OsmoGGSN and Linux Kernel accelerated GTP-U

OsmoGGSN has support to use the Linux kernel GTP-U code to accelerate the data/user plane while still implementing the control plane (GTP-C) in userspace in OsmoGGSN.

For more information about the Linux kernel GTP-U code, please see linux-kernel-gtp-u

Building OsmoGGSN with kernel which has GTP-U support

At the time of writing (2018-04-26) of this wiki, below listed distributions have support of GTP kernels :

  • Debian
    • Debian 9 "stretch" (kernel 4.9.0-6)
    • Debian 10 "buster"
    • Debian "unstable"
  • Ubuntu
    • Ubuntu 16.04 "xenial" (kernel 4.8, 4.10, 4.13)
    • Ubuntu 17.10 "artful" (kernel 4.13)
  • OpenSUSE
    • OpenSUSE Tumbleweed (kernel "stable" 4.8, 4.12)
  • Fedora

If you're using any other distribution, or are building your own kernels, please verify that CONFIG_GTP is set to either m or y.

If CONFIG_GTP is not enabled, you cannot use kernel GTP-U!

Check if package libc-ares-dev is installed and if not please add it.

Installing dependencies and build library libosmocore

You can install required dependency packages with:

$ sudo apt install libtalloc-dev libpcsclite-dev

Please follow instructions provided at Build from source in order to install libosmocore

Installing dependencies and build library libgtpnl

You can install dependencies with:

$ sudo apt install libmnl-dev

Then build libgtpnl like this

$ git clone
$ cd libgtpnl
$ autoreconf -fi
$ ./configure
$ make
$ sudo make install
$ sudo ldconfig


Build OsmoGGSN like this:

$ git clone
$ cd osmo-ggsn
$ ./configure --enable-gtp-linux
$ make
$ sudo make install
$ sudo ldconfig

Following message is shown at end of the command: ./configure --enable-gtp-linux

OsmoGGSN Configuration:
  GTP Linux kernel support:            yes

This means that appropriate header files are available.

Using OsmoGGSN with kernel which has GTP-U support

In order to find out whether gtp.ko module is available we can enter following command:

$ find /lib/modules/$(uname -r) -name gtp.ko

Output below shows that gtp.ko module is present:


We are loading module gtp from kernel issuing command:

sudo modprobe gtp

when you enter:

$ lsmod | grep gtp

then more information about gtp and related udp tunnel can be obtained:

gtp                    28672  0
udp_tunnel             16384  1 gtp

Some helpful tools are available in: libgtpnl/tools

you can get more details about gtp-tunnel, entering command from the OsmoGGSN shell:

$ sudo ./gtp-tunnel list

Output will be similar to:

version 1 tei 1/0 ms_addr sgsn_addr

Note: OsmoGGSN is started by:

$ sudo osmo-ggsn -c osmo-ggsn.cfg

Related output should be similar to the one shown below:

<0002> ggsn.c:186 APN(internet): Starting
<0002> ggsn.c:204 APN(internet): Opening Kernel GTP device tun4
<0002> ggsn.c:215 APN(internet): Skipping APN start
<0002> ggsn.c:794 GGSN(ggsn0): Starting GGSN
<000d> gtp.c:902 GTP: gtp_newgsn() started at
<0002> ggsn.c:830 GGSN(ggsn0): Successfully started
<0002> ggsn.c:186 APN(internet): Starting
<0002> ggsn.c:204 APN(internet): Opening Kernel GTP device tun4
<0002> gtp-kernel.c:79 Initialized GTP kernel mode (genl ID is 25)
<0001> tun.c:217 GTP kernel configured
<0002> ggsn.c:236 APN(internet): Setting tun IP address
<0002> ggsn.c:294 APN(internet): Creating IPv4 pool
<0002> ggsn.c:168 APN(internet): Blacklist tun IP
<0002> ggsn.c:325 APN(internet): Successfully started
<0005> telnet_interface.c:104 Available via telnet 4260
<000c> control_if.c:916 CTRL at 4257

You can now start to establish PDP contexts to your new osmo-ggsn instance, from OsmoSGSN, sgsnemu or third-party SGSNs

Automatic Testing

See Automatic_Testing for the automatic continuous integration test setup.

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Updated by laforge over 1 year ago · 12 revisions

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