5G IMS Operators

5G IMS is used to deploy a standalone working 5G IMS setup. It is implemented as microk8s applications using Juju Charms and Microk8s. It consists of the following 6 IMS components as charms,

pcscf: Proxy-Call Session Control Function stands as the entry and exit to any request to IMS
icscf: Interrogating Call Session Control Function is the entity that selects the appropriate SCSCF during registration
scscf: Serving-Call Session Control Function checks for the authentication data of UE
hss: Home subscriber server maintains user profile and location details
dns: Domain Name Service is a custom dns server for communication between IMS components
mysql: Database of IMS for storing user profile and location data

Usage

Prepare environment

A. Install Microk8s

a. Install Microk8s using the following commands,

sudo snap install microk8s --classic --channel 1.19/stable
sudo usermod -a -G microk8s `whoami`
newgrp microk8s
microk8s.status --wait-ready

The ouput "microk8s is running" signifies that Microk8s is successfully installed.

b. Enable the following required addons for Microk8s to deploy 5G IMS

microk8s.enable storage dns
microk8s.enable multus
microk8s.enable rbac
microk8s.enable metallb

NOTE: 5G IMS requires 2 loadbalancer IP addresses mandatorily. So allocate 2 IP addresses while enabling metallb.

B. Install Juju

a. Install Juju with the following commands,

sudo snap install juju --classic --channel 2.8/stable
juju bootstrap microk8s

Deploy

Deploy from local repository

a. Clone the 5G-IMS repository

git clone https://github.com/charmed-osm/5g-ims.git
cd 5g-ims/

b. Enable Microk8s registry for storing images

microk8s.enable registry

c. Build 5G IMS images

./build_docker_images.sh

d. Push built images to registry

sudo docker push localhost:32000/ims_pcscf:1.0
sudo docker push localhost:32000/ims_scscf:1.0
sudo docker push localhost:32000/ims_icscf:1.0
sudo docker push localhost:32000/ims_hss:1.0
sudo docker push localhost:32000/ims_dns:1.0

f. Execute the following script to build all the 5G IMS charms using Charmcraft,

./build_charms.sh

g. Create a model in Juju and deploy 5G IMS,

juju add-model ims
juju deploy ./bundle.yaml

h. Editing coredns,

microk8s.kubectl edit cm -n kube-system coredns

Add the following content in to coredns,

mnc001.mcc001.3gppnetwork.org:53 {
errors
cache 30
forward . <ims_dns_service_ip>
}

where ims_dns_service_ip is the Cluster service IP of DNS application.

To check logs in coredns,

microk8s.kubectl logs --namespace=kube-system -l k8s-app=kube-dns

Once the changes are updated successfully, “Reloading complete” can be seen in the logs.

Integration

5G IMS exposes its following services as loadbalancer services in order to facilitate IMS SIP calls.

PCSCF TCP Service - To enable reachability to PCSCF service from extenal.
HSS Service - To enable HSS GUI

In order to achieve this, 5G IMS needs 2 Loadbalancer services to be exposed and published. This is done using,

microk8s.enable metallb

NOTE: 5G IMS requires 2 loadbalancer IP addresses mandatorily. Ignore this step if already done in pre-requisites.

Juju Actions:

a. Action "add-user" is used to add users to ims,

juju run-action hss/0 add-user user=jack password=jack domain=mnc001.mcc001.3gppnetwork.org implicit=3 --wait

Where unit-id is the unit number, user and password can be given to be added to ims, domain is the default domain available in ims, implicit id should be given as unique per user.

b. Action "log-level", is used to change the log-levels. Debug-values can be given from 2-5,

juju run-action pcscf/0 log-level debug=3 --wait
juju run-action scscf/0 log-level debug=3 --wait
juju run-action icscf/0 log-level debug=3 --wait

Where unit-id is the unit number of the respective unit and debug is the log level that has to be set for PCSCF, SCSCF and ICSCF respectively.

Check for the status of the action in the output which should be "completed".

