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Open5GS 5GC & srsRAN 5G with ZeroMQ UE / RAN Sample Configuration

srsRAN_Project and srsRAN_4G software suites include a virtual radio which uses the ZeroMQ networking library to transfer radio samples between applications. Therefore, in order to use U-Plane's DN (Data Network) as a trial, I built a simulation environment for the 5GC mobile network. This briefly describes the overall and configuration files in the Virtualbox VM environment.

Sample Configurations and Miscellaneous for Mobile Network

<a id="toc"></a>

Table of Contents

<a id="overview"></a>

Overview of Open5GS 5GC Simulation Mobile Network

I created a 5GC mobile network (Internet reachable) for simulation with the aim of creating an environment in which packets can be sent end-to-end with one DN for one DNN.

The following minimum configuration was set as a condition.

The built simulation environment is as follows.

<img src="./images/network-overview.png" title="./images/network-overview.png" width=1000px></img>

The 5GC / UE / RAN used are as follows.

Each VMs are as follows.

VMSW & RoleIP addressOSCPU <br> (Min)Memory <br> (Min)HDD <br> (Min)
VM1Open5GS 5GC C-Plane192.168.0.111/24Ubuntu 22.0412GB20GB
VM2Open5GS 5GC U-Plane192.168.0.112/24Ubuntu 22.0411GB20GB
VM3srsRAN Project ZMQ RAN<br>(gNodeB)192.168.0.121/24Ubuntu 22.0424GB10GB
VM4srsRAN 4G ZMQ UE<br>(NR-UE)192.168.0.122/24Ubuntu 22.0412GB10GB

AMF & SMF addresses are as follows.

NFIP addressIP address on SBISupported S-NSSAI
AMF192.168.0.111127.0.0.5SST:1, SD:0x000001
SMF192.168.0.111127.0.0.4SST:1, SD:0x000001

Subscriber Information (other information is the same) is as follows.

UEIMSIDNNOP/OPcS-NSSAI
UE (NR-UE)001010000000000internetOPcSST:1, SD:0x000001

I registered these information with the Open5GS WebUI. In addition, 3GPP TS 35.208 "4.3 Test Sets" is published by 3GPP as test data for the 3GPP authentication and key generation functions (MILENAGE).

DN is as follows.

DNS-NSSAITUNnel interface of DNDNNTUNnel interface of UE
10.45.0.0/16SST:1 <br> SD:0x000001ogstuninternettun_srsue

The main information of gNodeB is as follows.

MCCMNCTACgNodeB ID
0010110x19b

Additional information.

Open5GS 5GC U-Plane worked fine on Raspberry Pi 4 Model B. I used Ubuntu 20.04 (64bit) for Raspberry Pi 4 as the OS. I think it would be convenient to place a compact U-Plane in the edge environment and use it as an end-point for DN.

In addition, I have not confirmed the communication performance.

<a id="changes"></a>

Changes in configuration files of Open5GS 5GC and srsRAN 5G ZMQ UE / RAN

Please refer to the following for building Open5GS and srsRAN 5G ZMQ UE / RAN respectively.

<a id="changes_cp"></a>

Changes in configuration files of Open5GS 5GC C-Plane

The following parameters can be used in the logic that selects UPF as the connection destination by PFCP.

For the sake of simplicity, I used only DNN this time.

<a id="changes_cp"></a>

Changes in configuration files of Open5GS 5GC C-Plane

--- amf.yaml.orig       2024-03-24 15:36:48.000000000 +0900
+++ amf.yaml    2024-03-29 22:14:08.359119294 +0900
@@ -19,29 +19,30 @@
         - uri: http://127.0.0.200:7777
   ngap:
     server:
-      - address: 127.0.0.5
+      - address: 192.168.0.111
   metrics:
     server:
       - address: 127.0.0.5
         port: 9090
   guami:
     - plmn_id:
-        mcc: 999
-        mnc: 70
+        mcc: 001
+        mnc: 01
       amf_id:
         region: 2
         set: 1
   tai:
     - plmn_id:
-        mcc: 999
-        mnc: 70
+        mcc: 001
+        mnc: 01
       tac: 1
   plmn_support:
     - plmn_id:
-        mcc: 999
-        mnc: 70
+        mcc: 001
+        mnc: 01
       s_nssai:
         - sst: 1
+          sd: 000001
   security:
     integrity_order : [ NIA2, NIA1, NIA0 ]
     ciphering_order : [ NEA0, NEA1, NEA2 ]

