| = OsmoBSC A / SCCPlite / 3GPP AoIP Options |
| |
| == Introduction |
| |
| This document serves as a paper to illustrate the different |
| configurations of OsmoBSC in terms of integration with BTSs and MSCs. |
| |
| The document should accompany us in the 2017 development cycle which |
| includes the _death of the NITB_, i.e. the move away from OsmoNITB to |
| having OsmoBSC in all configurations, whether with a |
| proprietary/external MSC or with OsmoMSC. |
| |
| Particular attention is spent on the user plane, including aspects |
| such as |
| |
| * user plane transport address handling |
| * use of MGCP (Media Gateway Control Protocol) |
| * the (required) evolution of `osmo-bsc_mgcp` |
| * not loosing classic TDM (E1/T1) BTS support when moving from |
| OsmoNITB to split OsmoBSC + OsmoMSC setup |
| |
| |
| == Overview |
| |
| === Classic GSM RAN with E1 based Abis and E1 A |
| |
| This configuration was actually never supported by OpenBSC, as E1 BTS |
| support was so far for NITB only, but not for OsmoBSC. |
| |
| [mscgen] |
| ---- |
| include::mgw/classic-bsc.msc[] |
| ---- |
| |
| === OsmoBSC 2010-2017: IPA-style A over SCCPlite |
| |
| This configuration was introduced as early as 2010 in OpenBSC. It |
| allowed the use of IP based BTSs (ip.access nanoBTS as well as all the |
| OsmoBTS supported BTS models) in combination with third-party MSCs |
| implementing a pre-standard, proprietary way of transporting the A |
| interface over IP at a time where the 3GPP specifications only allowed |
| classic TDM transport. |
| |
| [mscgen] |
| ---- |
| include::mgw/osmo-bsc-old-sccplite.msc[] |
| ---- |
| |
| |
| === OsmoBSC 2017+: 3GPP AoIP + Abis/IP |
| |
| Release 7 of 3GPP included an official specification on how an |
| interoperable A-over-IP (AoIP) interface shall look like. |
| |
| As more modern MSCs at operators tend to favor implementing 3GPP AoIP |
| rather than the proprietary SCCPlite based A interface, it becomes |
| neccessary for OsmoBSC to support this. |
| |
| At the same time, for compatibility reasons, the classic SCCPlite |
| support shall be kept, if possible with reasonable effort. |
| |
| [mscgen] |
| ---- |
| include::mgw/osmo-bsc-new-mgw.msc[] |
| ---- |
| |
| |
| === OsmoBSC 2017+: 3GPP AoIP + Abis/E1 |
| |
| Since OsmoNITB will soon be deprecated, we will use OsmoBSC in all |
| Osmocom GSM ntework setups, requiring the support for classic E1/T1 |
| based BTSs from OsmoBSC. |
| |
| [mscgen] |
| ---- |
| include::mgw/osmo-bsc-new-mgw-e1.msc[] |
| ---- |