NextEPC provides the MME (Mobility Management Engine), which terminates the S1 interfaces from the eNodeBs cells in the cellular network, and interfaces via S11 to the SGW as well as via S6a to the HSS.
NextEPC provides the SGW (Serving Gateway) which is situated between the MME and PGW. It implements the S11 interface to the MME, and the S5 interface to the PGW.
NextEPC provides the PGW or PDN-GW (Packet Data Network Gateway) element of the EPC, i.e. the gateway between the EPC and the external packet data network, such as the public Internet. It implements the S5 interface towards the S-GW, the SGi interface towards the Internet, and the S7 interface towards the PCRF.
NextEPC provides the HSS (Home Subscriber Server) element of the EPC, i.e. the central database of mobile network subscribers, with their IMSI, MSISDN, cryptographic key materials, service subscription information, etc. It implements the S6a interface towards the MME using the DIAMETER protocol.
NextEPC contains the PCRF (Policy and Charging Rules Function), which controls the service quality (QoS) of individual connections and how to account/charge related traffic. It implements the Gx interface towards the PGW using the DIAMETER protocol.
This post will guide you on how to get installed **NextEPC** with your environment. To date, NextEPC has been tested on GNU/Linux distributions(Debian, Ubuntu, CentOS, Fedora), FreeBSD, and Mac OS X.
The NextEPC service is registered in `systemd` environment, and is started automatically during the installation phase. The service names are *nextepc-mmed*, *nextepc-sgwd*, *nextepc-pgwd*, *nextepc-hssd*, and *nextepc-pcrfd*. You can use the `systemctl` command to control specific services.
```bash
sudo systemctl status nextepc-mmed (Check the service status)
sudo systemctl stop nextepc-mmed (Stop the service)
sudo systemctl disable nextepc-mmed (Will not be started after rebooting)
sudo systemctl enable nextepc-mmed (Will be started after rebooting)
sudo systemctl start nextepc-mmed (Start the service)
sudo systemctl restart nextepc-mmed (Stop and start)
```
* ### Web User Interface
The LTE user subcription information of NextEPC is stored and maintained by [Mongo DB](https://www.mongodb.com/). To manage the subscriber information, [Mongo DB client](https://docs.mongodb.com/ecosystem/tools/) is required, and this client can connect to the DB URI [_mongodb://localhost/nextepc_].
NextEPC provides an alternative management interface for customers to manage their subscriber information in an easy way, that is **Web User Interface**. The following shows how to install the Web UI of NextEPC.
For these OS, you should build NextEPC from the code. First clone this [repository](https://github.com/acetcom/nextepc.git) and then follow instructions described in the [documentation](http://nextepc.org/docs/).
Since NextEPC is an open source project, you can build and use this program directly from source code. If you have already installed it with a package manager, or are not interested in learning the source code, you can skip this guide and proceed to the next [configuration guide](http://nextepc.org/guides/3-configuration).
NextEPC requires MongoDB and TUN device. If you have previously installed NextEPC according to the [Installation Guide](http://nextepc.org/guides/1-installation), they was configured at that time. So, you can skip this step.
To run NextEPC with least privilege, TUN device permission should be a `crw-rw-rw-`(666). Otherwise, you need to run nextepc daemon with root privilege. If the permission is not `crw-rw-rw-`(666), you may need to install `udev` package. Nevertheless, if the permission do not change , you can run nextepc with root privileges or change the permission using `chmod 666 /dev/net/tun`.
We provide a program that checks whether the installation is correct. After running the wireshark, select `loopback` interface, filter `s1ap || diameter || gtpv2 || gtp` and run `./test/testepc`. You can see the virtually created packets. [[testepc.pcapng]](http://nextepc.org/static/pcapng/testepc.pcapng)
It is a convenient tool called `nextepc-epcd` for developers. This daemon includes both *MME*, *SGW*, *PGW*, *HSS*, and *PCRF*. So, instead of running all 5 daemons, you can just run `nextepc-epcd` in your development environment.
When you run `nextepc-epcd`, all logs for MME, SGW, PGW, PCRF, and HSS are written to `nextepc.log`, and all settings are managed in one place for `nextepc.conf`. You can find the log/conf path at the beginning of running screen.
Now the web server is running on _http://localhost:3000_.
Configuraiton
=============
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](http://yaml.org/)-format configuration files in `/etc/nextepc/*.conf`.
Note that [/etc/nextepc/nextepc.conf](https://github.com/acetcom/nextepc/blob/master/support/config/nextepc.conf.in) 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.
```yaml
mme:
freeDiameter: mme.conf
s1ap:
addr: <ipaddress>
...
```
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.
```yaml
sgw:
gtpc:
addr: 127.0.0.2
gtpu:
addr: <ipaddress>
...
```
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](https://en.wikipedia.org/wiki/Network_address_translation) 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:
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. The `eth0` shown below is just an example. Do not miss out on modifying your interface name(e.g `enp0s25`, `wls3`).
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`.
