Adding priority for EMLPP service in paging type 1

[Snehasish Kar]

Snehasish Kar has shared a OneDrive file with you. To view it, click the link below.


<https://1drv.ms/u/s!Ar2IfAyw5vH1gQwV5RARUfsedW9g>
[https://r1.res.office365.com/owa/prem/images/dc-generic_20.png]<https://1drv.ms/u/s!Ar2IfAyw5vH1gQwV5RARUfsedW9g>

emlpp_test 1.pcapng<https://1drv.ms/u/s!Ar2IfAyw5vH1gQwV5RARUfsedW9g>



Hello Harald

I have been able to add priority to the paging and setup command, though it is hard-coded  now, but still please check it and let me know if I am correct or wrong.

diff --git a/openbsc/src/libbsc/abis_rsl.c b/openbsc/src/libbsc/abis_rsl.c
index 5a508b207..5b45cd497 100644
--- a/openbsc/src/libbsc/abis_rsl.c
+++ b/openbsc/src/libbsc/abis_rsl.c
@@ -1034,6 +1034,8 @@ int rsl_paging_cmd(struct gsm_bts *bts, uint8_t paging_group, uint8_t len,
        if (bts->type == GSM_BTS_TYPE_RBS2000 && is_gprs)
                msgb_tv_put(msg, RSL_IE_ERIC_PACKET_PAG_IND, 0);

+       msgb_tv_put(msg, RSL_IE_EMLPP_PRIO, 0x7f);
+
        msg->dst = bts->c0->rsl_link;

diff --git a/openbsc/src/libmsc/gsm_04_08.c b/openbsc/src/libmsc/gsm_04_08.c
index 09e35cce2..a7ba85744 100644
--- a/openbsc/src/libmsc/gsm_04_08.c
+++ b/openbsc/src/libmsc/gsm_04_08.c
@@ -2376,7 +2376,7 @@ static int gsm48_cc_tx_setup(struct gsm_trans *trans, void *arg)
        /* signal */
        if (setup->fields & MNCC_F_SIGNAL)
                gsm48_encode_signal(msg, setup->signal);
-
+       msgb_v_put(msg,GSM48_IE_PRIORITY_LEV | 0xf);
        new_cc_state(trans, GSM_CSTATE_CALL_PRESENT);

        rate_ctr_inc(&trans->net->msc_ctrs->ctr[MSC_CTR_CALL_MT_SETUP]);


diff --git a/src/common/paging.c b/src/common/paging.c
index aa604e7..092da05 100644
--- a/src/common/paging.c
+++ b/src/common/paging.c
@@ -293,7 +293,7 @@ static int fill_paging_type_1(uint8_t *out_buf, const uint8_t *identity1_lv,
                cur = tlv_put(cur, GSM48_IE_MOBILE_ID, identity2_lv[0], identity2_lv+1);

        pt1->l2_plen = L2_PLEN(cur - out_buf);
-
+       cur = v_put(cur,/*priority*/0x7f);
        return cur - out_buf;
 }


I have attached the wireshark traces please check. Also there is a wireshark dump with airprobe to see whether the paging messages are correctly being transported or not.

BR
Snehasish



________________________________
From: Harald Welte <laforge at gnumonks.org>
Sent: Thursday, December 27, 2018 2:28 AM
To: Snehasish Kar
Cc: openbsc at lists.osmocom.org
Subject: Re: Adding priority for EMLPP service in paging type 1

Hi Snehasish,

On Wed, Dec 26, 2018 at 02:13:38PM +0000, Snehasish Kar wrote:
> Please find the updated patches:

Thanks, there were no requested related pcap traces, though.

I think you are making the wrong assumption that you can simply add a byte
to the RSL message which then magically appears on the Um interface.  Instead,
you need to study how eMLPP is actually implemented over Abis. There's an additional
information element that needs to be added to the RSL PAGING COMMAND, see Section
8.5.5 of 3GPP TS 48.058.  The IE is of type TV, so you need to msgb_put_tv(...)
to add it.

Furthermore, you will need to teach OsmoBTS (assuming you are using OsmoBTS) to
interpret that additional IE and then construct the air interface paging rest
octets from it.

Please also notice that openbsc.git is no longer maintained anymore and it is
strongly suggested you switch to the new "split NITB" architecture consisting of
osmo-bsc.git + osmo-msc.git + osmo-hlr.git.

We're very much looking forward to receiving your patches contributing eMLPP
support to the Osmocom stack.

Regards,
        Harald

--
- Harald Welte <laforge at gnumonks.org>           http://laforge.gnumonks.org/
============================================================================
"Privacy in residential applications is a desirable marketing option."
                                                  (ETSI EN 300 175-7 Ch. A6)
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.osmocom.org/pipermail/openbsc/attachments/20181231/3bccb234/attachment.htm>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: airprobe.pcapng
Type: application/x-pcapng
Size: 4792548 bytes
Desc: airprobe.pcapng
URL: <http://lists.osmocom.org/pipermail/openbsc/attachments/20181231/3bccb234/attachment.bin>