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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.
CONTENTS
- IMPLEMENTED FEATURES
- EXPERIMENTAL FEATURES
- USER PLANE
- DIAMETER and RADIUS over Gi/SGi
- POLICY CONTROL
- ONLINE/OFFLINE CHARING
- MISSING FEATURES
- ERLANG Version Support
- DOCKER IMAGES
- BUILDING & RUNNING
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:
- Sect. 5.4.2.2, HSS Initiated Subscribed QoS Modification (without PCRF)
- Annex D, Interoperation with Gn/Gp SGSNs procedures (see CONFIG.md)
EXPERIMENTAL FEATURES
Experimental features may change or be removed at any moment. Configuration settings for them are not guaranteed to work across versions. Check CONFIG.md and NEWS.md on version upgrades.
- rate limiting, defaults to 100 requests/second
- metrics, see METRICS.md
USER PLANE
erGW uses the 3GPP control and user plane separation (CUPS) of EPC nodes architecture as layed out in 3GPP TS 23.214 and 3GPP TS 29.244.
DIAMETER and RADIUS over Gi/SGi
The SAE-GW, PGW and GGSN interfaces supports DIAMETER and RADIUS over the Gi/SGi interface as specified by 3GPP TS 29.061 Section 16. This support is experimental in this version and not all aspects are functional. For RADIUS only the Authentication and Authorization is full working, Accounting is experimental and not fully supported. For DIAMETER NASREQ only the Accounting is working.
See RADIUS.md for a list of supported Attrbiutes.
Many thanks to On Waves for sponsoring the RADIUS Authentication implementation.
Example of configuration RADIUS:
%% ...
{ergw_aaa, [
{handlers, [
{ergw_aaa_static, [
{'Node-Id', <<"CHANGE-ME">>}, %% <- CHANGE
{'NAS-Identifier', <<"CHANGE-ME">>}, %% <- CHANGE
{'NAS-IP-Address', {127,0,0,3}}, %% <- CHANGE
{'Acct-Interim-Interval', 1800}, %% <- CHANGE
{'Framed-Protocol', 'PPP'},
{'Service-Type', 'Framed-User'}
]},
{ergw_aaa_radius, [
{server,
{{127,0,0,4}, 1813, <<"CHANGE-ME-SECRET">>} %% <- CHANGE IP and SECRET
},
{termination_cause_mapping, [
{normal, 1},
{administrative, 6},
{link_broken, 2},
{upf_failure, 9},
{remote_failure, 9},
{cp_inactivity_timeout, 4},
{up_inactivity_timeout, 4},
{'ASR', 6},
{error, 9},
{peer_restart, 7}
]}
]}
]},
{services, [
{'Default', [
{handler, 'ergw_aaa_static'}
]},
{'RADIUS-Acct', [
{handler, 'ergw_aaa_radius'}
]}
]},
{apps, [
{default, [
{session, ['Default']},
{procedures, [
{authenticate, []},
{authorize, []},
{start, ['RADIUS-Acct']},
{interim, ['RADIUS-Acct']},
{stop, ['RADIUS-Acct']}
]}
]}
]}
]},
%% ...
Example of configuration epc-ocs function of DIAMETER:
%% ...
{ergw_aaa, [
%% ...
{functions, [
{'epc-ocs', [
{handler, ergw_aaa_diameter},
{'Origin-Host', <<"CHANGE-ME">>}, %% <- CHANGE: Origin-Host needs to be resolvable
%% to local IP (either through /etc/hosts or DNS)
{'Origin-Realm', <<"CHANGE-ME">>}, %% <- CHANGE
{transports, [
[
{connect_to, <<"aaa://CHANGE-ME;transport=tcp">>}, %% <- CHANGE
{recbuf,131072}, %% <- CHANGE
{sndbuf,131072} %% <- CHANGE
]
]}
]}
]},
%% ...
]},
%% ...
Example of configuration ergw-pgw-epc-rf function of DIAMETER:
%% ...
{ergw_aaa, [
%% ...
{functions, [
{'ergw-pgw-epc-rf', [
{handler, ergw_aaa_diameter},
{'Origin-Host', <<"CHANGE-ME">>}, %% <- CHANGE
{'Origin-Realm', <<"CHANGE-ME">>}, %% <- CHANGE
{transports, [
[
{connect_to, <<"aaa://CHANGE-ME;transport=tcp">>}, %% <- CHANGE
{recbuf,131072}, %% <- CHANGE
{reuseaddr,false}, %% <- CHANGE
{sndbuf,131072} %% <- CHANGE
]
]}
]},
]},
{handlers, [
%% ...
