<p>pespin <strong>submitted</strong> this change.</p><p><a href="https://gerrit.osmocom.org/c/osmo-bsc/+/25006">View Change</a></p><div style="white-space:pre-wrap">Approvals:
Jenkins Builder: Verified
osmith: Looks good to me, but someone else must approve
pespin: Looks good to me, approved
</div><pre style="font-family: monospace,monospace; white-space: pre-wrap;">Introduce VTY option to forbid use of TCH for non-voicecall signalling<br><br>Usual allocation mechansim, when some signalling channel is needed,<br>first tries to reserve an SDCCH, and if all of them are exhausted, then<br>attempts to reserve a TCH as a last resort.<br>This, however, may cause TCH starvation under certain situations, for<br>instance if there high load on other services (LU, SMS, etc.).<br>Hence, it may be desirable for the operator to forbid reservation<br>of TCH slots once SDCCH become exhausted. This commit is thus adding a<br>VTY command which allows forbidding it. The default behavior (allow using<br>TCH timeslots when SDCCHs are exhausted) is kept as before.<br><br>The above mentioned prohibition is applied only to non-voicecall related<br>signalling services. That's because voicecall services will end up<br>requiring a TCH anyway, and forbidding reservation of TCH straighaway<br>when SDCCHs are exhausted would mean no voice calls could be initiated<br>while still TCHs would be available.<br><br>Related: SYS#5548<br>Change-Id: Ib08027125145df26602069bfb51847063b0ccc0c<br>---<br>M include/osmocom/bsc/bts.h<br>M include/osmocom/bsc/gsm_data.h<br>M src/osmo-bsc/abis_rsl.c<br>M src/osmo-bsc/bts.c<br>M src/osmo-bsc/bts_vty.c<br>M tests/osmo-bsc.vty<br>6 files changed, 67 insertions(+), 14 deletions(-)<br><br></pre><pre style="font-family: monospace,monospace; white-space: pre-wrap;"><span>diff --git a/include/osmocom/bsc/bts.h b/include/osmocom/bsc/bts.h</span><br><span>index 72ef8d9..1d566f5 100644</span><br><span>--- a/include/osmocom/bsc/bts.h</span><br><span>+++ b/include/osmocom/bsc/bts.h</span><br><span>@@ -454,6 +454,10 @@</span><br><span> * interference reported in RSL Resource Indication. */</span><br><span> bool chan_alloc_avoid_interf;</span><br><span> </span><br><span style="color: hsl(120, 100%, 40%);">+ /* When true (default), TCH can be allocated to serve</span><br><span style="color: hsl(120, 100%, 40%);">+ * non-voicecall-related signalling services when SDCCHs are exhausted */</span><br><span style="color: hsl(120, 100%, 40%);">+ bool chan_alloc_allow_tch_for_signalling;</span><br><span style="color: hsl(120, 100%, 40%);">+</span><br><span> enum neigh_list_manual_mode neigh_list_manual_mode;</span><br><span> /* parameters from which we build SYSTEM INFORMATION */</span><br><span> struct {</span><br><span>diff --git a/include/osmocom/bsc/gsm_data.h b/include/osmocom/bsc/gsm_data.h</span><br><span>index 0632944..5a20e72 100644</span><br><span>--- a/include/osmocom/bsc/gsm_data.h</span><br><span>+++ b/include/osmocom/bsc/gsm_data.h</span><br><span>@@ -419,6 +419,11 @@</span><br><span> GSM_CHREQ_REASON_PDCH,</span><br><span> };</span><br><span> </span><br><span style="color: hsl(120, 