https://osmocom.org/https://osmocom.org/favicon.ico?16647414092018-09-12T16:41:09ZOpen Source Mobile CommunicationsOsmoBSC - Bug #3548: COMPLETE LAYER 3 INFORMATION does not contain Codec List (BSS Supported) information elementhttps://osmocom.org/issues/3548?journal_id=113172018-09-12T16:41:09Zdexter
<ul><li><strong>File</strong> <a href="/attachments/3337">trace_from_a_normal_mo_call_with_osmo-bsc_and_osmo-msc.pcapng</a> <a class="icon-only icon-download" title="Download" href="/attachments/download/3337/trace_from_a_normal_mo_call_with_osmo-bsc_and_osmo-msc.pcapng">trace_from_a_normal_mo_call_with_osmo-bsc_and_osmo-msc.pcapng</a> added</li></ul><p>Attached one finds a trace from a MO call with osmo-bsc and osmo-msc.</p>
<p>From what I unterstand the IE Codec List (BSS Supported) is all about what the BSS supports. So there we would send what codecs/rates the BTS which currently handles the call can support. In 3GPP TS 48.008 3.1.1.1 one can read:</p>
<p>"The MSC is the entity that carries out the necessary analysis on the call control information received from the MS or<br />fixed network customer. If an IP based user plane interface is supported, the Codec List (BSS supported) shall be taken<br />into account, considering the Codec capabilities of the core network, aiming for true end-to-end Codec negotiation and<br />for common supported Codec(s)."</p>
<p>Also when I look at the trace, the codecs that the MS supports become known way later with the SETUP. The CM SERVICE REQUEST carries a Mobile Station Classmark 2, but that one is only about basic capabilities like encryption PS capability etc, but not codecs.</p>
<p>So I think what we need to do is to lookup what codecs are configured for the BTS in particular VTY (VTY-Setting) and package that info into a Codec List.</p> OsmoBSC - Bug #3548: COMPLETE LAYER 3 INFORMATION does not contain Codec List (BSS Supported) information elementhttps://osmocom.org/issues/3548?journal_id=113272018-09-13T07:48:02Zlaforge
<ul></ul><p>On Wed, Sep 12, 2018 at 04:41:09PM +0000, dexter [REDMINE] wrote:</p>
<blockquote>
<p>So I think what we need to do is to lookup what codecs are configured for the BTS in particular VTY (VTY-Setting) and package that info into a Codec List.</p>
</blockquote>
well, to be more precise, what we need to support is the intersection of
<ul>
<li>BTS hardware/firmware capabilities (nanoBTS doesn't do HRv1, BS11 doesn't do AMR, ...)</li>
<li>BSC VTY/config file policy for BTS (if any)</li>
<li>BSC VTY/config file policy for BSC/"msc" (if any)</li>
</ul> OsmoBSC - Bug #3548: COMPLETE LAYER 3 INFORMATION does not contain Codec List (BSS Supported) information elementhttps://osmocom.org/issues/3548?journal_id=113502018-09-14T18:25:30Zdexter
<ul><li><strong>Status</strong> changed from <i>New</i> to <i>In Progress</i></li><li><strong>% Done</strong> changed from <i>0</i> to <i>50</i></li></ul><p>Codec List (BSS Supported) is now included in COMPLETE LAYER 3 INFORMATION. Unfortunately I still have problems getting the configuration for AMR (S0-S15) right. While the unit-tests work there is still something wrong in the real world. I keep getting 0x0000 as configuration for AMR. All other codecs that do not have S0-S15 look good so far.</p>
<p>The following related patches are now in review:</p>
