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4315 discussions

LAPD sequence error issues while bootstrapping RBS2308
by Pablo Neira Ayuso 21 Mar '12

21 Mar '12

Hi Andreas, I'm having some problems while bootstrapping RBS2308 with the existing code. I think it is related to LAPD sequence number checkings: lapd.c:595 TX: 02 01 02 00 0c 11 01 80 1e 02 27 17 59 06 0 00 00 00 00 00 00 00 00 00 00 00 00 ff e5 04 00 dahdi.c:248 dahdi TX (TS=1): 37 bytes lapd_core.c:1832 msg-len 31 sent 31 left 0 N201 260 t byte 0c lapd.c:345 RX: 02 01 01 04 lapd_core.c:1256 RR received in state LAPD_STATE_MF_EST lapd_core.c:739 ack frame 1 lapd_core.c:216 stop T200 lapd_core.c:208 start T203 lapd_core.c:1780 lapd_send_i() called from line 1294 lapd.c:345 RX: 00 01 02 04 10 1c 1a 02 62 11 1c 11 01 80 lapd_core.c:1463 I received in state LAPD_STATE_MF_EST lapd_core.c:1512 N(S) sequence error: N(S)=1, V(R)=0 ^^^^^^^^^^^^^^ It seems to me that the BSC transmits data while something is still coming from the BTS. Then, BSC's LAPD code silently drops the message (without rejection). Just a bit later the BSC gets a rejection from BTS's RSL layer. lapd.c:595 TX: 00 01 09 00 dahdi.c:248 dahdi TX (TS=1): 6 bytes lapd_core.c:224 stop T203 lapd_core.c:208 start T203 lapd_core.c:1780 lapd_send_i() called from line 1538 lapd.c:345 RX: 00 01 00 04 10 1c 1a 02 62 11 1c 11 01 80 lapd_core.c:1463 I received in state LAPD_STATE_MF_EST lapd_core.c:1546 incrementing V(R) to 1 lapd_core.c:224 stop T203 lapd_core.c:208 start T203 lapd_core.c:1555 message in single I frame abis_rsl.c:1128 (bts=0,trx=0) ERROR REPORT CAUSE=0x62(Message Sequence Error) So the bootstrapping process never ends and the BTS never comes up. Let me know if you can provide any clue to resolve this issue. Thanks!

2 1

"Osmo-USRP": combining OpenBTS and Osmocom
by Thomas Cooper 20 Mar '12

20 Mar '12

Hey all, I've been working on connecting OpenBTS and osmo-bts ever since Harald formed the openbts-osmo repo (http://cgit.osmocom.org/cgit/openbts-osmo) and left me with a nice muxer framework and L1-L2 separation. I've named it Osmo-USRP but you can call it openbts-osmo or TrueBTS or whatever; it's not a big deal. Unfortunately I'm running short on time for completing my MS research, so testing is nowhere near complete but I figured I'd let the public users help me out a bit here if they want to try it out. Many thanks to Tom Tsou for helping me weed out bugs and test too. I've only scratched the surface of testing it with USRP1, USRP2, single vs. multiple PCs (Ubuntu and Fedora), and multiple BTSs. I've been able to get a stable network of 1 and 2 BTSs across 2 PCs with multiple MSs camped, and voice calls and SMS working. There seem to be a few fickle and unknown issues depending on which PC/Linux flavors/time of day I tested, and of course sometimes it will work for a certain MS but not another. Sometimes MSs won't location update to the network, or will hit errors when establishing a call; in the usual case, this won't even free the TCH so if resources run out the BTS must be rebooted. Just a few issues to name here, and I'm sure there are more out there. The current focus of work (when I can find time) is implementing handover between cells. I'm not even sure if osmo-bts and OpenBTS contain all the supporting functionality for handover (OpenBSC does though). The MSs correctly send SACCH meas reports, the BSC detects and decides to handover, and the TCH is activated, but I think the Handover Command is getting lost in the BTS or the MS Handover Accept bursts are being processed. The newly activated osmo-bts instance segfaults somewhere in LAPDm. I haven't had time lately to pinpoint the error, but just wanted to update on the current status of that. Also, multiple configuration files are needed because I have network parameters hard-coded (just for ease), which is elaborated some in the wiki. I ran into a segfault/bug trying to implement passing in config parameters from OpenBSC, and gave up to pursue more critical aspects of the project. Github repo: https://github.com/tacooper (first release tag for Osmo-USRP = v0.1) README/Guide: https://github.com/tacooper/Osmo-USRP/downloads (issues, configuration, and example setup for single/multi-BTS networks) If you'd like to help out by testing or even working on this project, it is much appreciated, even if only to help me grow my understanding of GSM networks through discussion. Thanks! Tom Cooper

3 4

[PATCH 9/9] Fixed problem of mute audio on some calls
by Andreas Eversberg 16 Mar '12

