Cellular Network Infrastructure » Radio Access Network » OsmoBSC

Should be possible rather simply, IMHO. Just use NM_MT_IPACC_GET_NVATTR
rather than NM_MT_IPACC_SET_NVATTR and request
NM_ATT_IPACC_PRIM_OML_CFG_LIST ?

Attaching a pcap file that can be used as an example/template. It was
taken back in 2009 when we were fist playing with nanoBTss.

ipaccess-telnet could also be used to get the current OML_IP

echo "db::getprimaryomlipaddr" | ipaccess-telnet 192.168.200.150 3210 | perl -nle 'print "$1" if (/Primary OML IP Address: ([\d.]*)/)'

With attached file I can request the OML IP Addr against a nanoBTS using "ipaccess-config -O 192.168.30.100".

It answers correctly the OML IP of my BSC:

<0004> /home/pespin/dev/sysmocom/git/osmo-bsc/src/osmo-bsc/abis_nm.c:544 OC=BASEBAND-TRANSCEIVER(04) INST=(00,00,ff): Get Attributes Response for BTS0
<0004> /home/pespin/dev/sysmocom/git/osmo-bsc/src/osmo-bsc/abis_nm.c:555 (bts=0,trx=0) Get Attributes Response: OML IP is 192.168.30.1:0
<0004> /home/pespin/dev/sysmocom/git/osmo-bsc/src/osmo-bsc/abis_nm.c:563 OC=BASEBAND-TRANSCEIVER(04) INST=(00,00,ff): BTS0: Get Attr Response without Response Info?!

It seems however that getting attributes from nanoBTS (aka !osmo-bts type) is not supported, I had to patch following code in src/osmo-bsc/abis_nm.c:

@@ -1649,10 +1663,12 @@ int abis_nm_get_attr(struct gsm_bts *bts, uint8_t obj_class, uint8_t bts_nr, uin
        if (bts->type != GSM_BTS_TYPE_OSMOBTS) {
                LOGPC(DNM, LOGL_NOTICE, "Getting attributes from BTS%d type %s is not supported.\n",
                      bts->nr, btstype2str(bts->type));
-               return -EINVAL;
+               //return -EINVAL;
        }

Then, function abis_nm_rx_get_attr_resp receiving the Get Attribute Response message doesn't support nanoBTS, because instead it looks for some information which nanoBTS doesn't provide in the response (while osmo-bts probably does).

I now need to find the way to send the received OML IP addr up to the stack so ipaccess-config can print it. Probably we want to pass the content of TLVP_VAL(&tp, NM_ATT_IPACC_PRIM_OML_CFG_LIST);

With follow up patch I can read the Unit_ID too (to show case how to request several attributes at once).

<0004> /home/pespin/dev/sysmocom/git/osmo-bsc/src/osmo-bsc/abis_nm.c:558 (bts=0,trx=0) Get Attributes Response: OML IP is 192.168.30.1:0 UNIT_ID=666/0/0

So Basically OML IP is a TV of 4 bytes IP and 2 bytes port, and UNIT_ID is a TLV where L=len of string including EOS character (which is also in the buffer of course).

It seems only requested NM_ATT_IPACC_PRIM_OML_CFG attr is enveloped in NM_ATT_IPACC_PRIM_OML_CFG_LIST when getting the response from the nanoBTS. Other attributes, such as NM_ATT_IPACC_UNIT_ID or NM_ATT_IPACC_SEC_OML_CFG, come directly and not under that OML_CFG_LIST attr.

I attach a pcap example with Get Attr and Get Attr response for NM_ATT_IPACC_PRIM_OML_CFG and NM_ATT_IPACC_UNIT_ID.

I fixed a bug still present in wireshark master which prevented from decoding NM_ATT_IPACC_PRIM_OML_CFG_LIST and as a result the whole message:
https://code.wireshark.org/review/30532 gsm_abis_oml: Support decoding IPA Primary OML Config List

It seems there's another bug in master wireshark which shows IP in incorrect format (ntohl/htnol required). I'll submit another patch for that one.

Here you can find the patch decoding the OML Primary IP Addr correctly:
https://code.wireshark.org/review/30533 gsm_abis_oml: Decode Primary OML IP Address as big endian

I started reworking some code in abis_nm_rx_get_attr_resp and I can now parse OML Primary IP ad Unit ID in there.

I first thought nanoBTS didn't support the "SW Configuration" and "Get ARI" ones and that's why we blocked sending Get Attributes for nanobts, but it actually supports it. I attach a pcap file showing the req and response. I need to rework a bit my code after seeing this.

Next step will be to add a signal in abis_nm_rx_get_attr_resp or abis_nm_rcvmsg_fom which sends content of the foh or similar, and then in ipaccess-config I can parse it and add code to print json format or similar which I can then use in osmo-gsm-tester.

I submitted a patch set containing several fixes and imrovements in osmo-bsc abis_nm.c, and some code in ipaccess-config to add a -G parameter which can be used by osmo-gsm-tester to get OML IP and Unit_ID:
https://gerrit.osmocom.org/#/c/osmo-bsc/+/11686/

Draft patch to use this feature to speed up osmo-gsm-tester tests:
https://gerrit.osmocom.org/#/c/osmo-gsm-tester/+/11750 nanobts: Use -G parameter of ipaccess-config to avoid need to restart nanoBTS

Merged. closing.