--- nrf.yaml.orig       2024-03-24 15:36:48.000000000 +0900
+++ nrf.yaml    2024-03-29 22:38:40.866371099 +0900
@@ -10,8 +10,8 @@
 nrf:
   serving:  # 5G roaming requires PLMN in NRF
     - plmn_id:
-        mcc: 999
-        mnc: 70
+        mcc: 001
+        mnc: 01
   sbi:
     server:
       - address: 127.0.0.10

--- smf.yaml.orig       2024-03-24 15:36:48.000000000 +0900
+++ smf.yaml    2024-03-31 22:45:18.892357262 +0900
@@ -19,35 +19,31 @@
         - uri: http://127.0.0.200:7777
   pfcp:
     server:
-      - address: 127.0.0.4
+      - address: 192.168.0.111
     client:
       upf:
-        - address: 127.0.0.7
-  gtpc:
-    server:
-      - address: 127.0.0.4
+        - address: 192.168.0.112
+          dnn: internet
   gtpu:
     server:
-      - address: 127.0.0.4
+      - address: 192.168.0.111
   metrics:
     server:
       - address: 127.0.0.4
         port: 9090
   session:
     - subnet: 10.45.0.1/16
-    - subnet: 2001:db8:cafe::1/48
+      dnn: internet
   dns:
     - 8.8.8.8
     - 8.8.4.4
-    - 2001:4860:4860::8888
-    - 2001:4860:4860::8844
   mtu: 1400
 #  p-cscf:
 #    - 127.0.0.1
 #    - ::1
 #  ctf:
 #    enabled: auto   # auto(default)|yes|no
-  freeDiameter: /root/open5gs/install/etc/freeDiameter/smf.conf
+#  freeDiameter: /root/open5gs/install/etc/freeDiameter/smf.conf
 
 ################################################################################
 # SMF Info

<a id="changes_up"></a>

Changes in configuration files of Open5GS 5GC U-Plane

--- upf.yaml.orig       2024-03-24 15:36:48.000000000 +0900
+++ upf.yaml    2024-03-29 22:18:51.683148805 +0900
@@ -10,16 +10,17 @@
 upf:
   pfcp:
     server:
-      - address: 127.0.0.7
+      - address: 192.168.0.112
     client:
 #      smf:     #  UPF PFCP Client try to associate SMF PFCP Server
 #        - address: 127.0.0.4
   gtpu:
     server:
-      - address: 127.0.0.7
+      - address: 192.168.0.112
   session:
     - subnet: 10.45.0.1/16
-    - subnet: 2001:db8:cafe::1/48
+      dnn: internet
+      dev: ogstun
   metrics:
     server:
       - address: 127.0.0.7

<a id="changes_srs"></a>

Changes in configuration files of srsRAN 5G ZMQ UE / RAN

<a id="changes_ran"></a>

Changes in configuration files of RAN

See here for the original files.

--- gnb_zmq.yaml.orig   2024-04-23 20:02:09.000000000 +0900
+++ gnb_zmq.yaml        2024-05-12 16:05:48.650203165 +0900
@@ -3,13 +3,21 @@
 # To run the srsRAN Project gNB with this config, use the following command: 
 #   sudo ./gnb -c gnb_zmq.yaml
 
+gnb_id: 0x19B
+
+slicing:
+  - sst: 1
+    sd: 1
+
 amf:
-  addr: 10.53.1.2                  # The address or hostname of the AMF.
-  bind_addr: 10.53.1.1             # A local IP that the gNB binds to for traffic from the AMF.
+  addr: 192.168.0.111                  # The address or hostname of the AMF.
+#  bind_addr: 10.53.1.1             # A local IP that the gNB binds to for traffic from the AMF.
+  n2_bind_addr: 192.168.0.121          # Optional TEXT. Sets local IP address to bind for N2 interface. Format: IPV4 or IPV6 IP address.
+  n3_bind_addr: 192.168.0.121          # Optional TEXT. Sets local IP address to bind for N3 interface. Format: IPV4 or IPV6 IP address.
 
