https://projects.osmocom.org/https://projects.osmocom.org/favicon.ico?16647414092018-03-19T00:17:54ZOpen Source Mobile CommunicationsOsmoBTS - Feature #3075: do not transmit SI13 when the PCU is not connectedhttps://projects.osmocom.org/issues/3075?journal_id=83342018-03-19T00:17:54Zneelsnhofmeyr@sysmocom.de
<ul><li><strong>Related to</strong> <i><a class="issue tracker-1 status-6 priority-2 priority-default closed" href="/issues/3042">Bug #3042</a>: in the presence of two BTS, a subscribed phone seems compelled to repeatedly Location Update every ~15 seconds</i> added</li></ul> OsmoBTS - Feature #3075: do not transmit SI13 when the PCU is not connectedhttps://projects.osmocom.org/issues/3075?journal_id=83362018-03-19T11:30:08Zlaforge
<ul></ul><p>Even more important than not sending SI13 is to not send the indication that SI13 <br />is present (In SI3 or SI4, AFAIR).</p> OsmoBTS - Feature #3075: do not transmit SI13 when the PCU is not connectedhttps://projects.osmocom.org/issues/3075?journal_id=100182018-06-23T18:51:04Zlaforge
<ul><li><strong>Assignee</strong> set to <i>stsp</i></li></ul> OsmoBTS - Feature #3075: do not transmit SI13 when the PCU is not connectedhttps://projects.osmocom.org/issues/3075?journal_id=103922018-07-20T13:56:01Zstsp
<ul></ul><p>neels wrote:</p>
<blockquote>
<p>Do not send SI13 when the PCU is not connected</p>
</blockquote>
<p>As far as I understand, rsl_rx_bcch_info() attempts to tell the PCU to send SI13,<br />which will always fail as long as the PCU socket is disconnected.<br />Once the PCU comes up, pcu_rx_txt_ind() will immediately ask the PCU to send SI13.</p>
<p>laforge wrote:</p>
<blockquote>
<p>Even more important than not sending SI13 is to not send the indication that SI13 <br />is present (In SI3 or SI4, AFAIR).</p>
</blockquote>
<p>This indication is present in SI3 (see gsm_generate_si() in osmo-bsc/system_information.c).</p>
<p>However, the code which generates SI3 lives in osmo-bsc, based on the gprs type of the BTS.<br />There doesn't seem to be a way to monitor the PCU socket status from osmo-bsc, Is that possible somehow?<br />Or should the BTS be modifying the SI3 which was provided by the BSC?</p> OsmoBTS - Feature #3075: do not transmit SI13 when the PCU is not connectedhttps://projects.osmocom.org/issues/3075?journal_id=103932018-07-20T13:56:43Zstsp
<ul><li><strong>Status</strong> changed from <i>New</i> to <i>In Progress</i></li></ul> OsmoBTS - Feature #3075: do not transmit SI13 when the PCU is not connectedhttps://projects.osmocom.org/issues/3075?journal_id=103942018-07-20T14:47:20Zneelsnhofmeyr@sysmocom.de
<ul></ul><p>Ok I see, depending on 'gprs mode (none|gprs|egprs)', osmo-bsc composes an SI3 to indicate GPRS service.<br />So the situation is about a failing GPRS service, where osmo-bsc expects the PCU to work, but it crashed/is broken/unreachable.<br />My personal intuition would be that osmo-bts masks the SI3 to indicate no GPRS as long as the PCU isn't connected.</p>
<p>But I'm not sure if that's a good idea semantically, it's a bit of a layering violation.<br />Maybe some custom non-standard message could tell the BSC that the PCU is down and osmo-bsc masks the SI3 instead?<br />Patching over SI3 in osmo-bts is certainly the easiest.</p>
<p>...not sure...</p>
