https://projects.osmocom.org/https://projects.osmocom.org/favicon.ico?16647414092016-10-15T21:34:03ZOpen Source Mobile CommunicationsOpenBSC - Feature #1824: don't try to deactivate the SACCH in case of deactivation of PDCH channelshttps://projects.osmocom.org/issues/1824?journal_id=22552016-10-15T21:34:03Zlaforge
<ul><li><strong>File</strong> <a href="/attachments/2412">rsl_chan_act_pdch.pcap</a> <a class="icon-only icon-download" title="Download" href="/attachments/download/2412/rsl_chan_act_pdch.pcap">rsl_chan_act_pdch.pcap</a> added</li></ul><p>attaching pcap file with example.</p>
<p>don't be surprised if wireshark doesn't fully decode the messages. The non-standard RSL extensions require a patch (see my commit 89c71c635f0e85a66de3a176b0a0df2970d8058b in wireshark.git on osmocom.org, branch laforge/om2000-201610). However, a full decode of the RSL CHAN ACT message is not required to solve this bug.</p> OpenBSC - Feature #1824: don't try to deactivate the SACCH in case of deactivation of PDCH channelshttps://projects.osmocom.org/issues/1824?journal_id=22592016-10-16T22:38:48Zneelsnhofmeyr@sysmocom.de
<ul></ul><p>With my default wireshark I basically see only "malformed packet", so I guess I'd need the extensions.</p>
<p>I'm not familiar with SACCH, but if you say that SACCH only exists for CS channels, then the<br />obvious answer is that we can't deact SACCH on a PDCH channel.</p>
<p>The conclusion would be that rsl_rx_conn_fail() calling rsl_rf_chan_release_err() in abis_rsl.c<br />must not pass SACCH_DEACTIVATE unconditionally. This patch could be all that's needed:</p>
<pre>
diff --git a/openbsc/src/libbsc/abis_rsl.c b/openbsc/src/libbsc/abis_rsl.c
index b9132a5..eb33b3a 100644
--- a/openbsc/src/libbsc/abis_rsl.c
+++ b/openbsc/src/libbsc/abis_rsl.c
@@ -859,7 +859,9 @@ static int rsl_rf_chan_release_err(struct gsm_lchan *lchan)
{
if (lchan->state != LCHAN_S_ACTIVE)
return 0;
- return rsl_rf_chan_release(lchan, 1, SACCH_DEACTIVATE);
+ return rsl_rf_chan_release(lchan, 1,
+ ts_is_pdch(lchan->ts) ?
+ SACCH_NONE : SACCH_DEACTIVATE);
}
</pre>
<p>(haven't tested nor compiled it yet)</p>
<p>BTW...</p>
<p>From 08.58 8.4.4:<br /><pre>
CONNECTION FAILURE INDICATION
This message is sent from BTS to BSC to indicate that an active connection has been broken for some reason.
</pre></p>
<p>That sounds like a channel was already fully established and then fails.<br />From a failure to switch on a PDCH lchan, I would expect an 'Channel Activation Nack' instead?<br />Anyway, if the RBS2000 replies with a conn failure, we have to be able to deal with it...</p> OpenBSC - Feature #1824: don't try to deactivate the SACCH in case of deactivation of PDCH channelshttps://projects.osmocom.org/issues/1824?journal_id=31522017-02-28T13:58:54Zdexter
<ul><li><strong>Status</strong> changed from <i>New</i> to <i>Resolved</i></li></ul> OpenBSC - Feature #1824: don't try to deactivate the SACCH in case of deactivation of PDCH channelshttps://projects.osmocom.org/issues/1824?journal_id=31742017-02-28T17:32:44Zlaforge
<ul><li><strong>Status</strong> changed from <i>Resolved</i> to <i>Closed</i></li></ul>