 ru_sdr:
   device_driver: zmq                # The RF driver name.
-  device_args: tx_port=tcp://127.0.0.1:2000,rx_port=tcp://127.0.0.1:2001,base_srate=23.04e6 # Optionally pass arguments to the selected RF driver.
+  device_args: tx_port=tcp://192.168.0.121:2000,rx_port=tcp://192.168.0.122:2001,base_srate=23.04e6 # Optionally pass arguments to the selected RF driver.
   srate: 23.04                      # RF sample rate might need to be adjusted according to selected bandwidth.
   tx_gain: 75                       # Transmit gain of the RF might need to adjusted to the given situation.
   rx_gain: 75                       # Receive gain of the RF might need to adjusted to the given situation.
@@ -20,7 +28,7 @@
   channel_bandwidth_MHz: 20         # Bandwith in MHz. Number of PRBs will be automatically derived.
   common_scs: 15                    # Subcarrier spacing in kHz used for data.
   plmn: "00101"                     # PLMN broadcasted by the gNB.
-  tac: 7                            # Tracking area code (needs to match the core configuration).
+  tac: 1                            # Tracking area code (needs to match the core configuration).
   pdcch:
     common:
       ss0_index: 0                  # Set search space zero index to match srsUE capabilities

<a id="changes_ue"></a>

Changes in configuration files of UE

See here for the original files.

--- ue_zmq.conf.orig    2023-12-07 03:04:57.000000000 +0900
+++ ue_zmq.conf 2024-03-29 22:41:01.107838116 +0900
@@ -6,7 +6,7 @@
 nof_antennas = 1
 
 device_name = zmq
-device_args = tx_port=tcp://127.0.0.1:2001,rx_port=tcp://127.0.0.1:2000,base_srate=23.04e6
+device_args = tx_port=tcp://192.168.0.122:2001,rx_port=tcp://192.168.0.121:2000,base_srate=23.04e6
 
 [rat.eutra]
 dl_earfcn = 2850
@@ -34,9 +34,9 @@
 [usim]
 mode = soft
 algo = milenage
-opc  = 63BFA50EE6523365FF14C1F45F88737D
-k    = 00112233445566778899aabbccddeeff
-imsi = 001010123456780
+opc  = E8ED289DEBA952E4283B54E88E6183CA
+k    = 465B5CE8B199B49FAA5F0A2EE238A6BC
+imsi = 001010000000000
 imei = 353490069873319
 
 [rrc]
@@ -44,11 +44,16 @@
 ue_category = 4
 
 [nas]
-apn = srsapn
+apn = internet
 apn_protocol = ipv4
 
+[slicing]
+enable = true
+nssai-sst = 1
+nssai-sd = 1
+
 [gw]
-netns = ue1
+#netns = ue1
 ip_devname = tun_srsue
 ip_netmask = 255.255.255.0

<a id="network_settings"></a>

Network settings of Open5GS 5GC

<a id="network_settings_up"></a>

Network settings of Open5GS 5GC U-Plane

First, uncomment the next line in the /etc/sysctl.conf file and reflect it in the OS.

net.ipv4.ip_forward=1

# sysctl -p

Next, configure the TUNnel interface and NAPT.

ip tuntap add name ogstun mode tun
ip addr add 10.45.0.1/16 dev ogstun
ip link set ogstun up

iptables -t nat -A POSTROUTING -s 10.45.0.0/16 ! -o ogstun -j MASQUERADE

<a id="build"></a>

Build Open5GS and srsRAN 5G ZMQ UE / RAN

Please refer to the following for building Open5GS and srsRAN 5G ZMQ UE / RAN respectively.

Install MongoDB on Open5GS 5GC C-Plane machine. It is not necessary to install MongoDB on Open5GS 5GC U-Plane machines. MongoDB Compass is a convenient tool to look at the MongoDB database.

<a id="run"></a>

Run Open5GS 5GC and srsRAN 5G ZMQ UE / RAN

First run the 5GC, then the RAN, and the UE.

