVER_\nWAIT_CRCX_BTS"];
bsc_gscon box bsc_gscon [label="handover_created_mgw_endpoint = true"];
bsc_gscon -> bsc_mgcp [label="mgcp_conn_create()"];
bsc_mgcp => mgw_msc [label="CRCX (for BTS)"];
bsc_mgcp abox bsc_mgcp [label="ST_CRCX_RESP (MGCP_MGW_TIMEOUT = 4s)"];
bsc_gscon note bsc_mgcp [label="conn FSM relies on mgcp FSM timeout"];
...;
--- [label="On Timeout"];
bsc_mgcp note bsc_mgcp [label="On timeout, the MGCP FSM will terminate, emitting the parent_term
event set upon mgcp_conn_create():"];
bsc_mgcp -> bsc_gscon [label="GSCON_EV_MGW_FAIL_BTS"];
bsc_gscon note bsc_gscon [label="GSCON_EV_MGW_FAIL_BTS is handled by the conn FSM allstate
handler. It sets conn->user_plane.fi_bts = NULL."];
bsc_gscon -> bsc_lchan [label="LCHAN_EV_MGW_ENDPOINT_ERROR"];
bsc_lchan note bsc_gscon [label="conn FSM error handler exits and relies on the lchan FSM
signalling error, which should actually happen immediately:"];
bsc_gscon <- bsc_lchan [label="GSCON_EV_LCHAN_ALLOC_ERROR"];
bsc_gscon box bsc_gscon [label="handover_end(fail)"];
--- [label="IF handover_created_mgw_endpoint == true"];
bsc_gscon -> bsc_mgcp [label="mgcp_conn_delete()"];
---;
ms note bsc_gscon [label="MS happily continues on the old lchan."];
bsc_gscon abox bsc_gscon [label="ST_ACTIVE"];
--- [label="END: 'On Timeout'"];
...;
bsc_mgcp <= mgw_msc [label="CRCX OK (for BTS)"];
bsc_mgcp box bsc_mgcp [label="libosmo-mgcp-client fsm_crcx_resp_cb()"];
bsc_mgcp abox bsc_mgcp [label="ST_READY"];
bsc_mgcp -> bsc_gscon [label="GSCON_EV_MGW_CRCX_RESP_BTS"];
bsc_gscon abox bsc_gscon [label="ST_HANDOVER_\nWAIT_LCHAN"];
bsc_gscon -> bsc_lchan [label="LCHAN_EV_MGW_ENDPOINT_AVAILABLE"];
--- [label="END: lchan FSM decides that it is an lchan for speech"];
...;
...;
bsc_lchan -> bsc_gscon [label="GSCON_EV_LCHAN_ACTIVE"];
bsc_gscon abox bsc_gscon [label="ST_HANDOVER_\nWAIT_DETECT\nT3103"];
bsc_gscon box bsc_gscon [label="gsm48_send_ho_cmd()"];
ms <= bsc_gscon [label="RR Handover Command"];
...;
--- [label="On timeout"];
bsc_lchan <- bsc_gscon [label="NEW lchan: LCHAN_EV_RELEASE"];
ms <=> bsc_lchan [label="release procedure (async)"];
bsc_gscon box bsc_gscon [label="handover_end(fail)"];
--- [label="IF handover_created_mgw_endpoint == true"];
bsc_gscon -> bsc_mgcp [label="mgcp_conn_delete()"];
---;
ms note bsc_gscon [label="MS happily continues on the old lchan."];
bsc_gscon abox bsc_gscon [label="ST_ACTIVE"];
--- [label="END: On timeout"];
...;
ms => bsc_gscon [label="RR Handover Detect"];
bsc_gscon abox bsc_gscon [label="ST_HANDOVER_\nWAIT_MDCX_BTS\ncontinue T3103"];
bsc_gscon -> bsc_lchan [label="OLD lchan: LCHAN_EV_RELEASE"];
ms <=> bsc_lchan [label="release procedure (async)"];
bsc_lchan note bsc_gscon [label="officially take over new lchan: conn->lchan = ho->new_lchan"];
bsc_gscon -> bsc_mgcp [label="mgcp_conn_modify()"];
bsc_mgcp note bsc_mgcp [label="mgcp FSM that was established for old lchan, for BTS side"];
bsc_mgcp abox bsc_mgcp [label="ST_MDCX_RESP"];
bsc_mgcp => mgw_msc [label="MDCX (for BTS)"];
...;
--- [label="Should the Handover Complete arrive early"];
ms => bsc_gscon [label="RR Handover Complete"];
bsc_gscon box bsc_gscon [label="handover_complete_received = true"];
---;
...;
--- [label="On timeout of the mgcp FSM"];
bsc_gscon note mgw_msc [label="MGCP FSM terminates"];
bsc_gscon <- bsc_mgcp [label="GSCON_EV_MGW_FAIL_BTS"];
bsc_lchan note bsc_gscon [label="The phone has already taken on the new lchan, but now we happen
to not be able to use it. The only sensible thing is to end the conn."];
bsc_gscon abox bsc_gscon [label="ST_WAIT_CLEAR_CMD"];
bsc_gscon => mgw_msc [label="BSSMAP Clear Request\n(Equipment Failure)"];
bsc_lchan <- bsc_gscon [label="NEW lchan: LCHAN_EV_RELEASE"];
ms <=> bsc_lchan [label="release procedure (async)"];
bsc_gscon -> bsc_mgcp [label="mgcp_conn_delete()"];
...;
bsc_mgcp <= mgw_msc [label="MDCX OK"];
bsc_mgcp abox bsc_mgcp [label="ST_READY"];
bsc_mgcp -> bsc_gscon [label="GSCON_EV_MGW_MDCX_RESP_BTS"];
--- [label="IF !handover_complete_received"];
bsc_gscon abox bsc_gscon [label="ST_HANDOVER_\nWAIT_COMPLETE\ncontinue T3103"];
--- [label="ELSE"];
bsc_gscon -> bsc_gscon [label="gscon_handover_post_complete()"];
---;
...;
ms => bsc_gscon [label="RR Handover Complete"];
bsc_gscon box bsc_gscon [label="gscon_handover_post_complete()"];
bsc_gscon note bsc_gscon [label="handover_end(success), conn->ho = NULL"];
bsc_gscon abox bsc_gscon [label="ST_ACTIVE"];
}
|