<p>On the need to fix: at first I thought it's not critically important, but when in practice a GPRS service breaks down, it would potentially also take down voice with it, because all the phones would start to constantly LU at different cells, trying to catch a working PCU, which would load the network and could disrupt service. So I think in terms of infrastructure stability it's pretty bad to indicate GPRS presence if the BTS knows that the PCU is down.</p> OsmoBTS - Feature #3075: do not transmit SI13 when the PCU is not connectedhttps://projects.osmocom.org/issues/3075?journal_id=104832018-07-26T15:05:58Zstsp
<ul></ul><p>I don't think coupling this behaviour to osmo-bsc would be wise.<br />What if osmo-bts runs with a BSC from another vendor?</p>
<p>This patch makes the BTS override the GPRS indicator in SI3: <a class="external" href="https://gerrit.osmocom.org/#/c/osmo-bts/+/10170">https://gerrit.osmocom.org/#/c/osmo-bts/+/10170</a><br />Parsing SI3 rest octets is a bit ugly but I don't see a better solution.</p> OsmoBTS - Feature #3075: do not transmit SI13 when the PCU is not connectedhttps://projects.osmocom.org/issues/3075?journal_id=104952018-07-27T10:49:01Zstsp
<ul></ul><p>To make the proposed patch nice we'll need to port some code from osmo-bsc to libosmocore first.</p>
<p>This is step one of that porting process: <a class="external" href="https://gerrit.osmocom.org/c/libosmocore/+/10185">https://gerrit.osmocom.org/c/libosmocore/+/10185</a></p> OsmoBTS - Feature #3075: do not transmit SI13 when the PCU is not connectedhttps://projects.osmocom.org/issues/3075?journal_id=104972018-07-27T13:09:47Zneelsnhofmeyr@sysmocom.de
<ul></ul><p>just noticing, there's also a GPRS presence indicator in the rest octets in SI4</p> OsmoBTS - Feature #3075: do not transmit SI13 when the PCU is not connectedhttps://projects.osmocom.org/issues/3075?journal_id=104992018-07-27T14:25:10Zstsp
<ul></ul><p>This patch ports rest-octet encoding from osmo-bsc to libosmocore: <a class="external" href="https://gerrit.osmocom.org/#/c/libosmocore/+/10189">https://gerrit.osmocom.org/#/c/libosmocore/+/10189</a></p> OsmoBTS - Feature #3075: do not transmit SI13 when the PCU is not connectedhttps://projects.osmocom.org/issues/3075?journal_id=106262018-08-07T10:11:19Zstsp
<ul></ul><p>This issue is currently waiting for confirmation from several authors to allow us to re-licence their code from AGPL to GPLv2+.</p> OsmoBTS - Feature #3075: do not transmit SI13 when the PCU is not connectedhttps://projects.osmocom.org/issues/3075?journal_id=121002018-10-09T06:43:21Zstsp
<ul></ul><p>This issue is still waiting for a response from Jolly to our question about the license change.</p> OsmoBTS - Feature #3075: do not transmit SI13 when the PCU is not connectedhttps://projects.osmocom.org/issues/3075?journal_id=126352018-11-20T09:11:02Zstsp
<ul></ul><p>We haven't received a written statement by Jolly yet. Still waiting.</p> OsmoBTS - Feature #3075: do not transmit SI13 when the PCU is not connectedhttps://projects.osmocom.org/issues/3075?journal_id=130062018-12-30T12:28:56Zstsp
<ul></ul><p>Got permission from Jolly :)</p> OsmoBTS - Feature #3075: do not transmit SI13 when the PCU is not connectedhttps://projects.osmocom.org/issues/3075?journal_id=133512019-02-14T11:11:46Zlaforge
<ul></ul> OsmoBTS - Feature #3075: do not transmit SI13 when the PCU is not connectedhttps://projects.osmocom.org/issues/3075?journal_id=143322019-05-08T18:10:24Zlaforge