<a id="run_cp"></a>

Run Open5GS 5GC C-Plane

First, run Open5GS 5GC C-Plane.

./install/bin/open5gs-nrfd &
sleep 2
./install/bin/open5gs-scpd &
sleep 2
./install/bin/open5gs-amfd &
sleep 2
./install/bin/open5gs-smfd &
./install/bin/open5gs-ausfd &
./install/bin/open5gs-udmd &
./install/bin/open5gs-udrd &
./install/bin/open5gs-pcfd &
./install/bin/open5gs-nssfd &
./install/bin/open5gs-bsfd &

<a id="run_up"></a>

Run Open5GS 5GC U-Plane

Next, run Open5GS 5GC U-Plane.

./install/bin/open5gs-upfd &

<a id="run_ran"></a>

Run srsRAN 5G ZMQ RAN

Run srsRAN 5G ZMQ RAN and connect to Open5GS 5GC.

# cd srsRAN_Project/build/apps/gnb
# ./gnb -c gnb_zmq.yaml

The PRACH detector will not meet the performance requirements with the configuration {Format 0, ZCZ 0, SCS 1.25kHz, Rx ports 1}.
Lower PHY in executor blocking mode.

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

Connecting to AMF on 192.168.0.111:38412
Available radio types: zmq.
Cell pci=1, bw=20 MHz, dl_arfcn=368500 (n3), dl_freq=1842.5 MHz, dl_ssb_arfcn=368410, ul_freq=1747.5 MHz

==== gNodeB started ===
Type <t> to view trace

The Open5GS C-Plane log when executed is as follows.

03/30 00:09:23.278: [amf] INFO: gNB-N2 accepted[192.168.0.121]:39830 in ng-path module (../src/amf/ngap-sctp.c:113)
03/30 00:09:23.278: [amf] INFO: gNB-N2 accepted[192.168.0.121] in master_sm module (../src/amf/amf-sm.c:754)
03/30 00:09:23.284: [amf] INFO: [Added] Number of gNBs is now 1 (../src/amf/context.c:1236)
03/30 00:09:23.284: [amf] INFO: gNB-N2[192.168.0.121] max_num_of_ostreams : 30 (../src/amf/amf-sm.c:793)

<a id="run_ue"></a>

Run srsRAN 5G ZMQ UE

Run srsRAN 5G ZMQ UE and connect to Open5GS 5GC.

# cd srsRAN_4G/build/srsue
# ./src/srsue ue_zmq.conf
Reading configuration file ue_zmq.conf...

Built in Release mode using commit ec29b0c1f on branch master.

Opening 1 channels in RF device=zmq with args=tx_port=tcp://192.168.0.122:2001,rx_port=tcp://192.168.0.121:2000,base_srate=23.04e6
Supported RF device list: zmq file
CHx base_srate=23.04e6
Current sample rate is 1.92 MHz with a base rate of 23.04 MHz (x12 decimation)
CH0 rx_port=tcp://192.168.0.121:2000
CH0 tx_port=tcp://192.168.0.122:2001
Current sample rate is 23.04 MHz with a base rate of 23.04 MHz (x1 decimation)
Current sample rate is 23.04 MHz with a base rate of 23.04 MHz (x1 decimation)
Waiting PHY to initialize ... done!
Attaching UE...
Random Access Transmission: prach_occasion=0, preamble_index=0, ra-rnti=0x39, tti=174
Random Access Complete.     c-rnti=0x4601, ta=0
RRC Connected
PDU Session Establishment successful. IP: 10.45.0.2
RRC NR reconfiguration successful.

The Open5GS C-Plane log when executed is as follows.