{ergw_aaa_rf, [
{function, 'ergw-pgw-epc-rf'},
{'Destination-Realm', <<"CHANGE-ME">>} %% <- CHANGE
]},
{termination_cause_mapping, [
{normal, 1},
{administrative, 4},
{link_broken, 5},
{upf_failure, 5},
{remote_failure, 1},
{cp_inactivity_timeout, 4},
{up_inactivity_timeout, 4},
{'ASR', 6},
{error, 9},
{peer_restart, 1}
]}
%% ...
]},
{services, [
%% ...
{'Rf', [{handler, 'ergw_aaa_rf'}]},
%% ...
]},
{apps, [
{default, [
%% ...
{procedures, [
%% ...
{ {rf, 'Initial'}, ['Rf']},
{ {rf, 'Update'}, ['Rf']},
{ {rf, 'Terminate'}, ['Rf']},
%% ...
]}
]}
%% ...
]}
]},
%% ...
POLICY CONTROL
DIAMETER is Gx is supported as experimental feature. Only Credit-Control-Request/Answer (CCR/CCA) and Abort-Session-Request/Answer (ASR/ASA) procedures are supported. Re-Auth-Request/Re-Auth-Answer (RAR/RAA) procedures are not supported.
ONLINE/OFFLINE CHARING
Online charging through Gy is in beta quality with the following known caveats:
- When multiple rating groups are in use, CCR Update requests will contain unit reservation requests for all rating groups, however they should only contain the entries for the rating groups where new quotas, threshold and validity's are needed.
Offline charging through Rf is supported in beta quality in this version and works only in "independent online and offline charging" mode (tight interworking of online and offline charging is not supported).
Like on Gx only CCR/CCR and ASR/ASA procredures are supported.
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
ERLANG Version Support
All minor version of the current major release and the highest minor version of
the previous major release will be supported.
Due to a bug in OTP 22.x, the netdev configuration option of erGW is broken
(see). If you need this feature, you
must use OTP 23.x.
When in doubt check the otp_release section in .github/workflows/main.yml for tested
versions.
DOCKER IMAGES
Docker images are build by GitHub Actions and pushed to hub.docker.com, and by gitlab.com and pushed to quay.io.
BUILDING DOCKER IMAGE
erGW Docker image can be get from quay.io. For create a new image based on ergw-c-node from quay.io need run second command:
$ docker run -t -i --rm quay.io/travelping/ergw-c-node:2.4.2 -- /bin/sh
/ # cd opt
/opt # ls
ergw-c-node
BUILDING & RUNNING
REQUIRED
- Erlang OTP 23.2.7 is the recommended version.
- Rebar3 An erGW installation needs a user plane provider to handle the GTP-U path. This instance can be installed on the same or different host.
A suitable user plane node based on VPP can be found at VPP-UFP.
CONFIGURATION
erGW can be started with rebar3 command line tools, and build with run can looks like:
$ git clone https://github.com/travelping/ergw.git
$ cd ergw
$ wget https://s3.amazonaws.com/rebar3/rebar3
$ chmod u+x ./rebar3
$ touch ergw.config
Then fill just created ergw.config file with content like described below providing a suitable configuration, e.g.:
%-*-Erlang-*-
[{setup, [{data_dir, "/var/lib/ergw"},
{log_dir, "/var/log/ergw-c-node"}
]},
{kernel,
[{logger,
[{handler, default, logger_std_h,
#{level => info,
config =>
#{sync_mode_qlen => 10000,
drop_mode_qlen => 10000,
flush_qlen => 10000}
}
}
]}
]},
{ergw, [{'$setup_vars',
[{"ORIGIN", {value, "epc.mnc001.mcc001.3gppnetwork.org"}}]},
{plmn_id, {<<"001">>, <<"01">>}},
{http_api,
[{port, 8080},
{ip, {0,0,0,0}}
]},
{node_id, <<"pgw.$ORIGIN">>},
{sockets,
[{cp, [{type, 'gtp-u'},
{vrf, cp},
{ip, {127,0,0,1}},
freebind,
{reuseaddr, true}
]},
{irx, [{type, 'gtp-c'},
{vrf, epc},
{ip, {127,0,0,1}},
{reuseaddr, true}
]},
{sx, [{type, 'pfcp'},
{socket, cp},
{ip, {172,21,16,2}}
]}
]},
{vrfs,
[{sgi, [{pools, [{{10, 106, 0, 1}, {10, 106, 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,
[{'h1', [{handler, pgw_s5s8},
{protocol, gn},
{sockets, [irx]},