16 Mar '12

When reading from RTP socket, the first read() may fail right after connecting to remote socket. Subsequent read() will work as it should. If the remote socket does not open fast enough, the transmitted RTP payload can cause an ICMP (connection refused) packet reply. This causes the read to fail with errno=111. In all other error cases, the errno is logged at debug level. In all error cases, reading is not disabled. --- openbsc/src/libtrau/rtp_proxy.c | 13 ++++++++++--- 1 file changed, 10 insertions(+), 3 deletions(-) diff --git a/openbsc/src/libtrau/rtp_proxy.c b/openbsc/src/libtrau/rtp_proxy.c index 88753b6..23d0d1d 100644 --- a/openbsc/src/libtrau/rtp_proxy.c +++ b/openbsc/src/libtrau/rtp_proxy.c @@ -503,9 +503,16 @@ static int rtp_socket_read(struct rtp_socket *rs, struct rtp_sub_socket *rss) return -ENOMEM; rc = read(rss->bfd.fd, msg->data, RTP_ALLOC_SIZE); - if (rc <= 0) { - rss->bfd.when &= ~BSC_FD_READ; - return rc; + if (rc == 0) + goto out_free; + if (rc < 0) { + /* Ignore "connection refused". this happens, If we open the + * socket faster than the remove side. */ + if (errno == ECONNREFUSED) + goto out_free; + DEBUGPC(DLMUX, "Read of RTP socket (%p) failed (errno %d, " + "%s)\n", rs, errno, strerror(errno)); + goto out_free; } msgb_put(msg, rc); -- 1.8.1.5 --------------060407040809040206020102--

1 0

[PATCH 9/9] Fixed problem of mute audio on some calls
by Andreas Eversberg 16 Mar '12

16 Mar '12

When reading from RTP socket, the first read() may fail right after connecting to remote socket. Subsequent read() will work as it should. If the remote socket does not open fast enough, the transmitted RTP payload can cause an ICMP (connection refused) packet reply. This causes the read to fail with errno=111. In all other error cases, the errno is logged at debug level. In all error cases, reading is not disabled. --- openbsc/src/libtrau/rtp_proxy.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) diff --git a/openbsc/src/libtrau/rtp_proxy.c b/openbsc/src/libtrau/rtp_proxy.c index 88753b6..bb158e8 100644 --- a/openbsc/src/libtrau/rtp_proxy.c +++ b/openbsc/src/libtrau/rtp_proxy.c @@ -503,9 +503,16 @@ static int rtp_socket_read(struct rtp_socket *rs, struct rtp_sub_socket *rss) return -ENOMEM; rc = read(rss->bfd.fd, msg->data, RTP_ALLOC_SIZE); + if (rc == 0) + goto out_free; if (rc <= 0) { - rss->bfd.when &= ~BSC_FD_READ; - return rc; + /* Ignore "connection refused". this happens, If we open the + * socket faster than the remove side. */ + if (errno == 111) + return 0; + DEBUGPC(DLMUX, "Read of RTP socket (%p) failed (errno %d)\n", + rs, errno); + goto out_free; } msgb_put(msg, rc); -- 1.8.1.5 --------------050303020108080701030307--

1 0

Unknown payload type on OpenBSC when using rtp-bridge on LCR
by Nik Pakar 15 Mar '12

15 Mar '12

Hi Andreas, After some extensive testing i have done using jolly/rtpmux branch to get rtp to go directly between bsc and softswitch (yate in this case) i came across following scenario. MO call goes to OpenBSC/LCR then to yate routed back to OpenBSC/LCR and MT. Signalling seems all fine including codec negotiating as through out the path AMR/96 is been negotiated well. But once call connected, no rtp stream exist and i see following error on OpenBSC. received RTP frame with unknown payload type 98 Full topology and logs/trace from openbsc, LCR and yate is on this attachment. What could be the reason for bsc to get payload type 98. http://pastebin.com/rPfMamx0 Rgds Nik

3 2

Compiling LCR for OpenBSC
by Nik Pakar 15 Mar '12

15 Mar '12

Do I have to have mISDN for LCR even im not going to use any isdn interface ? Im trying to connect the NITB to LCR and LCR to asterisk all on ip. Thanks for any help. Rgds Nik

8 29

study on openbsc
by Kwan 13 Mar '12

13 Mar '12

Hello, I am a student from Hong Kong and I take a project about openbsc. I have a BTS that product from interWave. I contacted interWave engineer and he said he can borrow us the E1 card to connect BTS. But I don't know how to make openbsc to support this BTS. I can provide some detail about this BTS if you need. Thank, Kwan

2 3

nanoBTS behind NAT
by Nik Pakar 09 Mar '12

09 Mar '12

Dear all, will the openbsc setup works with nanoBTSs sitting behind a NAT ? Rgds Nik

