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Configuration

In LTE, there are tons of configurable parameters. This page will guide you to set essential parameters up. The configuration consists of three parts: IP network connectivity, LTE network settings and Subscribers registering.

1. IP Connectivity between Network Entities

The minimum requirement of having IP connectvity is to modify the configuration files of MME and SGW. Once NextEPC has been installed, you can find YAML-format configuration files in /etc/nextepc/*.conf.

Note that /etc/nextepc/nextepc.conf is just a manual. If you use nextepc-epcd in a build environment, this configuration file could be used, but if you installed it with the package manager, modifying this configuration file has no effect.

Anyway, before setting up, please decide a network interface to run NextEPC, and then the IP address of the interface needs to be recorded in the configuration files.

Modification of MME config

Open /etc/nextepc/mme.conf file, and find an item in mme → s1ap. Please set your IP address with putting addr: keyword.

mme:
    freeDiameter: mme.conf
    s1ap:
      addr: <IP address>
...

Save and exit.

Modification of SGW config

Open /etc/nextepc/sgw.conf file, and find an item in sgw → gtpu. Please set your IP address with putting addr: keyword.

sgw:
    gtpc:
      addr: 127.0.0.2
    gtpu:
      addr: <IP address>
...

Save and exit.

Adding a route for UE to have Internet connectivity

By default, a LTE UE will receive a IP address with the network address of 45.45.0.0/16. If you have a NAT router (e.g., wireless router, cable modem, etc), the LTE UE can reach Internet in uplink, but it cannot in downlink. It's because the NAT router has no idea on 45.45.0.0/16, so adding a route is required. Please refer to the user manual to know how to add a static route in your router.

Add a route of both 45.45.0.0/16 and cafe::0/64 to go the PGW IP address. For example, a command for Linux will be:

sudo ip route add 45.45.0.0/16 via <'PGW IP address'>
sudo ip route add cafe::0/64 via <'PGW IP address'>

If you have no NAT router, there is another option for you. iptables can solve the problem. You execute the following command in NextEPC installed host. Do not miss out on modifying your interface name(e.g enp0s25, wls3).

sudo sh -c "echo 1 > /proc/sys/net/ipv4/ip_forward"
sudo iptables -t nat -A POSTROUTING -o <'interface-name'> -j MASQUERADE
sudo iptables -I INPUT -i pgwtun -j ACCEPT

2. LTE Network Settings

PLMN and TAC

By default, LTE PLMN and TAC are set as shown in the following:

mme:
    gummei: 
      plmn_id:
        mcc: 001
        mnc: 01
      mme_gid: 2
      mme_code: 1
    tai:
      plmn_id:
        mcc: 001
        mnc: 01
      tac: 12345

The LTE EnodeBs need to be set to use the same values of PLMN and TAC in NextEPC. If you want to change them, please modifiy in /etc/nextepc/mme.conf.

Restarting MME and SGW.

After changing conf files, please restart NextEPC daemons.

sudo systemctl restart nextepc-mmed
sudo systemctl restart nextepc-sgwd

3. Register a subscriber

Open http://localhost:3000. Login with admin. Later, you can change the password in Account Menu.

  - Username : admin
  - Password : 1423

Using Web UI, you can add a subscriber without a Mongo DB client.

  - Go to Subscriber Menu.
  - Click `+` Button to add a new subscriber.
  - Fill the IMSI, security context(K, OPc, AMF), and APN of the subscriber.
  - Click `SAVE` Button

This addition affects immediately NextEPC without restaring any daemon.

Appendix

When you install NextEPC for the first time, the default configuration looks like this:

Network

* MME
  S1AP: listen on all address avaiable in system
  GTP-C: listen on the first IP address in system
  DIAMETER: 127.0.0.2 (No TLS)

* SGW
  GTP-C: 127.0.0.2
  GTP-U: listen on the first IP address in system

* PGW
  GTP-C: Both 127.0.0.3 and [::1]
  GTP-U: Both 127.0.0.3 and [::1]
  DIAMETER: 127.0.0.3 (No TLS)

* HSS
  DIAMETER: 127.0.0.4 (No TLS)

* PCRF
  DIAMETER: 127.0.0.5 (No TLS)

GUMMEI, PLMN and TAC

* GUMMEI
  PLMN ID - MNC: 001, MCC: 01
  MME Group : 2
  MME Code : 1

* TAI
  PLMN ID - MNC: 001, MCC: 01
  TAC : 12345

Security

* Integrity : EIA1 - Snow 3G
* Ciphering : EEA0 - Nothing

UE Network

* IPv4 : 45.45.0.1/16
* IPv6 : cafe::1/64

DNS

* IPv4
  Primary : 8.8.8.8 
  Secondary : 8.8.4.4

* IPv6
  Primary : 2001:4860:4860::8888
  Secondary : 2001:4860:4860::8844