03/30 00:09:27.594: [amf] INFO: InitialUEMessage (../src/amf/ngap-handler.c:401)
03/30 00:09:27.594: [amf] INFO: [Added] Number of gNB-UEs is now 1 (../src/amf/context.c:2656)
03/30 00:09:27.594: [amf] INFO:     RAN_UE_NGAP_ID[0] AMF_UE_NGAP_ID[1] TAC[1] CellID[0x66c000] (../src/amf/ngap-handler.c:562)
03/30 00:09:27.594: [amf] INFO: [suci-0-001-01-0000-0-0-0000000000] Unknown UE by SUCI (../src/amf/context.c:1840)
03/30 00:09:27.594: [amf] INFO: [Added] Number of AMF-UEs is now 1 (../src/amf/context.c:1621)
03/30 00:09:27.594: [gmm] INFO: Registration request (../src/amf/gmm-sm.c:1224)
03/30 00:09:27.594: [gmm] INFO: [suci-0-001-01-0000-0-0-0000000000]    SUCI (../src/amf/gmm-handler.c:172)
03/30 00:09:27.596: [sbi] WARNING: [UDM] (NRF-discover) NF has already been added [4f2a980e-edde-41ee-a832-ebcdb6a42829:1] (../lib/sbi/nnrf-handler.c:1162)
03/30 00:09:27.597: [sbi] WARNING: NF EndPoint(addr) updated [127.0.0.12:80] (../lib/sbi/context.c:2210)
03/30 00:09:27.597: [sbi] WARNING: NF EndPoint(addr) updated [127.0.0.12:7777] (../lib/sbi/context.c:1946)
03/30 00:09:27.597: [sbi] WARNING: NF EndPoint(addr) updated [127.0.0.12:7777] (../lib/sbi/context.c:1946)
03/30 00:09:27.597: [sbi] WARNING: NF EndPoint(addr) updated [127.0.0.12:7777] (../lib/sbi/context.c:1946)
03/30 00:09:27.597: [sbi] INFO: [UDM] (NF-discover) NF Profile updated [4f2a980e-edde-41ee-a832-ebcdb6a42829:1] (../lib/sbi/nnrf-handler.c:1200)
03/30 00:09:27.600: [sbi] INFO: [UDM] (SCP-discover) NF registered [4f2a980e-edde-41ee-a832-ebcdb6a42829:1] (../lib/sbi/path.c:211)
03/30 00:09:27.706: [sbi] WARNING: [UDR] (NRF-discover) NF has already been added [4f320f12-edde-41ee-aa40-170e22094cf8:1] (../lib/sbi/nnrf-handler.c:1162)
03/30 00:09:27.706: [sbi] WARNING: NF EndPoint(addr) updated [127.0.0.20:80] (../lib/sbi/context.c:2210)
03/30 00:09:27.707: [sbi] WARNING: NF EndPoint(addr) updated [127.0.0.20:7777] (../lib/sbi/context.c:1946)
03/30 00:09:27.707: [sbi] INFO: [UDR] (NF-discover) NF Profile updated [4f320f12-edde-41ee-aa40-170e22094cf8:1] (../lib/sbi/nnrf-handler.c:1200)
03/30 00:09:27.708: [sbi] INFO: [UDR] (SCP-discover) NF registered [4f320f12-edde-41ee-aa40-170e22094cf8:1] (../lib/sbi/path.c:211)
03/30 00:09:27.858: [gmm] INFO: [imsi-001010000000000] Registration complete (../src/amf/gmm-sm.c:2321)
03/30 00:09:27.858: [amf] INFO: [imsi-001010000000000] Configuration update command (../src/amf/nas-path.c:591)
03/30 00:09:27.858: [gmm] INFO:     UTC [2024-03-29T15:09:27] Timezone[0]/DST[0] (../src/amf/gmm-build.c:558)
03/30 00:09:27.858: [gmm] INFO:     LOCAL [2024-03-30T00:09:27] Timezone[32400]/DST[0] (../src/amf/gmm-build.c:563)
03/30 00:09:27.859: [amf] INFO: [Added] Number of AMF-Sessions is now 1 (../src/amf/context.c:2677)
03/30 00:09:27.859: [gmm] INFO: UE SUPI[imsi-001010000000000] DNN[internet] S_NSSAI[SST:1 SD:0x1] smContextRef [NULL] (../src/amf/gmm-handler.c:1285)
03/30 00:09:27.859: [gmm] INFO: SMF Instance [4f3d2294-edde-41ee-b281-f5004b2ffb48] (../src/amf/gmm-handler.c:1324)
03/30 00:09:27.860: [smf] INFO: [Added] Number of SMF-UEs is now 1 (../src/smf/context.c:1019)
03/30 00:09:27.860: [smf] INFO: [Added] Number of SMF-Sessions is now 1 (../src/smf/context.c:3090)
03/30 00:09:27.862: [sbi] WARNING: [UDM] (NRF-discover) NF has already been added [4f2a980e-edde-41ee-a832-ebcdb6a42829:1] (../lib/sbi/nnrf-handler.c:1162)
03/30 00:09:27.862: [sbi] WARNING: NF EndPoint(addr) updated [127.0.0.12:80] (../lib/sbi/context.c:2210)
03/30 00:09:27.862: [sbi] WARNING: NF EndPoint(addr) updated [127.0.0.12:7777] (../lib/sbi/context.c:1946)
03/30 00:09:27.862: [sbi] WARNING: NF EndPoint(addr) updated [127.0.0.12:7777] (../lib/sbi/context.c:1946)
03/30 00:09:27.862: [sbi] WARNING: NF EndPoint(addr) updated [127.0.0.12:7777] (../lib/sbi/context.c:1946)
