Cellular Network Infrastructure

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).

* [[OsmoSTP:]] -- Signal Transfer Point, routes SCCP messages between MSC, BSC, HNBGW and for 3G also the SGSN.

* [[OsmoMGW:]] -- Media Gateway, is instructed by the MSC and/or the BSC to direct RTP streams for active voice calls.

* [[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.)