5 10

[PATCH] Add support for AMR frames to MNCC/RTP interface
by Andreas Eversberg 08 Mar '12

08 Mar '12

AMR rate is currently fixed to 5.9k. --- openbsc/src/libmsc/gsm_04_08.c | 1 + openbsc/src/libtrau/rtp_proxy.c | 53 ++++++++++++++++++++++++++++++++++++----- 2 files changed, 48 insertions(+), 6 deletions(-) diff --git a/openbsc/src/libmsc/gsm_04_08.c b/openbsc/src/libmsc/gsm_04_08.c index df93433..a0650ab 100644 --- a/openbsc/src/libmsc/gsm_04_08.c +++ b/openbsc/src/libmsc/gsm_04_08.c @@ -2953,6 +2953,7 @@ int mncc_tx_to_cc(struct gsm_network *net, int msg_type, void *arg) case GSM_TCHF_FRAME: case GSM_TCHF_FRAME_EFR: case GSM_TCHH_FRAME: + case GSM_TCH_FRAME_AMR: /* Find callref */ trans = trans_find_by_callref(net, data->callref); if (!trans) { diff --git a/openbsc/src/libtrau/rtp_proxy.c b/openbsc/src/libtrau/rtp_proxy.c index 143bfa0..95729ef 100644 --- a/openbsc/src/libtrau/rtp_proxy.c +++ b/openbsc/src/libtrau/rtp_proxy.c @@ -192,21 +192,41 @@ static int rtp_decode(struct msgb *msg, uint32_t callref, struct msgb **data) return -EINVAL; } break; + case RTP_PT_AMR: + break; default: DEBUGPC(DLMUX, "received RTP frame with unknown payload " "type %d\n", rtph->payload_type); return -EINVAL; } - new_msg = msgb_alloc(sizeof(struct gsm_data_frame) + payload_len, - "GSM-DATA"); + if (payload_len > 33) { + DEBUGPC(DLMUX, "RTP payload too large (%d octets)\n", + payload_len); + return -EINVAL; + } + + if (rtph->payload_type == RTP_PT_AMR) { + new_msg = msgb_alloc(sizeof(struct gsm_data_frame) + 1 + + payload_len, "GSM-DATA (AMR)"); + } else { + new_msg = msgb_alloc(sizeof(struct gsm_data_frame) + + payload_len, "GSM-DATA"); + } if (!new_msg) return -ENOMEM; frame = (struct gsm_data_frame *)(new_msg->data); frame->msg_type = msg_type; frame->callref = callref; - memcpy(frame->data, payload, payload_len); - msgb_put(new_msg, sizeof(struct gsm_data_frame) + payload_len); + if (rtph->payload_type == RTP_PT_AMR) { + frame->data[0] = payload_len; + msgb_put(new_msg, sizeof(struct gsm_data_frame) + 1 + + payload_len); + memcpy(frame->data + 1, payload, payload_len); + } else { + msgb_put(new_msg, sizeof(struct gsm_data_frame) + payload_len); + memcpy(frame->data, payload, payload_len); + } *data = new_msg; return 0; @@ -264,6 +284,11 @@ int rtp_send_frame(struct rtp_socket *rs, struct gsm_data_frame *frame) payload_len = RTP_LEN_GSM_HALF; duration = RTP_GSM_DURATION; break; + case GSM_TCH_FRAME_AMR: + payload_type = RTP_PT_AMR; + payload_len = frame->data[0]; + duration = RTP_GSM_DURATION; + break; default: DEBUGPC(DLMUX, "unsupported message type %d\n", frame->msg_type); @@ -291,7 +316,18 @@ int rtp_send_frame(struct rtp_socket *rs, struct gsm_data_frame *frame) } } - msg = msgb_alloc(sizeof(struct rtp_hdr) + payload_len, "RTP-GSM-FULL"); + if (payload_len > 33) { + DEBUGPC(DLMUX, "RTP payload too large (%d octets)\n", + payload_len); + return -EINVAL; + } + + if (frame->msg_type == GSM_TCH_FRAME_AMR) + msg = msgb_alloc(sizeof(struct rtp_hdr) + payload_len, + "RTP-GSM (AMR)"); + else + msg = msgb_alloc(sizeof(struct rtp_hdr) + payload_len, + "RTP-GSM"); if (!msg) return -ENOMEM; rtph = (struct rtp_hdr *)msg->data; @@ -305,7 +341,12 @@ int rtp_send_frame(struct rtp_socket *rs, struct gsm_data_frame *frame) rtph->timestamp = htonl(rs->transmit.timestamp); rs->transmit.timestamp += duration; rtph->ssrc = htonl(rs->transmit.ssrc); - memcpy(msg->data + sizeof(struct rtp_hdr), frame->data, payload_len); + if (frame->msg_type == GSM_TCH_FRAME_AMR) + memcpy(msg->data + sizeof(struct rtp_hdr), frame->data + 1, + payload_len); + else + memcpy(msg->data + sizeof(struct rtp_hdr), frame->data, + payload_len); msgb_put(msg, sizeof(struct rtp_hdr) + payload_len); msgb_enqueue(&rss->tx_queue, msg); rss->bfd.when |= BSC_FD_WRITE; -- 1.8.1.5 --------------040208000603050009060705--

