OpenBSC October 2012

openbsc@lists.osmocom.org

30 participants
36 discussions

Analysing the communication between the BSC and the MSC in a sysmoBTS
by Yann R. Moupinda 09 Oct '12

09 Oct '12

Hello everyone, thanks for the ideas you gave me about how i can learn more about the communication between BSC and MSC in my sysmoBTS. Since last week i've been looking at the source codes and it's still difficult for me to follow the exchanged messages betwenn BSC and MSC. I don't have high programming skills. Instead of using sysmoBTS as an autonomous self-contained GSM network (NITB mode), i'd like to configure it in the BSC-only mode running the osmo-bts and osmo-bsc. I read that i will need a MSC that can provide an A-over-IP interface using SCCP-lite. I saw that the "on-waves/bsc-master" branch is implementing such a SCCP and works have been done to create a GSM0808 like API and move the MSC code inside OpenBSC over to use this API. So i was wondering how far this project has been developed yet. Do you already have any interesting results that can help me? If not, it can be also interesting for me to know how you did your tests by implementing the bsc-only mode (osmo-bsc)? Did you connect it to a real MSC or did you have anything else emulating the MSC/HLR/VLR/EIR functions? Best regards Yann

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Oct 3, 8pm / Osmocom Berlin User Group meeting?
by Nico Golde 09 Oct '12

09 Oct '12

Hi all! I *think* Harald is pretty busy and also unlikely to attend prospective meeting tomorrow. Also there is bank holiday tomorrow in Germany and at least I personally will use that to stay away from technology for a bit, so I won't come. Nevertheless, I thought I'd write this email to remind people that in theory there is a meeting tomorrow and discuss if other people attend. I personally would propose to shift the meeting to next week (for purely selfish reasons ;). As far as I know, there is no formal presentation tomorrow. Anyway, will anyone attend tomorrow or is everyone in favor of shifting a week? In case it takes place, for the people who did not attend so far, the usual snippet from Harald's mails: Oct 3, 8pm @ CCC Berlin, Marienstr. 11, 10113 Berlin If you are interested to show up, feel free to do so. There is no registration required. The meeting is free as in "free beer", despite no actual free beer being around. Cheers Nico

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Erlang command line interface (OTP-version) available
by M. Josenhans 08 Oct '12

08 Oct '12

Hello, the Erlang command line interface (OTP version) is available on Github: https://github.com/josemic/Erlang-command-line-interface_otp This is a telnet commandline server written in Erlang using OTP libraries. It provides features such as command-completion, command-abbreviation, command-help, reading/writing commands from/to file and modular command-registration. Its behaviour is kept similar to the well known, C-written, OpenBSC telnet command line server. It is intended for future inclusion into Osmocom's Erlang projects. The installation instructions are found in the github wiki. Cheers, Michael

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[PATCH] bsc_init: Forget which SIs are valid for the trx.
by Holger Hans Peter Freyther 08 Oct '12

08 Oct '12

The recent commit to improve the SI generation lead to setting the BCCH SIs for all TRX in a multi-trx setup. This is because we create the SIs globally but si_valid appears to be limited to the 'current' trx. Warn if we attempt to set SIs for the BCCH on a trx that does not have a BCCH. --- openbsc/src/libbsc/bsc_init.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/openbsc/src/libbsc/bsc_init.c b/openbsc/src/libbsc/bsc_init.c index e05aec7..7a60e04 100644 --- a/openbsc/src/libbsc/bsc_init.c +++ b/openbsc/src/libbsc/bsc_init.c @@ -129,6 +129,11 @@ static int rsl_si(struct gsm_bts_trx *trx, enum osmo_sysinfo_type i, int si_len) GSM_BTS_SI(bts, i), si_len); break; default: + if (bts->c0 != trx) + LOGP(DRR, LOGL_ERROR, + "Attempting to set BCCH SI%s on wrong BTS/TRX (%d/%d)\n", + get_value_string(osmo_sitype_strs, i), + bts->nr, trx->nr); rc = rsl_bcch_info(trx, osmo_sitype2rsl(i), GSM_BTS_SI(bts, i), si_len); break; @@ -149,6 +154,9 @@ static int set_system_infos(struct gsm_bts_trx *trx) ms_pwr_ctl_lvl(bts->band, bts->ms_max_power); bts->si_common.cell_sel_par.neci = bts->network->neci; + /* Zero, forget the state of the SIs */ + bts->si_valid = 0; + /* First, we determine which of the SI messages we actually need */ if (trx == bts->c0) { -- 1.7.10.4

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Analysing the communication between the BSC and the MSC in a sysmoBTS
by Yann R. Moupinda 04 Oct '12

04 Oct '12

Hello everybody First of all, let me introduce myself. My name is Yann Moupinda and I'm a student doing his Master thesis in the field of GSM technology. For my thesis, the company for which i'm working now, bought a sysmoBTS from sysmocom. The sysmoBTS is configured as a stand alone GSM network in a box (NITB) running the osmo-nitb and the osmo-bts programs. An important part of my thesis is to understand how the sysmoBTS works and therefore I did some measurements with wireshark to analyse the data flow between the BTS,BSC and MSC/HLR/VLR/EIR. This is also to see the main differences between a sysmoBTS and a conventional GSM Network. I used the " tcpdump " - command on the loopback interface lo0 to capture the data flow between the GSM components and then, the analysis with wireshark shows me only the data flow between BTS and BSC. It's possible to see such messages like LOCATION UPDATING REQUEST and IDENTITY REQUEST wich are normally, transparently exchanged between Mobile Station (MS) and the Network subsystem (MSC/HLR/VLR/EIR). All these messages are always addressed to, or from the same BSC TCP-port 3003. So i can not see what happens behind this port (behind BSC). In order to get the communication between BSC and MSC, i decided to have a deeper look on the logging messages of the sysmoBTS. Even there, i cannot recognize how the data transmission between BSC and MSC works. Does anyone know how to get this information? Any guidance would be appreciated. I have included one .pcap file and a text file of the logging messages taken while i powered on the mobile phone. Best regards, Yann.

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OpenBSC and 3G
by John Otten 02 Oct '12

02 Oct '12

Hello Everyone, I now have OpenBSC (including GPRS) up and running with a fair amount of stability, using an IP.Access 2G BTS. Now I am looking towards the next stage - getting a 3G system operating. I have the use of an IP.Access NodeB that I would like get running with OpenBSC. In performing my due diligence, I found Harald's 3G road map from December 2010 or so. I am wondering what the current state of development is. I see that IP.Access' URSL protocol was an issue back then, because it is proprietary. Has anyone managed to get far enough in their development that they have implemented the protocol? I also see from Dieter Spaar's blog that he is making some progress, but he states his code is not ready for public release. Since I don't see much about 3G on the OpenBSC wiki, I am assuming that no one has any code that they would want to share at this point. I imagine I may have to forge ahead on my own. I am fairly new to GSM development, and I haven't really delved into the OpenBSC source yet (other than to discern what might have caused some problems I encountered), so if anyone has any suggestions on where to begin, or has some issues where I might be able to assist in order to move development further down the road, please let me know. Thanks! John

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OpenBSC October 2012