UE keep connect and disconnect

[pchat-imm]

I have followed this tutorial srsRAN gNB with COTS UEs. It seems that my UE can connect to network, but it keep being released all the time. So my UE cannot use internet.

My system

• Ubuntu 22.04 to run open5gs by ./build/test/apps/5gc which run config from sample.yml.txt
• B210 as RAN, which run under performance mode and run with sudo ./gnb -c gnb_config.yaml with config gnb_config.txt
• Quectel RM510 as UE
• the amf address is 127.0.0.2

The gNB can connect to the Core and receive IP address, as shown in gnb_trace.txt

$ sudo ./gnb -c gnb_fllay.yml 

The PRACH detector will not meet the performance requirements with the configuration {Format B4, ZCZ 0, SCS 30kHz, Rx ports 1}.
Lower PHY in quad executor mode.

--== srsRAN gNB (commit 2f90c8b60) ==--

Connecting to AMF on 127.0.0.2:38412
Available radio types: uhd.
[INFO] [UHD] linux; GNU C++ version 10.5.0; Boost_107400; UHD_4.0.0.HEAD-0-g90ce6062
[INFO] [LOGGING] Fastpath logging disabled at runtime.
Making USRP object with args 'type=b200,num_recv_frames=64,num_send_frames=64'
[INFO] [B200] Detected Device: B210
[INFO] [B200] Operating over USB 3.
[INFO] [B200] Initialize CODEC control...
[INFO] [B200] Initialize Radio control...
[INFO] [B200] Performing register loopback test... 
[INFO] [B200] Register loopback test passed
[INFO] [B200] Performing register loopback test... 
[INFO] [B200] Register loopback test passed
[INFO] [B200] Setting master clock rate selection to 'automatic'.
[INFO] [B200] Asking for clock rate 16.000000 MHz... 
[INFO] [B200] Actually got clock rate 16.000000 MHz.
[INFO] [MULTI_USRP] Setting master clock rate selection to 'manual'.
[INFO] [B200] Asking for clock rate 23.040000 MHz... 
[INFO] [B200] Actually got clock rate 23.040000 MHz.
Cell pci=1, bw=20 MHz, dl_arfcn=627340 (n78), dl_freq=3410.1 MHz, dl_ssb_arfcn=626976, ul_freq=3410.1 MHz

==== gNodeB started ===

However, when I try to connect UE to the system, it gets registered and released repeatedly, as shown on log of open5gs 5gc.log

04/24 11:34:06.125: [amf] INFO: InitialUEMessage (../src/amf/ngap-handler.c:401)
04/24 11:34:06.125: [amf] INFO: [Added] Number of gNB-UEs is now 1 (../src/amf/context.c:2656)
04/24 11:34:06.125: [amf] INFO:     RAN_UE_NGAP_ID[0] AMF_UE_NGAP_ID[1] TAC[7] CellID[0x66c000] (../src/amf/ngap-handler.c:562)
04/24 11:34:06.125: [amf] INFO: Unknown UE by 5G-S_TMSI[AMF_ID:0x20040,M_TMSI:0xc00005e2] (../src/amf/context.c:1858)
04/24 11:34:06.125: [amf] INFO: [Added] Number of AMF-UEs is now 1 (../src/amf/context.c:1621)
04/24 11:34:06.125: [gmm] INFO: Registration request (../src/amf/gmm-sm.c:1224)
04/24 11:34:06.125: [gmm] INFO: [Unknown ID]    5G-S_GUTI[AMF_ID:0x20040,M_TMSI:0xc00005e2] (../src/amf/gmm-handler.c:185)
04/24 11:34:06.145: [gmm] INFO: Identity response (../src/amf/gmm-sm.c:1492)
04/24 11:34:06.145: [gmm] INFO: [suci-0-001-01-0-0-0-0000062714]    SUCI (../src/amf/gmm-handler.c:944)
04/24 11:34:06.432: [gmm] INFO: [imsi-001010000062714] Registration complete (../src/amf/gmm-sm.c:2323)
04/24 11:34:06.432: [amf] INFO: [imsi-001010000062714] Configuration update command (../src/amf/nas-path.c:591)
04/24 11:34:06.432: [gmm] INFO:     UTC [2024-04-24T04:34:06] Timezone[0]/DST[0] (../src/amf/gmm-build.c:558)
04/24 11:34:06.432: [gmm] INFO:     LOCAL [2024-04-24T11:34:06] Timezone[25200]/DST[0] (../src/amf/gmm-build.c:563)
04/24 11:34:09.262: [amf] INFO: UE Context Release [Action:2] (../src/amf/ngap-handler.c:1696)
04/24 11:34:09.262: [amf] INFO:     RAN_UE_NGAP_ID[0] AMF_UE_NGAP_ID[1] (../src/amf/ngap-handler.c:1697)
04/24 11:34:09.262: [amf] INFO:     SUCI[suci-0-001-01-0-0-0-0000062714] (../src/amf/ngap-handler.c:1701)
04/24 11:34:09.262: [amf] INFO: [Removed] Number of gNB-UEs is now 0 (../src/amf/context.c:2663)