{node_selection, [default]}
]},
{'h2', [{handler, pgw_s5s8},
{protocol, s5s8},
{sockets, [irx]},
{node_selection, [default]}
]}
]},
{apns,
[{[<<"tpip">>, <<"net">>], [{vrf, sgi}]},
{[<<"APN1">>], [{vrf, sgi}]}
]},
{teid, {3, 6}}, % {teid, {Prefix, Length}} - optional, default: {0, 0}
{metrics, [
{gtp_path_rtt_millisecond_intervals, [10, 100]} % optional, default: [10, 30, 50, 75, 100, 1000, 2000]
]},
{node_selection,
[{default,
{static,
[
%% APN NAPTR alternative
{"_default.apn.$ORIGIN", {300,64536},
[{"x-3gpp-upf","x-sxb"}],
"topon.sx.prox01.$ORIGIN"},
%% A/AAAA record alternatives
{"topon.sx.prox01.$ORIGIN", [{127,0,0,1}], []}
]
}
}
]
},
{nodes,
[{default,
[{vrfs,
[{cp, [{features, ['CP-Function']}]},
{epc, [{features, ['Access']}]},
{sgi, [{features, ['SGi-LAN']}]}]
},
{heartbeat, [
{interval, 5000},
{timeout, 500},
{retry, 5}
]},
{request,
[{timeout, 30000},
{retry, 5}]}]
}]
},
{path_management, [
{t3, 10000},
{n3, 5},
{echo, 60000},
{idle_timeout, 1800000},
{idle_echo, 600000},
{down_timeout, 3600000},
{down_echo, 600000},
{icmp_error_handling, immediate} % optional, can be 'ignore' | 'immediate', by default: immediate
]}
]},
{ergw_aaa,
[{handlers,
[{ergw_aaa_static,
[{'NAS-Identifier', <<"NAS-Identifier">>},
{'Acct-Interim-Interval', 600},
{'Framed-Protocol', 'PPP'},
{'Service-Type', 'Framed-User'},
{'Node-Id', <<"PGW-001">>},
{'Charging-Rule-Base-Name', <<"cr-01">>},
{rules, #{'Default' =>
#{'Rating-Group' => [3000],
'Flow-Information' =>
[#{'Flow-Description' => [<<"permit out ip from any to assigned">>],
'Flow-Direction' => [1] %% DownLink
},
#{'Flow-Description' => [<<"permit out ip from any to assigned">>],
'Flow-Direction' => [2] %% UpLink
}],
'Metering-Method' => [1],
'Precedence' => [100]
}
}
}
]}
]},
{services,
[{'Default', [{handler, 'ergw_aaa_static'}]}
]},
{apps,
[{default,
[{session, ['Default']},
{procedures, [{authenticate, []},
{authorize, []},
{start, []},
{interim, []},
{stop, []}
]}
]}
]}
]},
{jobs, [{samplers,
[{cpu_feedback, jobs_sampler_cpu, []}
]},
{queues,
[{path_restart,
[{regulators, [{counter, [{limit, 100}]}]},
{modifiers, [{cpu_feedback, 10}]} %% 10 = % increment by which to modify the limit
]},
{create,
[{max_time, 5000}, %% max 5 seconds
{regulators, [{rate, [{limit, 100}]}]},
{modifiers, [{cpu_feedback, 10}]} %% 10 = % increment by which to modify the limit
]},
{delete,
[{regulators, [{counter, [{limit, 100}]}]},
{modifiers, [{cpu_feedback, 10}]} %% 10 = % increment by which to modify the limit
]},
{other,
[{max_time, 10000}, %% max 10 seconds
{regulators, [{rate, [{limit, 1000}]}]},
{modifiers, [{cpu_feedback, 10}]} %% 10 = % increment by which to modify the limit
]}
]}
]}
].
COMPILE & RUN
$ ./rebar3 compile
$ sudo ./rebar3 shell --setcookie secret --sname ergw --config ergw.config --apps ergw
===> Verifying dependencies...
CONFIG: enabling persistent_term support
===> Analyzing applications...
===> Compiling ergw
Erlang/OTP 23 [erts-11.0.3] [source] [64-bit] [smp:8:8] [ds:8:8:10] [async-threads:1] [hipe]
Eshell V11.0.3 (abort with ^G)
(ergw@localhost)1> application:info().
The configuration is documented in CONFIG.md
RUNNING UNIT TEST
Unit test can be run local with:
$ rebar ct
In order to run the IPv6 a number of locap IPv6 addresses have to be added to the host. Check .github/workflows/main.yml or .gitlab-ci.yml the list.
The DNS resolver tests can be run with a local DNS server. The docker image use with the CI test can also be use for that.
Run it with:
docker run -d --rm \
--name=bind9 \
--publish 127.0.10.1:53:53/udp \
--publish 127.0.10.1:53:53/tcp \
--publish 127.0.10.1:953:953/tcp \
quay.io/travelping/ergw-dns-test-server:latest
and
export CI_DNS_SERVER=127.0.10.1
before running the unit tests.
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