Osmocom Network In The Box » History » Revision 17
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h1. Osmocom Network In The Box
h2. OsmoNITB R.I.P., long live the Network In The Box
Historically, Osmocom offered the [[OsmoNITB:]] "Network-In-The-Box" as an actual single program. It was a useful simplification at the time, but in 2017, Osmocom have decided to split OsmoNITB into programs more closely resembling traditional network architecture. It is recommended to use the new separate components instead of the OsmoNITB, since active development focus has moved there.
It is still very much possible to run a complete Osmocom core network in one "box". For example, a sysmoBTS can run the entire core network on the same hardware that drives the TRX, making it a complete network in actually one single box. At the same time, having separate components also allows scaling to large deployments, with properly distributed load and a central subscriber database.
To migrate from OsmoNITB to the new separate programs, see the [[OsmoNITB Migration Guide]].
h2. Part of this Complete Network
Assuming that you have your radio hardware ready (a BTS, a femto cell or an SDR driven by osmo-trx), the core network consists of separate programs providing voice/SMS/USSD ("circuit-switched") and data ("packet-switched") services.
h3. Circuit-Switched Components
To run a circuit-switched core network, you need:
* [[OsmoHLR:]] -- Home Location Register, stores subscriber IMSI, phone number and auth tokens.
* [[OsmoMSC:]] -- Mobile Switching Center, handles signalling, i.e. attach/detach of subscribers, call establishment, messaging (SMS and USSD).
* [[OsmoMGW:]] -- Media Gateway, is instructed by the MSC and/or the BSC to direct RTP streams for active voice calls.
* [[OsmoSTP:]] -- Signal Transfer Point, routes SCCP messages between MSC, BSC, HNBGW and for 3G also the SGSN.
* [[OsmoBSC:]] -- 2G Base Station Controller, manages logical channels and other lower level aspects for one or more 2G BTS; it is technically part of the BSS and not the "core network".
* [[OsmoHNBGW:]] -- 3G HomeNodeB Gateway, receives the Iuh protocol from a 3G femto cell and forwards to MSC and SGSN by SCCP/M3UA via OsmoSTP.
h3. Packet-Switched Components
* [[OpenGGSN:|OsmoGGSN]] -- Gateway GPRS Support Node, "opens" GTP tunnels received from SGSNs to internet uplink.
* [[OsmoSGSN:]] -- Serving GPRS Support Node, handles signalling, i.e. attach/detach of subscribers and PDP contexts.
* [[OsmoHLR:]] -- same as for circuit switched, see above.
* [[OsmoHNBGW:]] -- for 3G packet switched networks, same as for 3G circuit switched, see above.
* ([[OsmoPCU:]] -- for 2G networks, a component closely tied to the BTS, drives the TRX and ties to the SGSN via Gb-interface.)
h1. Configuration Example
h2. Have to Know
Each program features a detailed [[Osmocom Manuals|user manual]], your primary source of information to expand on the setup described here.
Osmocom offers [[Nightly Builds|compiled packages for various distributions]]. If you're up to it, you may also [[Build from Source]].
Each Osmocom program typically has
* a distinct configuration file;
* a VTY telnet console for live interaction;
* a CTRL interface for live interaction with 3rd party programs.
h2. OsmoHLR
See the [[Osmocom Manuals|manual]] on creating a subscriber database, and add one or more subscribers.
While you do need one, your configuration file may actually remain empty. This will serve GSUP on localhost (127.0.0.1), sufficient for a Network In The Box.
h2. OsmoMSC
The VLR component of OsmoMSC needs to connect to the OsmoHLR's GSUP server to know which subscribers are authorized. By default, it will connect to OsmoHLR on localhost, no explicit config needed.
To be reachable by OsmoBSC and OsmoHNBGW, it needs an SCCP point code, and it needs to connect to OsmoSTP to make itself known to SCCP routing.
* There is a default point code, currently 0.23.1 (in 8.8.3 point code format).
* OsmoMSC will by default look for OsmoSTP on localhost's M3UA port, 2905.
To direct RTP streams, OsmoMSC needs an OsmoMGW instance. By default, it will look for an MGW on localhost and the default MGCP port, 4222.
Again, your config file may remain empty.
h2. OsmoMGW
The Media Gateway receives instructions in the form of MGCP messages from OsmoMSC. It forwards RTP streams directly between BTS, femto cells and remote endpoints, e.g. other MGW instances.
Its RTP IP address must be reachable by the BTS / the femto cell.