<p><a class="external" href="https://gerrit.osmocom.org/#/c/libosmocore/+/10961">https://gerrit.osmocom.org/#/c/libosmocore/+/10961</a> gsm0808: add function to convert amr gsm0408 setings to gsm0808<br /><a class="external" href="https://gerrit.osmocom.org/#/c/osmo-bsc/+/10963">https://gerrit.osmocom.org/#/c/osmo-bsc/+/10963</a> codec_pref: add AMR configuration bits to make_scl_config in unit-test<br /><a class="external" href="https://gerrit.osmocom.org/#/c/osmo-bsc/+/10964">https://gerrit.osmocom.org/#/c/osmo-bsc/+/10964</a> codec_pref: fix missing breaks in switch-case statement<br /><a class="external" href="https://gerrit.osmocom.org/#/c/osmo-bsc/+/10965">https://gerrit.osmocom.org/#/c/osmo-bsc/+/10965</a> codec_pref: Add Codec List to COMPLETE LAYER 3 INFORMATION</p>
<p>I also added a TTCN3 test that at least checks if the Codec List (BSS Supported) is present in COMPLETE LAYER 3 INFORMATION</p>
<p><a class="external" href="https://gerrit.osmocom.org/#/c/osmo-ttcn3-hacks/+/10966">https://gerrit.osmocom.org/#/c/osmo-ttcn3-hacks/+/10966</a> MSC_ConnectionHandler: Make sure COMPLETE LAYER 3 INFORMATION contains a ...</p> OsmoBSC - Bug #3548: COMPLETE LAYER 3 INFORMATION does not contain Codec List (BSS Supported) information elementhttps://osmocom.org/issues/3548?journal_id=115472018-09-21T12:04:25Zneelsnhofmeyr@sysmocom.de
<ul></ul><p>Just a side note, you mentioned that you would rather not include this IE for SCCPlite, but 48.008 3.2.1.32 says:</p>
<pre>
NOTE 4: Codec List (BSS Supported) shall be included, if the radio access network
supports an IP based user plane interface.
</pre>
<p>We use osmo-mgw == an IP based user plane interface for both AoIP and SCCPlite, so this is mandatory for all our A-interface implementations.<br />So add this IE for SCCPlite as well, please.</p> OsmoBSC - Bug #3548: COMPLETE LAYER 3 INFORMATION does not contain Codec List (BSS Supported) information elementhttps://osmocom.org/issues/3548?journal_id=115552018-09-21T12:30:06Zlaforge
<ul></ul><p>On Fri, Sep 21, 2018 at 12:04:25PM +0000, neels [REDMINE] wrote:</p>
<blockquote>
<p>We use osmo-mgw == an IP based user plane interface for both AoIP and SCCPlite, so this is mandatory for all our A-interface implementations.<br />So add this IE for SCCPlite as well, please.</p>
</blockquote>
<p>sorry, but absolutely not!</p>
<p><strong>either</strong> there is an BSSAP/SCCP interface using circuit identity codes adhering to the specs<br />before AoIP was introduced, <strong>or</strong> it is an AoIP interface.</p>
<p>So for SCCPlite, everything must look exactly like in legacy E1/TDM based networks.</p> OsmoBSC - Bug #3548: COMPLETE LAYER 3 INFORMATION does not contain Codec List (BSS Supported) information elementhttps://osmocom.org/issues/3548?journal_id=115592018-09-21T15:47:42Zdexter
<ul><li><strong>% Done</strong> changed from <i>50</i> to <i>80</i></li></ul><p>I think we now have a good speech codec list in the COMPLETE LAYER 3 INFORMATION message. The test look good so far, but I get build failures on jenkins which I do not understand yet.</p>
<p>See also:</p>
<p><a class="external" href="https://gerrit.osmocom.org/#/c/osmo-bsc/+/11058">https://gerrit.osmocom.org/#/c/osmo-bsc/+/11058</a> gsm_data.c: Set reasonable AMR codec defaults in gsm_bts_alloc()<br /><a class="external" href="https://gerrit.osmocom.org/#/c/osmo-bsc/+/11059">https://gerrit.osmocom.org/#/c/osmo-bsc/+/11059</a> assignment_fsm: only include speech codec (choosen) on AoIP networks<br /><a class="external" href="https://gerrit.osmocom.org/#/c/osmo-bsc/+/10965">https://gerrit.osmocom.org/#/c/osmo-bsc/+/10965</a> codec_pref: Add Codec List to COMPLETE LAYER 3 INFORMATION [WIP]</p> OsmoBSC - Bug #3548: COMPLETE LAYER 3 INFORMATION does not contain Codec List (BSS Supported) information elementhttps://osmocom.org/issues/3548?journal_id=115632018-09-23T14:09:30Zneelsnhofmeyr@sysmocom.de