<ul><li><strong>Status</strong> changed from <i>In Progress</i> to <i>Stalled</i></li><li><strong>Assignee</strong> changed from <i>stsp</i> to <i>4368</i></li><li><strong>% Done</strong> changed from <i>0</i> to <i>20</i></li></ul> OsmoBTS - Feature #3075: do not transmit SI13 when the PCU is not connectedhttps://projects.osmocom.org/issues/3075?journal_id=146402019-05-28T22:36:56Zlaforge
<ul><li><strong>Status</strong> changed from <i>Stalled</i> to <i>In Progress</i></li><li><strong>Assignee</strong> changed from <i>4368</i> to <i>laforge</i></li><li><strong>% Done</strong> changed from <i>20</i> to <i>80</i></li></ul><p>A new, updated patch has been submitted as <a class="external" href="https://gerrit.osmocom.org/#/c/osmo-bts/+/10170/">https://gerrit.osmocom.org/#/c/osmo-bts/+/10170/</a> and tested using newly-developed TTCN-3 tests from <a class="external" href="https://gerrit.osmocom.org/#/c/osmo-ttcn3-hacks/+/14215/">https://gerrit.osmocom.org/#/c/osmo-ttcn3-hacks/+/14215/</a></p> OsmoBTS - Feature #3075: do not transmit SI13 when the PCU is not connectedhttps://projects.osmocom.org/issues/3075?journal_id=146432019-05-29T14:10:58Zlaforge
<ul><li><strong>Status</strong> changed from <i>In Progress</i> to <i>Resolved</i></li><li><strong>% Done</strong> changed from <i>80</i> to <i>100</i></li></ul><p>both patch and test have been merged.</p> OsmoBTS - Feature #3075: do not transmit SI13 when the PCU is not connectedhttps://projects.osmocom.org/issues/3075?journal_id=146472019-05-29T14:19:47Zlaforge
<ul><li><strong>Related to</strong> <i><a class="issue tracker-1 status-3 priority-2 priority-default closed" href="/issues/4032">Bug #4032</a>: RLL/LAPDm ABM has no TTCN3 tests</i> added</li></ul> OsmoBTS - Feature #3075: do not transmit SI13 when the PCU is not connectedhttps://projects.osmocom.org/issues/3075?journal_id=178832020-03-29T13:18:53Zfixeria
<ul><li><strong>Status</strong> changed from <i>Resolved</i> to <i>New</i></li><li><strong>% Done</strong> changed from <i>100</i> to <i>80</i></li></ul><p>I just noticed that <strong>System Information Type 4</strong> still contains GPRS Indicator while osmo-pcu is not connected. Also, <strong>System Information Type 13</strong> is still being transmitted by osmo-bts-trx (is it expected?). <strong>System Information Type 3</strong> contains no GPRS Indicator as expected.</p>
<blockquote>
<p>Updated by neels over 1 year ago<br />just noticing, there's also a GPRS presence indicator in the rest octets in SI4</p>
</blockquote> OsmoBTS - Feature #3075: do not transmit SI13 when the PCU is not connectedhttps://projects.osmocom.org/issues/3075?journal_id=181482020-05-04T18:26:50Zfixeria
<ul><li><strong>% Done</strong> changed from <i>80</i> to <i>90</i></li></ul><p>I've extended the existing TTCN-3 test cases to check GPRS Indicator in SI4 Rest Octets too, see:</p>
<p><a class="external" href="https://gerrit.osmocom.org/c/osmo-ttcn3-hacks/+/18027">https://gerrit.osmocom.org/c/osmo-ttcn3-hacks/+/18027</a> BTS: manually compose Rest Octets for SI Type 3 and 4<br /><a class="external" href="https://gerrit.osmocom.org/c/osmo-ttcn3-hacks/+/18028">https://gerrit.osmocom.org/c/osmo-ttcn3-hacks/+/18028</a> BTS: fix missing GPRS Indicator in SI4 Rest Octets<br /><a class="external" href="https://gerrit.osmocom.org/c/osmo-ttcn3-hacks/+/18029">https://gerrit.osmocom.org/c/osmo-ttcn3-hacks/+/18029</a> BTS: refactor f_get_si3(), so it can be used to get SI4<br /><a class="external" href="https://gerrit.osmocom.org/c/osmo-ttcn3-hacks/+/18030">https://gerrit.osmocom.org/c/osmo-ttcn3-hacks/+/18030</a> BTS: verify presence of GPRS Indicator in SI4 Rest Octets</p> OsmoBTS - Feature #3075: do not transmit SI13 when the PCU is not connectedhttps://projects.osmocom.org/issues/3075?journal_id=181492020-05-04T18:45:42Zfixeria