100%, 40%);">+static inline bool gsm_chreq_reason_is_voicecall(enum gsm_chreq_reason_t reason)</span><br><span style="color: hsl(120, 100%, 40%);">+{</span><br><span style="color: hsl(120, 100%, 40%);">+ return reason == GSM_CHREQ_REASON_EMERG || reason == GSM_CHREQ_REASON_CALL;</span><br><span style="color: hsl(120, 100%, 40%);">+}</span><br><span style="color: hsl(120, 100%, 40%);">+</span><br><span> /* lchans 0..3 are SDCCH in combined channel configuration,</span><br><span> use 4 as magic number for BCCH hack - see osmo-bts-../oml.c:opstart_compl() */</span><br><span> #define CCCH_LCHAN 4</span><br><span>diff --git a/src/osmo-bsc/abis_rsl.c b/src/osmo-bsc/abis_rsl.c</span><br><span>index 8e4916d..d5b0d53 100644</span><br><span>--- a/src/osmo-bsc/abis_rsl.c</span><br><span>+++ b/src/osmo-bsc/abis_rsl.c</span><br><span>@@ -2015,17 +2015,19 @@</span><br><span> * in the code below, all other channel requests will get an SDCCH first</span><br><span> * (if possible). */</span><br><span> </span><br><span style="color: hsl(0, 100%, 40%);">- if (!lchan) {</span><br><span style="color: hsl(0, 100%, 40%);">- LOG_BTS(bts, DRSL, LOGL_NOTICE, "CHAN RQD[%s]: no resources for %s 0x%x, retrying with %s\n",</span><br><span style="color: hsl(0, 100%, 40%);">- get_value_string(gsm_chreq_descs, rqd->reason), gsm_lchant_name(GSM_LCHAN_SDCCH),</span><br><span style="color: hsl(0, 100%, 40%);">- rqd->ref.ra, gsm_lchant_name(GSM_LCHAN_TCH_H));</span><br><span style="color: hsl(0, 100%, 40%);">- lchan = lchan_select_by_type(bts, GSM_LCHAN_TCH_H);</span><br><span style="color: hsl(0, 100%, 40%);">- }</span><br><span style="color: hsl(0, 100%, 40%);">- if (!lchan) {</span><br><span style="color: hsl(0, 100%, 40%);">- LOG_BTS(bts, DRSL, LOGL_NOTICE, "CHAN RQD[%s]: no resources for %s 0x%x, retrying with %s\n",</span><br><span style="color: hsl(0, 100%, 40%);">- get_value_string(gsm_chreq_descs, rqd->reason), gsm_lchant_name(GSM_LCHAN_SDCCH),</span><br><span style="color: hsl(0, 100%, 40%);">- rqd->ref.ra, gsm_lchant_name(GSM_LCHAN_TCH_F));</span><br><span style="color: hsl(0, 100%, 40%);">- lchan = lchan_select_by_type(bts, GSM_LCHAN_TCH_F);</span><br><span style="color: hsl(120, 100%, 40%);">+ if (gsm_chreq_reason_is_voicecall(rqd->reason) || bts->chan_alloc_allow_tch_for_signalling) {</span><br><span style="color: hsl(120, 100%, 40%);">+ if (!lchan) {</span><br><span style="color: hsl(120, 100%, 40%);">+ LOG_BTS(bts, DRSL, LOGL_NOTICE, "CHAN RQD[%s]: no resources for %s 0x%x, retrying with %s\n",</span><br><span style="color: hsl(120, 100%, 40%);">+ get_value_string(gsm_chreq_descs, rqd->reason), gsm_lchant_name(GSM_LCHAN_SDCCH),</span><br><span style="color: hsl(120, 100%, 40%);">+ rqd->ref.ra, gsm_lchant_name(GSM_LCHAN_TCH_H));</span><br><span style="color: hsl(120, 100%, 40%);">+ lchan = lchan_select_by_type(bts, GSM_LCHAN_TCH_H);</span><br><span style="color: hsl(120, 100%, 40%);">+ }</span><br><span style="color: hsl(120, 100%, 40%);">+ if (!lchan) {</span><br><span style="color: hsl(120, 100%, 40%);">+ LOG_BTS(bts, DRSL, LOGL_NOTICE, "CHAN RQD[%s]: no resources for %s 0x%x, retrying with %s\n",</span><br><span style="color: hsl(120, 100%, 40%);">+ get_value_string(gsm_chreq_descs, rqd->reason), gsm_lchant_name(GSM_LCHAN_SDCCH),</span><br><span style="color: hsl(120, 100%, 40%);">+ rqd->ref.ra, gsm_lchant_name(GSM_LCHAN_TCH_F));</span><br><span style="color: hsl(120, 100%, 40%);">+ lchan = lchan_select_by_type(bts, GSM_LCHAN_TCH_F);</span><br><span style="color: hsl(120, 100%, 40%);">+ }</span><br><span> }</span><br><span> if (!lchan) {</span><br><span> LOG_BTS(bts, DRSL, LOGL_NOTICE, "CHAN RQD[%s]: no resources for %s 0x%x\n",</span><br><span>diff --git a/src/osmo-bsc/bts.c b/src/osmo-bsc/bts.c</span><br><span>index ec29ac8..c0d6634 100644</span><br><span>--- a/src/osmo-bsc/bts.c</span><br><span>+++ b/src/osmo-bsc/bts.c</span><br><span>@@ -245,6 +245,7 @@</span><br><span> bts->neigh_list_manual_mode = NL_MODE_AUTOMATIC;</span><br><span> bts->early_classmark_allowed_3g = true; /* 3g Early Classmark Sending controlled by bts->early_classmark_allowed param */</span><br><span> bts->si_unused_send_empty = true;</span><br><span style="color: hsl(120, 100%, 40%);">+ bts->chan_alloc_allow_tch_for_signalling = true;</span><br><span> bts->si_common.cell_sel_par.cell_resel_hyst = 2; /* 4 dB */</span><br><span> bts->si_common.cell_sel_par.rxlev_acc_min = 0;</span><br><span> bts->si_common.si2quater_neigh_list.arfcn = bts->si_common.data.earfcn_list;</span><br><span>diff --git a/src/osmo-bsc/bts_vty.c b/src/osmo-bsc/bts_vty.c</span><br><span>index b8b9f6c..3695d28 100644</span><br><span>--- a/src/osmo-bsc/bts_vty.c</span><br><span>+++ b/src/osmo-bsc/bts_vty.c</span><br><span>@@ -565,6 +565,25 @@</span><br><span> return CMD_SUCCESS;</span><br><span> }</span><br><span> </span><br><span style="color: hsl(120, 100%, 40%);">+DEFUN_ATTR(cfg_bts_chan_alloc_allow_tch_for_signalling,</span><br><span style="color: hsl(120, 100%, 40%);">+ cfg_bts_chan_alloc_allow_tch_for_signalling_cmd,</span><br><span style="color: hsl(120, 100%, 40%);">+ "channel allocator allow-tch-for-signalling (0|1)",</span><br><span style="color: hsl(120, 100%, 40%);">+ "Channel Allocator\n" "Channel Allocator\n"</span><br><span style="color: hsl(120, 100%, 40%);">+ "Configure whether TCH/H or TCH/F channels can be used to serve non-call-related signalling if SDCCHs are exhausted\n"</span><br><span style="color: hsl(120, 100%, 40%);">+ "Forbid use of TCH for non-call-related signalling purposes\n"</span><br><span style="color: hsl(120, 100%, 40%);">+ "Allow use of TCH for non-call-related signalling purposes (default)\n",</span><br><span style="color: hsl(120, 100%, 40%);">+ CMD_ATTR_IMMEDIATE)</span><br><span style="color: hsl(120, 100%, 40%);">+{</span><br><span style="color: hsl(120, 100%, 40%);">+ struct gsm_bts *bts = vty->index;</span><br><span style="color: hsl(120, 100%, 40%);">+</span><br><span style="color: hsl(120, 100%, 40%);">+ if (!strcmp(argv[0], "0"))</span><br><span style="color: hsl(120, 100%, 40%);">+ bts->chan_alloc_allow_tch_for_signalling = false;</span><br><span style="color: hsl(120, 100%, 40%);">+ else</span><br><span style="color: hsl(120, 100%, 40%);">+ bts->chan_alloc_allow_tch_for_signalling = true;</span><br><span style="color: hsl(120, 100%, 40%);">+</span><br><span style="color: hsl(120, 100%, 40%);">+ return CMD_SUCCESS;</span><br><span style="color: hsl(120, 100%, 40%);">+}</span><br><span style="color: hsl(120, 100%, 40%);">+</span><br><span> #define RACH_STR "Random Access Control Channel\n"</span><br><span> </span><br><span> DEFUN_USRATTR(cfg_bts_rach_tx_integer,</span><br><span>@@ -3736,6 +3755,8 @@</span><br><span> VTY_NEWLINE);</span><br><span> if (bts->chan_alloc_avoid_interf)</span><br><span> vty_out(vty, " channel allocator avoid-interference 1%s", VTY_NEWLINE);</span><br><span style="color: hsl(120, 100%, 40%);">+ if (!bts->chan_alloc_allow_tch_for_signalling)</span><br><span style="color: hsl(120, 100%, 40%);">+ vty_out(vty, " channel allocator allow-tch-for-signalling 0%s", VTY_NEWLINE);</span><br><span> vty_out(vty, " rach tx integer %u%s",</span><br><span> bts->si_common.rach_control.tx_integer, VTY_NEWLINE);</span><br><span> vty_out(vty, " rach max transmission %u%s",</span><br><span>@@ -4018,6 +4039,7 @@</span><br><span> install_element(BTS_NODE, &cfg_bts_oml_e1_tei_cmd);</span><br><span> install_element(BTS_NODE, &cfg_bts_challoc_cmd);</span><br><span> install_element(BTS_NODE, &cfg_bts_chan_alloc_interf_cmd);</span><br><span style="color: hsl(120, 100%, 40%);">+ install_element(BTS_NODE, &cfg_bts_chan_alloc_allow_tch_for_signalling_cmd);</span><br><span> install_element(BTS_NODE, &cfg_bts_rach_tx_integer_cmd);</span><br><span> install_element(BTS_NODE, &cfg_bts_rach_max_trans_cmd);</span><br><span> install_element(BTS_NODE, &cfg_bts_rach_max_delay_cmd);</span><br><span>diff --git a/tests/osmo-bsc.vty b/tests/osmo-bsc.vty</span><br><span>index 1d859c3..3bc2707 100644</span><br><span>--- a/tests/osmo-bsc.vty</span><br><span>+++ b/tests/osmo-bsc.vty</span><br><span>@@ -163,14 +163,19 @@</span><br><span> allocator Channel Allocator</span><br><span> </span><br><span> OsmoBSC(config-net-bts)# channel allocator ?</span><br><span style="color: hsl(0, 100%, 40%);">- ascending Allocate Timeslots and Transceivers in ascending order</span><br><span style="color: hsl(0, 100%, 40%);">- descending Allocate Timeslots and Transceivers in descending order</span><br><span style="color: hsl(0, 100%, 40%);">- avoid-interference Configure whether reported interference levels from RES IND are used in channel allocation</span><br><span style="color: hsl(120, 100%, 40%);">+ ascending Allocate Timeslots and Transceivers in ascending order</span><br><span style="color: hsl(120, 100%, 40%);">+ descending Allocate Timeslots and Transceivers in descending order</span><br><span style="color: hsl(120, 100%, 40%);">+ avoid-interference Configure whether reported interference levels from RES IND are used in channel allocation</span><br><span style="color: hsl(120, 100%, 40%);">+ allow-tch-for-signalling Configure whether TCH/H or TCH/F channels can be used to serve non-call-related signalling if SDCCHs are exhausted</span><br><span> </span><br><span> OsmoBSC(config-net-bts)# channel allocator avoid-interference ?