* In a setup that truly runs in one box (e.g. sysmoBTS or osmo-trx with co-located core network), this may be localhost (127.0.0.1).
* With a separate BTS or RNC (e.g. 3G femto cell or nanoBTS), make sure to configure an IP address that is reachable.
*osmo-mgw.cfg*
<pre>
mgcp
local ip 192.168.0.3
bind ip 192.168.0.3
</pre>
The default is to allow any BTS / femto cell IP address to connect.
(Near future: a second OsmoMGW may be needed to run alongside each OsmoBSC instance.)
h2. OsmoSTP
OsmoSTP acts as a server for routing messages. OsmoMSC, OsmoBSC, OsmoHNBGW and OsmoSGSN contact OsmoSTP and announce their own point code, after which they may instruct OsmoSTP to route SCCP messages to each other by these point codes.
The basic configuration that permits dynamic routing is:
*osmo-stp.cfg*
<pre>
cs7 instance 0
xua rkm routing-key-allocation dynamic-permitted
listen m3ua 2905
accept-asp-connections dynamic-permitted
</pre>
h2. OsmoBSC
OsmoBSC needs to register with OsmoSTP, and contact the MSC by its point code.
OsmoBSC also needs complete configuration of all connected BTS. This example shows configuration for a sysmoBTS.
Furthermore, some network properties need to be set.
The 'gprs mode' determines whether packet switched access will be enabled. 'gprs mode none' switches off data services, as osmo-bts will not contact osmo-pcu to establish data service. This is a configuration without packet switched service:
*osmo-bsc.cfg* for voice only
<pre>
network
network country code 901
mobile network code 70
mm info 1
short name Osmocom
long name Osmocom
auth policy closed
encryption a5 0
bts 0
type sysmobts
band GSM-1800
cell_identity 0
location_area_code 23
ip.access unit_id 1800 0
gprs mode none
trx 0
rf_locked 0
arfcn 868
nominal power 23
timeslot 0
phys_chan_config CCCH+SDCCH4
timeslot 1
phys_chan_config SDCCH8
timeslot 2
phys_chan_config TCH/H
timeslot 3
phys_chan_config TCH/H
timeslot 4
phys_chan_config TCH/H
timeslot 5
phys_chan_config TCH/H
timeslot 6
phys_chan_config TCH/H
timeslot 7
phys_chan_config TCH/H
cs7 instance 0
! osmo-bsc's own point code
point-code 0.42.0
! address book entry named 'msc_remote', used below
sccp-address msc_remote
point-code 0.23.1
msc 0
msc-addr msc_remote
</pre>
To allow data service, set a 'gprs mode gprs' or 'gprs mode egprs', and configure PDCH timeslots. Traditionally, a fixed amount of TCH timeslots for voice and PDCH timeslots for data service are configured. OsmoBTS also supports two types of dynamic timeslots, as described in the "Abis manual":http://ftp.osmocom.org/docs/latest/osmobts-abis.pdf, chapter "Dynamic Channel Combinations". The following is a configuration with data service based on Osmocom style dynamic timeslots:
*osmo-bsc.cfg* for voice and data service
<pre>
network
network country code 901
mobile network code 70
mm info 1
short name Osmocom
long name Osmocom
auth policy closed
encryption a5 0
bts 0
type sysmobts
band GSM-1800
cell_identity 0
location_area_code 23
ip.access unit_id 1800 0
gprs mode gprs
trx 0
rf_locked 0
arfcn 868
nominal power 23
timeslot 0
phys_chan_config CCCH+SDCCH4
timeslot 1
phys_chan_config SDCCH8
timeslot 2
phys_chan_config TCH/F_TCH/H_PDCH
timeslot 3
phys_chan_config TCH/F_TCH/H_PDCH
timeslot 4
phys_chan_config TCH/F_TCH/H_PDCH
timeslot 5
phys_chan_config TCH/F_TCH/H_PDCH
timeslot 6
phys_chan_config TCH/F_TCH/H_PDCH
timeslot 7
phys_chan_config PDCH
cs7 instance 0
! osmo-bsc's own point code
point-code 0.42.0
! address book entry named 'msc_remote', used below
sccp-address msc_remote
point-code 0.23.1
msc 0
msc-addr msc_remote
</pre>
h2. OsmoHNBGW
For connecting a 3G hNodeB (femto cell), OsmoHNBGW is needed to receive Iuh and forward IuCS and IuPS. (For a pure 2G setup, no HNBGW is needed.)
