Open5GS-OAI

Open5GS contains a series of software components and network functions that implement the 4G/ 5G NSA and 5G SA core functions. The main difference of NSA (Non-Standalone Architecture) and SA (Standalone Architecture) is that NSA anchors the control signaling of 5G Radio Networks to the 4G Core, while the SA scheme connects the 5G Radio directly to the 5G core network, and the control signaling does not depend on the 4G network at all. NSA, as the name suggests, is a 5G service that does not ‘stand alone’ but is built over an existing 4G network. SA, on the other hand, allows completely independent operation of a 5G service without any interaction with an existing 4G core.

Per 3GPP TR 21.915, Two deployment options are defined for 5G:

1. The “Non-Stand Alone” (NSA) architecture, where the 5G Radio Access Network (AN) and its New Radio (NR) interface is used in conjunction with the existing LTE and EPC infrastructure Core Network (respectively 4G Radio and 4G Core), thus making the NR technology available without network replacement. In this configuration, only the 4G services are supported, but enjoying the capacities offered by the 5G New Radio (lower latency, etc). The NSA is also known as “E-UTRA-NR Dual Connectivity (EN-DC)” or “Architecture Option 3”.
2. The “Stand-Alone” (SA) architecture, where the NR is connected to the 5G CN. Only in this configuration, the full set of 5G Phase 1 services are supported.

4G/ 5G NSA Core

The Open5GS 4G/ 5G NSA Core contains the following components:

MME - Mobility Management Entity
HSS - Home Subscriber Server
PCRF - Policy and Charging Rules Function
SGWC - Serving Gateway Control Plane
SGWU - Serving Gateway User Plane
PGWC/SMF - Packet Gateway Control Plane / (component contained in Open5GS SMF)
PGWU/UPF - Packet Gateway User Plane / (component contained in Open5GS UPF)

Install Open5GS

Ubuntu 20.04 Ubuntu makes it easy to install Open5GS as shown below,

$ sudo apt update
$ sudo apt install software-properties-common
$ sudo add-apt-repository ppa:open5gs/latest
$ sudo apt update
$ sudo apt install open5gs

Install the WebUI of Open5GS

The WebUI allows you to interactively edit subscriber data.

$ sudo apt update
$ sudo apt install curl
$ curl -fsSL https://deb.nodesource.com/setup_14.x | sudo -E bash -
$ sudo apt install nodejs
$ curl -fsSL https://open5gs.org/open5gs/assets/webui/install | sudo -E bash -

Configure Open5GS

There are some tweaks you will need to make to the config files

Setup a 5G Core

Each VMs are as follows.
VM # SW & Role IP address OS Memory (Min) HDD (Min)
VM1 Open5GS EPC C-Plane 192.168.0.111/24 Ubuntu 20.04 1GB 20GB
VM2 Open5GS EPC U-Plane1 192.168.0.112/24 Ubuntu 20.04 1GB 20GB
VM3 Open5GS EPC U-Plane2 192.168.0.113/24 Ubuntu 20.04 1GB 20GB
VM4 OpenAirInterface UE / RAN 192.168.0.120/24 Ubuntu 18.04 2GB 40GB
OAI UE / RAN cannot be built on Ubuntu 20.04, so build it on Ubuntu 18.04

Subscriber Information (other information is the same) is as follows. UE # IMSI APN OP/OPc
UE0 001010000000100 internet OPc
UE1 001010000000101 internet2 OPc
UE2 001010000000102 internet2 OPc
UE3 001010000000103 ims OPc
UE4 001010000000104 ims OPc

Changes in configuration files of Open5GS EPC C-Plane

First, copy .yaml files to have a backup
then do all of the change like below and check with diff -u command
Modify /etc/open5gs/mme.yaml to set the S1AP IP address, PLMN ID, and TAC.

open5gs/install/etc/open5gs/mme.yaml
open5gs/install/etc/open5gs/sgwc.yaml
open5gs/install/etc/open5gs/smf.yaml

Then you can check the modifications with the below command:
$ diff -u /etc/open5gs/mme.yaml.old /etc/open5gs/mme.yaml
Finally, you can check differences between the original files and uploaded in Core folder.