</span><br><span> 0 Ignore interference levels (default). Always assign lchans in a deterministic order.</span><br><span> 1 In channel allocation, prefer lchans with less interference.</span><br><span> </span><br><span style="color: hsl(120, 100%, 40%);">+OsmoBSC(config-net-bts)# channel allocator allow-tch-for-signalling ?</span><br><span style="color: hsl(120, 100%, 40%);">+ 0 Forbid use of TCH for non-call-related signalling purposes</span><br><span style="color: hsl(120, 100%, 40%);">+ 1 Allow use of TCH for non-call-related signalling purposes (default)</span><br><span style="color: hsl(120, 100%, 40%);">+</span><br><span> OsmoBSC(config-net-bts)# show running-config</span><br><span> ... !channel allocator avoid-interference</span><br><span> OsmoBSC(config-net-bts)# channel allocator avoid-interference 1</span><br><span>@@ -184,3 +189,17 @@</span><br><span> OsmoBSC(config-net-bts)# channel allocator avoid-interference 0</span><br><span> OsmoBSC(config-net-bts)# show running-config</span><br><span> ... !channel allocator avoid-interference</span><br><span style="color: hsl(120, 100%, 40%);">+</span><br><span style="color: hsl(120, 100%, 40%);">+OsmoBSC(config-net-bts)# show running-config</span><br><span style="color: hsl(120, 100%, 40%);">+... !channel allocator allow-tch-for-signalling</span><br><span style="color: hsl(120, 100%, 40%);">+OsmoBSC(config-net-bts)# channel allocator allow-tch-for-signalling 0</span><br><span style="color: hsl(120, 100%, 40%);">+OsmoBSC(config-net-bts)# show running-config</span><br><span style="color: hsl(120, 100%, 40%);">+...</span><br><span style="color: hsl(120, 100%, 40%);">+ bts 0</span><br><span style="color: hsl(120, 100%, 40%);">+...</span><br><span style="color: hsl(120, 100%, 40%);">+ channel allocator allow-tch-for-signalling 0</span><br><span style="color: hsl(120, 100%, 40%);">+...</span><br><span style="color: hsl(120, 100%, 40%);">+</span><br><span style="color: hsl(120, 100%, 40%);">+OsmoBSC(config-net-bts)# channel allocator allow-tch-for-signalling 1</span><br><span style="color: hsl(120, 100%, 40%);">+OsmoBSC(config-net-bts)# show running-config</span><br><span style="color: hsl(120, 100%, 40%);">+... !channel allocator allow-tch-for-signalling</span><br><span></span><br></pre><p>To view, visit <a href="https://gerrit.osmocom.org/c/osmo-bsc/+/25006">change 25006</a>. 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<div style="display:none"> Gerrit-Project: osmo-bsc </div>
<div style="display:none"> Gerrit-Branch: master </div>
<div style="display:none"> Gerrit-Change-Id: Ib08027125145df26602069bfb51847063b0ccc0c </div>
<div style="display:none"> Gerrit-Change-Number: 25006 </div>
<div style="display:none"> Gerrit-PatchSet: 4 </div>
<div style="display:none"> Gerrit-Owner: pespin <pespin@sysmocom.de> </div>
<div style="display:none"> Gerrit-Reviewer: Jenkins Builder </div>
<div style="display:none"> Gerrit-Reviewer: neels <nhofmeyr@sysmocom.de> </div>
<div style="display:none"> Gerrit-Reviewer: osmith <osmith@sysmocom.de> </div>
<div style="display:none"> Gerrit-Reviewer: pespin <pespin@sysmocom.de> </div>
<div style="display:none"> Gerrit-MessageType: merged </div>