1 0

[PATCH] Add support for AMR frames to MNCC/RTP interface
by Andreas Eversberg 08 Mar '12

08 Mar '12

AMR rate is currently fixed to 5.9k. --- openbsc/src/libmsc/gsm_04_08.c | 1 + openbsc/src/libtrau/rtp_proxy.c | 35 ++++++++++++++++++++++++++++++----- 2 files changed, 31 insertions(+), 5 deletions(-) diff --git a/openbsc/src/libmsc/gsm_04_08.c b/openbsc/src/libmsc/gsm_04_08.c index df93433..a0650ab 100644 --- a/openbsc/src/libmsc/gsm_04_08.c +++ b/openbsc/src/libmsc/gsm_04_08.c @@ -2953,6 +2953,7 @@ int mncc_tx_to_cc(struct gsm_network *net, int msg_type, void *arg) case GSM_TCHF_FRAME: case GSM_TCHF_FRAME_EFR: case GSM_TCHH_FRAME: + case GSM_TCH_FRAME_AMR: /* Find callref */ trans = trans_find_by_callref(net, data->callref); if (!trans) { diff --git a/openbsc/src/libtrau/rtp_proxy.c b/openbsc/src/libtrau/rtp_proxy.c index 143bfa0..913d64d 100644 --- a/openbsc/src/libtrau/rtp_proxy.c +++ b/openbsc/src/libtrau/rtp_proxy.c @@ -192,21 +192,35 @@ static int rtp_decode(struct msgb *msg, uint32_t callref, struct msgb **data) return -EINVAL; } break; + case RTP_PT_AMR: + break; default: DEBUGPC(DLMUX, "received RTP frame with unknown payload " "type %d\n", rtph->payload_type); return -EINVAL; } - new_msg = msgb_alloc(sizeof(struct gsm_data_frame) + payload_len, - "GSM-DATA"); + if (rtph->payload_type == RTP_PT_AMR) { + new_msg = msgb_alloc(sizeof(struct gsm_data_frame) + 1 + + payload_len, "GSM-DATA"); + } else { + new_msg = msgb_alloc(sizeof(struct gsm_data_frame) + + payload_len, "GSM-DATA"); + } if (!new_msg) return -ENOMEM; frame = (struct gsm_data_frame *)(new_msg->data); frame->msg_type = msg_type; frame->callref = callref; - memcpy(frame->data, payload, payload_len); - msgb_put(new_msg, sizeof(struct gsm_data_frame) + payload_len); + if (rtph->payload_type == RTP_PT_AMR) { + frame->data[0] = payload_len; + msgb_put(new_msg, sizeof(struct gsm_data_frame) + 1 + + payload_len); + memcpy(frame->data + 1, payload, payload_len); + } else { + msgb_put(new_msg, sizeof(struct gsm_data_frame) + payload_len); + memcpy(frame->data, payload, payload_len); + } *data = new_msg; return 0; @@ -264,6 +278,11 @@ int rtp_send_frame(struct rtp_socket *rs, struct gsm_data_frame *frame) payload_len = RTP_LEN_GSM_HALF; duration = RTP_GSM_DURATION; break; + case GSM_TCH_FRAME_AMR: + payload_type = RTP_PT_AMR; + payload_len = frame->data[0]; + duration = RTP_GSM_DURATION; + break; default: DEBUGPC(DLMUX, "unsupported message type %d\n", frame->msg_type); @@ -305,7 +324,13 @@ int rtp_send_frame(struct rtp_socket *rs, struct gsm_data_frame *frame) rtph->timestamp = htonl(rs->transmit.timestamp); rs->transmit.timestamp += duration; rtph->ssrc = htonl(rs->transmit.ssrc); - memcpy(msg->data + sizeof(struct rtp_hdr), frame->data, payload_len); + if (frame->msg_type == GSM_TCH_FRAME_AMR) { + memcpy(msg->data + sizeof(struct rtp_hdr), frame->data + 1, + payload_len); + } else { + memcpy(msg->data + sizeof(struct rtp_hdr), frame->data, + payload_len); + } msgb_put(msg, sizeof(struct rtp_hdr) + payload_len); msgb_enqueue(&rss->tx_queue, msg); rss->bfd.when |= BSC_FD_WRITE; -- 1.8.3.2 --------------090303090405010206070901--

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