Actions Verification

a. Action “add-user” can be verified in MySQL application with the following,

mysql -u root -p root
use hss_db;
select * from impi;

Verify that the users added from actions are listed in the impi table.

b. Action "log-level" can be verified in ICSCF, SCSCF and PCSCF as follows,

Login to PCSCF/SCSCF/ICSCF pod, open the kamailio_pcscf.log or kamailio_scscf.log or kamailio_pcscf.log file and check for the following line,

“core.debug has been changed to 3"

Verify that the log-level given from action and the log level shown in the above line are the same.

5G Scenarios

5G User Registration

After 5G-Core(https://github.com/charmed-osm/5g-core) and 5G-RAN(https://github.com/charmed-osm/5g-ran) are deployed and actions are completed, the user registration can be triggered through the following rest API call with POST method,

http://ran-loadbalancerip:8081/attachtrigger/1

Sample response for successful attach, Response Message: "Triggered Attach for the requested UE!" Response Code: 200 OK

Internet Traffic Flow

Once registration is successful, 5G-RAN's UE application would be enabled to access the data network. Test the following in UE application,

a. ICMP TRAFFIC

ping 8.8.8.8

b. TCP TRAFFIC

wget google.com

c. UDP TRAFFIC

nc -u <netcat server-ip> port

where netcat server-ip is the IP address of the server where netcat server is running. Note: for UDP traffic netcat server should be running in another server. To do that use the following commands in another server.

apt-get install netcat
nc -u -l -p <any unused port>

Voice Traffic Flow

Voice traffic flow can be tested once 5G-Core(https://github.com/charmed-osm/5g-core), 5G-RAN(https://github.com/charmed-osm/5g-ran) and 5G-IMS are deployed and actions are completed. To test voice traffic flows, a SIP client called PJSIP is already installed in the UE application. Follow the below steps in UE application,

a. Traverse to /pjproject directory in the UE pod.

b. alice.cfg is configured for an user named alice which is already available in IMS by default.

Note: The username, password and id can be changed to any user added from day-2 action of IMS as well.

c. Add the following content to /etc/hosts file,

<PCSCF_LB_IP> mnc001.mcc001.3gppnetwork.org <PCSCF-LB_IP> pcscf.mnc001.mcc001.3gppnetwork.org

Where <PCSCF-LB_IP> is the loadbalancer IP of PCSCF application and mnc001.mcc001.3gppnetwork.org is the domain added in coredns of IMS cluster.

d. Execute the following command to register the user alice with IMS,

pjsua --config-file alice.cfg --log-level=3

Note: Peform the above steps to register another user say bob with IMS so that SIP calls can be tested between the two users. This has to be done in another UE pod. You can scale the ue charm in RAN, enter to the pod, and in the alice.cfg file, replace "alice" with "bob".

e. After registration of both users, press ‘m’ from UE application's alice and then press enter to initiate a SIP call.

f. Give bob’s id and then press enter. The message “Calling” can be observed in alice’s UE pod.

g. Then in bob’s server, the following message can be seen,

Press ‘a’ to answer or ‘h’ to hangup

h. Press a and then enter. Then the following message will be displayed,

Answer with code:

i. Type 200 and enter.

j. After this “Confirmed” message can be seen in both alice and bob indicating that the call between alice and bob is successful and that RTP packets are being sent between alice and bob. The same can be verified by capturing SIP packets using ngrep, tcpdump or wireshark.

k. Then to end/hangup the call, press h and then enter from alice. Verify the “Disconnected” message in both alice and bob.

Testing

Run Integration and Unit tests to test and verify the 5G IMS Charms.

Integration tests

Functional tests for 5G IMS were created using zaza.

Install tox

apt-get install tox

Run Integration Test

To run zaza integration test,

tox -e func_test

This command will create a model, deploy the charms, run tests and destroy the model

Unit tests

Unit tests has to be executed in all the 5G IMS components/charms. The following commands show how to perform unit test in PCSCF,

cd charms/pcscf-operator
./run_tests

Similarly, unit tests can be run for all the other components/charms.

Get in touch

Found a bug?: https://github.com/charmed-osm/5g-ims/issues Email: canonical@tataelxsi.onmicrosoft.com