With unstable connection, the UE cannot access internet although it can connect to the network as shown on quectel minicom quectel_minicom.txt

at+cops?                                                                     
+COPS: 0,0,"Open5GS Magic",11    

Also the wireshark of gnb only return mac but ngap files return blank gNB_wireshark.zip

I have tried

1. make sure to Enable IPv4/IPv6 Forwarding and add NAT rule

$ sudo sysctl -w net.ipv4.ip_forward=1
$ sudo sysctl -w net.ipv6.conf.all.forwarding=1

### Add NAT Rule
$ sudo iptables -t nat -A POSTROUTING -s 10.45.0.0/16 ! -o ogstun -j MASQUERADE
$ sudo ip6tables -t nat -A POSTROUTING -s 2001:db8:cafe::/48 ! -o ogstun -j MASQUERADE

2. config sim as 90170 with pySim-prog.py. I used to use 00101 which is not successful as well.
3. disable service 124 and 125 with pySim-shell.py with script

verify_adm XXXXX
# Key Provisioning
select MF
select ADF.USIM 
select DF.5GS 
select EF.SUCI_Calc_Info 
update_binary_decoded '{ "prot_scheme_id_list": [ {"priority": 0, "identifier": 2, "key_index": 1}, {"priority": 1, "identifier": 1, "key_index": 2}, {"priority": 2, "identifier": 0, "key_index": 0}], "hnet_pubkey_list": [ {"hnet_pubkey_identifier": 27, "hnet_pubkey": "0272DA71976234CE833A6907425867B82E074D44EF907DFB4B3E21C1C2256EBCD1"}, {"hnet_pubkey_identifier": 30, "hnet_pubkey": "5A8D38864820197C3394B92613B20B91633CBD897119273BF8E4A6F4EEC0A650"}]}'

# Routing Indicator
select MF
select ADF.USIM 
select DF.5GS 
select EF.Routing_Indicator
update_binary 0071ffff

# Service Table
select MF
select ADF.USIM 
select EF.UST 
ust_service_deactivate 124
ust_service_deactivate 125

4. change ue from Huawei CPE to Quectel
5. with Quectel, I follow this paper and set it to use IPv4, make it roaming, make it connect to APN internet which i specify on localhost:9999

AT+QMBNCFG=“select”,“ROW Commercial”
2) AT+QNWPREFCFG=“nr5g band”
3) AT+QNWPREFCFG=“mode pref”
4) AT+QNWPREFCFG=“mode pref”, nr5g
5) AT+QNWPREFCFG=“nr5g disable mode”,0
6) AT+CGDCONT=1,“IP”,“internet”,“0.0.0.0”,0,0
AT+QNWPREFCFG="roaming_pref",255

I have attached
config files
gnb_config.txt
sample.yml.txt
quectel_minicom.txt

log gnb
[gnb_trace.txt](http
gNB_wireshark.zip
s://github.com/srsran/srsRAN_Project/files/15161510/gnb_trace.txt)
log open5gs
5gc.log

[pgawlowicz]

Could you provide gnb logs?

[pchat-imm]

my gnb log turns out blank gnb.log

[pgawlowicz]

Change log level to debug.

[pchat-imm]

debug_gnb.zip

[pchat-imm]

@pgawlowicz I change to another UE. The UE can connect to the network consistently without being released, with a stable RNTI of 4601.However, the UE still cannot access the internet.

I used spectrum analyzer to capture at center freq 3410 MHz. It shows spectrums. It peaks at 3416 MHz with amplitude -17.67 dBm.

Could you please suggest what should I try more? Thank you very much.

today's log (the code is done with the same config of this discussion)
I am sorry that the gNB log is quite hugh. So i post it on google drive. So please download it.

• gnb https://drive.google.com/file/d/17YaRBFZdKfkGMpkAmmgp_HU_ZqzT2Wy7/view?usp=drive_link
• gnb_wireshark (only MAC is presented, NGAP does not contains anything) gnb_wireshark.zip
• open5gs 5gc.log

[pgawlowicz]

Can the UE ping core network?

Did you enable IP forwarding and add the NAT rule? see here: https://open5gs.org/open5gs/docs/tutorial/01-your-first-lte/

[pchat-imm]

Thank you for reminding the NAT rule again. It turns out that my UE (ZLTX21 WIFI 5 CPE) need to be toggled on the NAT rule again before the UE can access the internet. I use iphone 13 connected to WiFi from this CPE and can test speedtest, IPerf properly.

Thank you very much for your help! @pgawlowicz 🙏🙏🙏

[pengnist]

I also experience RRC release with srsue. But it only happens a few mins after connection is established and no application is launched, such as iperf or ping. Is this expected?

[HaoxinSEU]

Maybe you can set the inactivity_timer under cu_cp to 7200, so that the UE doesn't disconnect in a short time.

[pengnist]

@HaoxinSEU Problem solved. Thanks!

[pchat-imm]

@HaoxinSEU This one is helping a lot! It gives me time to config my UE properly.