03/30 00:09:27.862: [sbi] INFO: [UDM] (NF-discover) NF Profile updated [4f2a980e-edde-41ee-a832-ebcdb6a42829:1] (../lib/sbi/nnrf-handler.c:1200)
03/30 00:09:27.865: [sbi] INFO: [UDM] (SCP-discover) NF registered [4f2a980e-edde-41ee-a832-ebcdb6a42829:1] (../lib/sbi/path.c:211)
03/30 00:09:27.867: [sbi] WARNING: [PCF] (NRF-discover) NF has already been added [4f31c57a-edde-41ee-beb6-e328e008752e:1] (../lib/sbi/nnrf-handler.c:1162)
03/30 00:09:27.867: [sbi] WARNING: NF EndPoint(addr) updated [127.0.0.13:80] (../lib/sbi/context.c:2210)
03/30 00:09:27.867: [sbi] WARNING: NF EndPoint(addr) updated [127.0.0.13:7777] (../lib/sbi/context.c:1946)
03/30 00:09:27.867: [sbi] WARNING: NF EndPoint(addr) updated [127.0.0.13:7777] (../lib/sbi/context.c:1946)
03/30 00:09:27.867: [sbi] WARNING: NF EndPoint(addr) updated [127.0.0.13:7777] (../lib/sbi/context.c:1946)
03/30 00:09:27.867: [sbi] INFO: [PCF] (NF-discover) NF Profile updated [4f31c57a-edde-41ee-beb6-e328e008752e:1] (../lib/sbi/nnrf-handler.c:1200)
03/30 00:09:27.869: [sbi] WARNING: [UDR] (NRF-discover) NF has already been added [4f320f12-edde-41ee-aa40-170e22094cf8:1] (../lib/sbi/nnrf-handler.c:1162)
03/30 00:09:27.869: [sbi] WARNING: NF EndPoint(addr) updated [127.0.0.20:80] (../lib/sbi/context.c:2210)
03/30 00:09:27.869: [sbi] WARNING: NF EndPoint(addr) updated [127.0.0.20:7777] (../lib/sbi/context.c:1946)
03/30 00:09:27.869: [sbi] INFO: [UDR] (NF-discover) NF Profile updated [4f320f12-edde-41ee-aa40-170e22094cf8:1] (../lib/sbi/nnrf-handler.c:1200)
03/30 00:09:27.871: [sbi] WARNING: [UDR] (SCP-discover) NF has already been added [4f320f12-edde-41ee-aa40-170e22094cf8:2] (../lib/sbi/path.c:216)
03/30 00:09:27.872: [sbi] WARNING: [BSF] (NRF-discover) NF has already been added [4f2af72c-edde-41ee-9bf5-834c8a50b80e:1] (../lib/sbi/nnrf-handler.c:1162)
03/30 00:09:27.872: [sbi] WARNING: NF EndPoint(addr) updated [127.0.0.15:80] (../lib/sbi/context.c:2210)
03/30 00:09:27.872: [sbi] WARNING: NF EndPoint(addr) updated [127.0.0.15:7777] (../lib/sbi/context.c:1946)
03/30 00:09:27.872: [sbi] INFO: [BSF] (NF-discover) NF Profile updated [4f2af72c-edde-41ee-9bf5-834c8a50b80e:1] (../lib/sbi/nnrf-handler.c:1200)
03/30 00:09:27.873: [sbi] INFO: [BSF] (SCP-discover) NF registered [4f2af72c-edde-41ee-9bf5-834c8a50b80e:1] (../lib/sbi/path.c:211)
03/30 00:09:27.875: [sbi] INFO: [PCF] (SCP-discover) NF registered [4f31c57a-edde-41ee-beb6-e328e008752e:1] (../lib/sbi/path.c:211)
03/30 00:09:27.875: [smf] INFO: UE SUPI[imsi-001010000000000] DNN[internet] IPv4[10.45.0.2] IPv6[] (../src/smf/npcf-handler.c:542)
03/30 00:09:27.876: [gtp] INFO: gtp_connect() [192.168.0.112]:2152 (../lib/gtp/path.c:60)
03/30 00:09:28.014: [sbi] WARNING: [UDM] (NRF-discover) NF has already been added [4f2a980e-edde-41ee-a832-ebcdb6a42829:1] (../lib/sbi/nnrf-handler.c:1162)
03/30 00:09:28.014: [sbi] WARNING: NF EndPoint(addr) updated [127.0.0.12:80] (../lib/sbi/context.c:2210)
03/30 00:09:28.014: [sbi] WARNING: NF EndPoint(addr) updated [127.0.0.12:7777] (../lib/sbi/context.c:1946)
03/30 00:09:28.014: [sbi] WARNING: NF EndPoint(addr) updated [127.0.0.12:7777] (../lib/sbi/context.c:1946)
03/30 00:09:28.014: [sbi] WARNING: NF EndPoint(addr) updated [127.0.0.12:7777] (../lib/sbi/context.c:1946)
03/30 00:09:28.015: [sbi] INFO: [UDM] (NF-discover) NF Profile updated [4f2a980e-edde-41ee-a832-ebcdb6a42829:1] (../lib/sbi/nnrf-handler.c:1200)
03/30 00:09:28.016: [sbi] WARNING: [UDM] (SCP-discover) NF has already been added [4f2a980e-edde-41ee-a832-ebcdb6a42829:2] (../lib/sbi/path.c:216)
03/30 00:09:28.017: [amf] INFO: [imsi-001010000000000:1:11][0:0:NULL] /nsmf-pdusession/v1/sm-contexts/{smContextRef}/modify (../src/amf/nsmf-handler.c:867)
03/30 00:09:28.137: [gmm] INFO: [imsi-001010000000000] No GUTI allocated (../src/amf/gmm-sm.c:1599)