OsmoHNBGW needs to connect to OsmoSTP for routing, and needs to know the MSC and SGSN point codes.
It must also be reachable by the hNodeB, hence its Iuh must typically run on a public IP, not a loopback address like 127.0.0.1.
*osmo-hnbgw.cfg*
<pre>
cs7 instance 0
! OsmoHNBGW's own local point code
point-code 0.3.0
! Address book entries, used below
sccp-address msc
point-code 0.23.1
sccp-address sgsn
point-code 0.23.2
hnbgw
iuh
local-ip 192.168.0.3
iucs
remote-addr msc
iups
remote-addr sgsn
</pre>
h2. OsmoGGSN
To provide packet switched service, OsmoGGSN must offer GTP service to the OsmoSGSN. Notably, both OsmoGGSN and OsmoSGSN must use identical port numbers, which an intrinsic requirement of the GTP protocol. Hence they must not run on the same IP address. It is sufficient to, for example, run OsmoGGSN on 127.0.0.2, and OsmoSGSN's GTP on 127.0.0.1.
OsmoGGSN maintains a gsn_restart counter, to be able to reliably communicate to the SGSN that it has restarted. This is kept in the 'state-dir', by default in /tmp.
It also needs access to a tun device. This may be configured ahead of time, so that OsmoGGSN does not need root privileges. If run with 'sudo', OsmoGGSN may also create its own tun device. In below example, the 'tun4' device has been created ahead of time. IPv4 operation is enabled by default, but for future compatibility, it is good to indicate that explicitly.
OsmoGGSN furthermore indicates DNS servers, as well as an IPv4 address range to assign to subscribers' PDP contexts.
*osmo-ggsn.cfg*
<pre>
ggsn ggsn0
gtp bind-ip 127.0.0.2
apn internet
tun-device tun4
type-support v4
ip dns 0 192.168.100.1
ip dns 1 8.8.8.8
ip ifconfig 176.16.222.0/24
ip prefix dynamic 176.16.222.0/24
</pre>
h2. OsmoSGSN
OsmoSGSN needs to reach the GGSN to establish GTP tunnels for subscribers. It must have a separate GTP IP address from OsmoGGSN, as mentioned before.
For 2G, OsmoSGSN needs to be reachable by the PCU, and needs a public IP for the Gb interface if it is not running directly on the BTS hardware (e.g. on sysmoBTS or when using osmo-trx). For 2G operation, SGSN and GGSN may both use a local IP address for GTP, as long as they differ (e.g. 127.0.0.1 and 127.0.0.2).
For 3G, OsmoSGSN needs to be reachable by both the HNBGW for IuPS as well as by the hNodeB for GTP, i.e. it definitely needs to have a public IP address for the GTP port. IuPS may remain local if both HNBGW and SGSN are on the same box.
Finally, OsmoSGSN needs access to OsmoHLR to access subscriber data. Set 'auth-policy remote' to use the HLR for subscriber authorization. The default
*osmo-sgsn.cfg*
<pre>
sgsn
gtp local-ip 192.168.0.3
ggsn 0 remote-ip 192.168.0.142
auth-policy remote
gsup remote-ip 127.0.0.1
</pre>
h1. Running Example
Each Osmocom program comes with a systemd service file. It is recommended to place config files in /etc/osmocom/ and launch the individual components using systemd.
When installed from debian or opkg feeds, you will find the systemd service files in /lib/systemd/system/.
Re/starting and stopping then works like this:
<pre>
systemctl restart osmo-hlr
systemctl stop osmo-hlr
</pre>
Depending on the system's logging configuration, logs may be visible in /var/log/daemon.log, or by journalctl:
<pre>
journalctl -f -u osmo-hlr
</pre>
When journalctl is used, it may be necessary to enable it first, e.g. by setting "Storage=volatile" in /etc/systemd/journald.conf followed by a 'systemctl restart systemd-journald'.
A sure way to see the logs is to 'systemctl stop' a service and run it manually; remember to start the service again when done debugging.
For illustration, the manual command invocations for the components would look like this:
<pre>
osmo-hlr -l hlr.db -c osmo-hlr.cfg
osmo-msc -c osmo-msc.cfg
osmo-mgw -c osmo-mgw.cfg
osmo-stp -c osmo-stp.cfg
osmo-bsc -c osmo-bsc.cfg
osmo-hnbgw -c osmo-hnbgw.cfg
osmo-ggsn -c osmo-ggsn.cfg
osmo-sgsn -c osmo-sgsn.cfg
</pre>