<ul><li><strong>File</strong> <a href="/attachments/4101">si3_rest_octets.pcapng.gz</a> <a class="icon-only icon-download" title="Download" href="/attachments/download/4101/si3_rest_octets.pcapng.gz">si3_rest_octets.pcapng.gz</a> added</li></ul><p>I also noticed that osmo-bts changes unrelated "3G Early Classmark Sending Restriction" field in SI3 Rest Octets:</p>
<pre>
SI 3 Rest Octets
L... .... = Selection Parameters: Not Present
.L.. .... = Optional Power Offset: Not Present
..L. .... = SYSTEM INFORMATION TYPE 2ter: Not available
...L .... = Early Classmark Sending: Not Allowed
.... L... = Scheduling if and where: Not Present
.... .H.. = GPRS Indicator: Present
GPRS Indicator
.... ..00 0... .... = GPRS RA Colour: 0
.0.. .... = SI13 Position: SYSTEM INFORMATION TYPE 13 message is sent on BCCH Norm (0)
..L. .... = 3G Early Classmark Sending Restriction: Neither UTRAN, CDMA2000 nor GERAN IU MODE CLASSMARK CHANGE message shall be sent with the Early classmark sending
...L .... = SI2quater Indicator: Not Present
.... L... = SI21 Indicator: Not Present
Padding Bits: default padding
</pre>
<p>vs</p>
<pre>
SI 3 Rest Octets
L... .... = Selection Parameters: Not Present
.L.. .... = Optional Power Offset: Not Present
..L. .... = SYSTEM INFORMATION TYPE 2ter: Not available
...L .... = Early Classmark Sending: Not Allowed
.... L... = Scheduling if and where: Not Present
.... .L.. = GPRS Indicator: Not Present
.... ..H. = 3G Early Classmark Sending Restriction: The sending of UTRAN,CDMA2000 and GERAN IU MODE CLASSMARK CHANGE messages are controlled by the Early Classmark Sending Control parameter
.... ...L = SI2quater Indicator: Not Present
0... .... = SI13alt Position: If Iu mode is supported in the cell, SYSTEM INFORMATION TYPE 13alt message is sent on BCCH Norm
.L.. .... = SI21 Indicator: Not Present
Padding Bits: default padding
</pre> OsmoBTS - Feature #3075: do not transmit SI13 when the PCU is not connectedhttps://projects.osmocom.org/issues/3075?journal_id=181522020-05-04T19:05:18Zfixeria
<ul></ul><blockquote>
<p>I also noticed that osmo-bts changes unrelated "3G Early Classmark Sending Restriction" field in SI3 Rest Octets:</p>
</blockquote>
<p><a class="external" href="https://gerrit.osmocom.org/c/libosmocore/+/18036">https://gerrit.osmocom.org/c/libosmocore/+/18036</a> rest_octets: fix encoding of 3G Early Classmark Sending Restriction</p> OsmoBTS - Feature #3075: do not transmit SI13 when the PCU is not connectedhttps://projects.osmocom.org/issues/3075?journal_id=198762020-10-11T19:20:40Zlaforge
<ul></ul><ul>
<li><a class="external" href="https://gerrit.osmocom.org/c/libosmocore/+/20541">https://gerrit.osmocom.org/c/libosmocore/+/20541</a></li>
<li><a class="external" href="https://gerrit.osmocom.org/c/osmo-bts/+/20542">https://gerrit.osmocom.org/c/osmo-bts/+/20542</a></li>
<li><a class="external" href="https://gerrit.osmocom.org/c/osmo-bts/+/20542">https://gerrit.osmocom.org/c/osmo-bts/+/20542</a></li>
</ul> OsmoBTS - Feature #3075: do not transmit SI13 when the PCU is not connectedhttps://projects.osmocom.org/issues/3075?journal_id=211412021-02-06T11:14:56Zlaforge
<ul><li><strong>Status</strong> changed from <i>New</i> to <i>Resolved</i></li><li><strong>% Done</strong> changed from <i>90</i> to <i>100</i></li></ul><p>all patches merged</p>