The Open5GS U-Plane log when executed is as follows.

03/30 00:09:27.828: [upf] INFO: [Added] Number of UPF-Sessions is now 1 (../src/upf/context.c:208)
03/30 00:09:27.828: [gtp] INFO: gtp_connect() [192.168.0.111]:2152 (../lib/gtp/path.c:60)
03/30 00:09:27.828: [upf] INFO: UE F-SEID[UP:0x80 CP:0xc81] APN[internet] PDN-Type[1] IPv4[10.45.0.2] IPv6[] (../src/upf/context.c:485)
03/30 00:09:27.828: [upf] INFO: UE F-SEID[UP:0x80 CP:0xc81] APN[internet] PDN-Type[1] IPv4[10.45.0.2] IPv6[] (../src/upf/context.c:485)
03/30 00:09:27.965: [gtp] INFO: gtp_connect() [192.168.0.121]:2152 (../lib/gtp/path.c:60)

The result of ip addr show on VM4 (UE) is as follows.

# ip addr show
...
11: tun_srsue: <POINTOPOINT,MULTICAST,NOARP,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UNKNOWN group default qlen 500
    link/none 
    inet 10.45.0.2/24 scope global tun_srsue
       valid_lft forever preferred_lft forever
...

<a id="ping"></a>

Ping google.com

Specify the TUN interface on VM4 (UE) and try ping.