<ul></ul><p>laforge wrote:</p>
<blockquote>
<p>On Fri, Sep 21, 2018 at 12:04:25PM +0000, neels [REDMINE] wrote:</p>
<blockquote>
<p>We use osmo-mgw == an IP based user plane interface for both AoIP and SCCPlite, so this is mandatory for all our A-interface implementations.<br />So add this IE for SCCPlite as well, please.</p>
</blockquote>
<p>sorry, but absolutely not!</p>
<p><strong>either</strong> there is an BSSAP/SCCP interface using circuit identity codes adhering to the specs<br />before AoIP was introduced, <strong>or</strong> it is an AoIP interface.</p>
</blockquote>
<p>Wait, what? To me it looks like our user plane is definitely going over IP?<br />Maybe we should talk about that in person some time to clarify...</p> OsmoBSC - Bug #3548: COMPLETE LAYER 3 INFORMATION does not contain Codec List (BSS Supported) information elementhttps://osmocom.org/issues/3548?journal_id=115642018-09-23T15:20:28Zlaforge
<ul></ul><p>On Sun, Sep 23, 2018 at 02:09:30PM +0000, neels [REDMINE] wrote:</p>
<blockquote><blockquote>
<p><strong>either</strong> there is an BSSAP/SCCP interface using circuit identity codes adhering to the specs<br />before AoIP was introduced, <strong>or</strong> it is an AoIP interface.</p>
</blockquote>
<p>Wait, what? To me it looks like our user plane is definitely going over IP?</p>
</blockquote>
<p>This is a way too literal and narrow look on the subject matter.</p>
<p>Put yourself into the position of the 3GPP spec author when you update a specification<br />that so far only supported E1/T1/TDM based transmission and you now add AoIP support to it.</p>
<p>If you then phrase something like "an IP based user plane interface", then you are referring<br />to AoIP. Even more so, you are referring to the specific use case where AoIP is used for signaling,<br /><strong>and</strong> also an IP/RTP bearer is negotiated in AoIP signaling. Remember, even in AoIP signaling,<br />you can still negotiate a TDM-based bearer using CIC!</p>
<p>The person updating the 3GPP spec clearly is not thinking about some proprietary, vendor-specific,<br />nowhere-specified hack that some people at some point have put together at ip.access, Altobridge<br />and others to transport the classic A interface over an IP bearer - because to him that doesn't<br />exist, as it wasn't part of 3GPP specs.</p> OsmoBSC - Bug #3548: COMPLETE LAYER 3 INFORMATION does not contain Codec List (BSS Supported) information elementhttps://osmocom.org/issues/3548?journal_id=115692018-09-24T09:50:22Zdexter
<ul><li><strong>% Done</strong> changed from <i>80</i> to <i>90</i></li></ul><p>The build problem is now fixed. The problem was that osmo-bsc couln't re-read the config once it was written. The reason for this was that the config only allows a set of up to four rates (active set). I had selected more. We now have a reasonable default of four codecs and the python tests are fine again. I also removed the WIP flag for 10965.</p> OsmoBSC - Bug #3548: COMPLETE LAYER 3 INFORMATION does not contain Codec List (BSS Supported) information elementhttps://osmocom.org/issues/3548?journal_id=118112018-10-01T07:50:50Zdexter
<ul><li><strong>Status</strong> changed from <i>In Progress</i> to <i>Resolved</i></li><li><strong>% Done</strong> changed from <i>90</i> to <i>100</i></li></ul><p>The related patch made it into master. Osmo-bsc now includes the speech codec list in the assignment complete message when the network is an AoIP network. When sccp-lite is in use the IE is omitted.</p>