erGW - 3GPP GGSN and PDN-GW in Erlang

This is a 3GPP GGSN and PDN-GW implemented in Erlang. It strives to eventually support all the functionality as defined by 3GPP TS 23.002 Section 4.1.3.1 for the GGSN and Section 4.1.4.2.2 for the PDN-GW.

IMPLEMENTED FEATURES

Messages:

• GTPv1 Create/Update/Delete PDP Context Request on Gn
• GTPv2 Create/Delete Session Request on S5/S8

From the above the following procedures as defined by 3GPP T 23.060 should work:

• PDP Context Activation/Modification/Deactivation Procedure
• PDP Context Activation/Modification/Deactivation Procedure using S4
• Intersystem Change Procedures (handover 2G/3G/LTE)
• 3GPP TS 23.401 Annex D, Interoperation with Gn/Gp SGSNs procedures (see CONFIG.md)

RADIUS over Gi/SGi

The GGSN Gn interface supports RADIUS over the Gi interface as specified by 3GPP TS 29.061 Section 16. At the moment, only the Authentication and Authorization is supported, Accounting is not supported.

See RADIUS.md for a list of supported Attrbiutes.

Many thanks to On Waves for sponsoring the RADIUS Authentication implementation.

MISSING FEATURES

The following procedures are assumed/known to be NOT working:

• Secondary PDP Context Activation Procedure
• Secondary PDP Context Activation Procedure using S4

Other shortcomings:

• QoS parameters are hard-coded

BUILDING

The minimum supported Erlang version is 19.0.

Using tetrapak:

# tetrapak build check

Using rebar:

# rebar3 compile

RUNNING

A erGW installation needs a data path provider to handle the GTP-U path. This instance can be installed on the same host or a different host.

• for a data path suitable for GGSN/PGW see: GTP-u-KMod
• for a data path suitable for GTPhub see: GTP-u-EDP

erGW can be started with the normal Erlang command line tools, e.g.:

erl -setcookie secret -sname ergw -config ergw.config
Erlang/OTP 19 [erts-8.0.3] [source] [64-bit] [async-threads:10] [kernel-poll:false]

Eshell V8.0.3  (abort with ^G)
(ergw@localhost)1> application:ensure_all_started(ergw).

This requires a suitable ergw.config, e.g.:

[{setup, [{data_dir, "/var/lib/ergw"},
          {log_dir,  "/var/log/gtp-c-node"}                             %% NOTE: lager is not using this
         ]},

 {ergw, [{sockets,
          [{irx, [{type, 'gtp-c'},
                  {ip,  {192,0,2,16}},
                  {netdev, "grx"},
                  freebind
                 ]},
           {grx, [{type, 'gtp-u'},
                  {node, 'gtp-u-node@localhost'},
                  {name, 'grx'}]}
          ]},

         {vrfs,
          [{upstream, [{pools,  [{{10, 180, 0, 1}, {10, 180, 255, 254}, 32},
                                 {{16#8001, 0, 0, 0, 0, 0, 0, 0}, {16#8001, 0, 0, 16#FFFF, 0, 0, 0, 0}, 64}
                                ]},
                       {'MS-Primary-DNS-Server', {8,8,8,8}},
                       {'MS-Secondary-DNS-Server', {8,8,4,4}},
                       {'MS-Primary-NBNS-Server', {127,0,0,1}},
                       {'MS-Secondary-NBNS-Server', {127,0,0,1}}
                      ]}
          ]},

         {handlers,
          [{gn, [{handler, pgw_s5s8},
                 {sockets, [irx]},
                 {data_paths, [grx]},
                 {aaa, [{'Username',
                         [{default, ['IMSI', <<"@">>, 'APN']}]}]}
                ]},
           {s5s8, [{handler, pgw_s5s8},
                   {sockets, [irx]},
                   {data_paths, [grx]}
                  ]}
          ]},

         {apns,
          [{[<<"example">>, <<"net">>], [{vrf, upstream}]}
          ]}
        ]},

 {ergw_aaa, [
             %% {ergw_aaa_provider, {ergw_aaa_mock, [{secret, <<"MySecret">>}]}}
             {ergw_aaa_provider,
              {ergw_aaa_radius,
               [{nas_identifier,<<"nas01.example.com">>},
                {radius_auth_server,{{192,0,2,32},1812,<<"secret">>}},
                {radius_acct_server,{{192,0,2,32},1813,<<"secret">>}}
               ]}
             }
            ]},

 {lager, [
          {log_root, "/var/log/gtp-c-node"},
          {colored, true},
          {handlers, [
                      {lager_console_backend, debug},
                      {lager_file_backend, [{file, "error.log"}, {level, error}]},
                      {lager_file_backend, [{file, "console.log"}, {level, debug}]}
                     ]}
         ]}
].

The configuration is documented in CONFIG.md

This process can be simplified by using enit. A sample config that only requires minimal adjustment for IP's, hostnames and interfaces can be found in priv/enit/ggsn. Install those files to / (root) and start with enit startfg ergw.