<a id="ping_1"></a>

Case for going through DN 10.45.0.0/16

Execute tcpdump on VM2 (U-Plane) and check that the packet goes through if=ogstun.

# ping google.com -I tun_srsue -n
PING google.com (172.217.175.110) from 10.45.0.2 tun_srsue: 56(84) bytes of data.
64 bytes from 172.217.175.110: icmp_seq=1 ttl=61 time=75.0 ms
64 bytes from 172.217.175.110: icmp_seq=2 ttl=61 time=90.5 ms
64 bytes from 172.217.175.110: icmp_seq=3 ttl=61 time=63.3 ms

# tcpdump -i ogstun -n
tcpdump: verbose output suppressed, use -v[v]... for full protocol decode
listening on ogstun, link-type RAW (Raw IP), snapshot length 262144 bytes
00:09:34.045185 IP 10.45.0.2 > 172.217.175.110: ICMP echo request, id 9, seq 1, length 64
00:09:34.063643 IP 172.217.175.110 > 10.45.0.2: ICMP echo reply, id 9, seq 1, length 64
00:09:35.056189 IP 10.45.0.2 > 172.217.175.110: ICMP echo request, id 9, seq 2, length 64
00:09:35.081234 IP 172.217.175.110 > 10.45.0.2: ICMP echo reply, id 9, seq 2, length 64
00:09:36.042112 IP 10.45.0.2 > 172.217.175.110: ICMP echo request, id 9, seq 3, length 64
00:09:36.057418 IP 172.217.175.110 > 10.45.0.2: ICMP echo reply, id 9, seq 3, length 64

In addition to ping, you may try to access the web by specifying the TUNnel interface with curl as follows.

# curl --interface tun_srsue google.com
<HTML><HEAD><meta http-equiv="content-type" content="text/html;charset=utf-8">
<TITLE>301 Moved</TITLE></HEAD><BODY>
<H1>301 Moved</H1>
The document has moved
<A HREF="http://www.google.com/">here</A>.
</BODY></HTML>

00:09:38.172434 IP 10.45.0.2.43418 > 172.217.175.110.80: Flags [S], seq 117491664, win 64240, options [mss 1460,sackOK,TS val 2512314474 ecr 0,nop,wscale 7], length 0
00:09:38.189808 IP 172.217.175.110.80 > 10.45.0.2.43418: Flags [S.], seq 18240001, ack 117491665, win 65535, options [mss 1460], length 0
00:09:38.266400 IP 10.45.0.2.43418 > 172.217.175.110.80: Flags [.], ack 1, win 64240, length 0
00:09:38.266562 IP 10.45.0.2.43418 > 172.217.175.110.80: Flags [P.], seq 1:75, ack 1, win 64240, length 74: HTTP: GET / HTTP/1.1
00:09:38.266667 IP 172.217.175.110.80 > 10.45.0.2.43418: Flags [.], ack 75, win 65535, length 0
00:09:38.326674 IP 172.217.175.110.80 > 10.45.0.2.43418: Flags [P.], seq 1:774, ack 75, win 65535, length 773: HTTP: HTTP/1.1 301 Moved Permanently
00:09:38.420663 IP 10.45.0.2.43418 > 172.217.175.110.80: Flags [.], ack 774, win 63467, length 0
00:09:38.420712 IP 10.45.0.2.43418 > 172.217.175.110.80: Flags [F.], seq 75, ack 774, win 63467, length 0
00:09:38.420826 IP 172.217.175.110.80 > 10.45.0.2.43418: Flags [.], ack 76, win 65535, length 0
00:09:38.436939 IP 172.217.175.110.80 > 10.45.0.2.43418: Flags [F.], seq 774, ack 76, win 65535, length 0
00:09:38.474196 IP 10.45.0.2.43418 > 172.217.175.110.80: Flags [.], ack 775, win 63467, length 0

You could now create the end-to-end TUN interface on the DN and send any packets on the network.

In investigating 5G SA, I have built a simulation environment and can now use a very useful system for investigating 5GC and MEC of 5G SA mobile network. I would like to thank the excellent developers and all the contributors of Open5GS, srsRAN Project and srsRAN 4G.

<a id="changelog"></a>

Changelog (summary)