Changes in configuration files of Open5GS EPC U-Plane1 & 2

open5gs/install/etc/open5gs/sgwu.yaml
open5gs/install/etc/open5gs/upf.yaml

Finally, you can check differences between the original files and uploaded in U-plane1&2 folders.

Register Subscriber Information

Connect to http://localhost:3000 and login with admin account.

Username : admin
Password : 1423

Network settings of Open5GS EPC and OAI UE / RAN

Network settings of Open5GS EPC U-Plane1

First, uncomment the next line in the /etc/sysctl.conf file and reflect it in the OS.
net.ipv4.ip_forward=1
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
$ ip tuntap add name ogstun2 mode tun
$ ip addr add 10.46.0.1/16 dev ogstun2
$ ip link set ogstun2 up
$ iptables -t nat -A POSTROUTING -s 10.46.0.0/16 ! -o ogstun2 -j MASQUERADE

Network settings of Open5GS EPC U-Plane2

First, uncomment the next line in the /etc/sysctl.conf file and reflect it in the OS.
net.ipv4.ip_forward=1
Next, configure the TUNnel interface and NAPT.
$ ip tuntap add name ogstun3 mode tun
$ ip addr add 10.47.0.1/16 dev ogstun3
$ ip link set ogstun3 up
$ iptables -t nat -A POSTROUTING -s 10.47.0.0/16 ! -o ogstun3 -j MASQUERADE

UE and eNB installation

$ git clone https://gitlab.eurecom.fr/oai/openairinterface5g/ enb_folder
$ cd enb_folder
$ git checkout -f v1.0.0
$ cd ..
$ cp -Rf enb_folder ue_folder

Changes in configuration files of UE & eNB

enb_folder/ci-scripts/conf_files/rcc.band7.tm1.nfapi.conf
ue_folder/ci-scripts/conf_files/ue.nfapi.conf
ue_folder/openair3/NAS/TOOLS/ue_eurecom_test_sfr.conf
Finally, you can check differences between the original files and uploaded in UERAN1 folders.
Note: UERAN2 file are the same with UERAN1, it is for the case that you want to have more than one eNB and more UEs

Changes in configuration files of RAN

$ enb_folder/ci-scripts/conf_files/rcc.band7.tm1.nfapi.conf

$ sudo ifconfig lo: 127.0.0.2 netmask 255.0.0.0 up

Build the eNB

$ cd enb_folder
$ source oaienv
$ cd cmake_targets
(If you test less than 16 UEs, type below command.)
$ ./build_oai -I --eNB -t ETHERNET -c
(If you test more than 16 UEs, type below command and this command also can be used in case of less than 16 UEs)
$ ./build_oai -I --eNB -t ETHERNET -c --mu

Build the UEs

$ cd ue_folder
$ source oaienv
$ cd cmake_targets
(If you test less than 16 UEs, type below command.)
$ ./build_oai -I --UE -t ETHERNET -c
(If you test more than 16 UEs, type below command and this command also can be used in case of less than 16 UEs.)
$ ./build_oai -I --UE -x -t ETHERNET -c --musim
$ cd ue_folder/targets/bin/
$ cp .u* ../../cmake_targets/
$ cp usim ../../cmake_targets/
$ cp nvram ../../cmake_targets/

Run OAI RAN

$ cd ~/enb_folder/cmake_targets
$ ./lte_build_oai/build/lte-softmodem -O ../ci-scripts/conf_files/rcc.band7.tm1.nfapi.conf 2>&1 | tee enb.log

Run OAI UEs

$ cd ue_folder/cmake_targets/tools
$ source init_nas_s1 UE
$ cd ~/ue_folder/cmake_targets/tools
$ source init_nas_s1 UE
$ cd ..
$ ./lte_build_oai/build/lte-uesoftmodem -O ../ci-scripts/conf_files/ue.nfapi.conf --L2-emul 3 --num-ues 5 2>&1 | tee ue.log

Related references

https://open5gs.org/open5gs/docs/
https://github.com/s5uishida/open5gs_epc_oai_sample_config
https://gitlab.eurecom.fr/oai/openairinterface5g/-/wikis/l2-nfapi-simulator/l2-nfapi-simulator-w-S1-same-machine

Logs

to see each daemon logs just simply type the below command:
$ journalctl -u open5gs-mmed -f

Help & Support

Having trouble?
Just ask ! between 5 and 10 days I will respond.