| Harald Welte | f1d4251 | 2017-05-31 21:22:42 +0200 | [diff] [blame] | 1 | = OsmoBSC A / SCCPlite / 3GPP AoIP Options |
| 2 | |
| 3 | == Introduction |
| 4 | |
| 5 | This document serves as a paper to illustrate the different |
| 6 | configurations of OsmoBSC in terms of integration with BTSs and MSCs. |
| 7 | |
| 8 | The document should accompany us in the 2017 development cycle which |
| 9 | includes the _death of the NITB_, i.e. the move away from OsmoNITB to |
| 10 | having OsmoBSC in all configurations, whether with a |
| 11 | proprietary/external MSC or with OsmoMSC. |
| 12 | |
| 13 | Particular attention is spent on the user plane, including aspects |
| 14 | such as |
| 15 | |
| 16 | * user plane transport address handling |
| 17 | * use of MGCP (Media Gateway Control Protocol) |
| 18 | * the (required) evolution of `osmo-bsc_mgcp` |
| 19 | * not loosing classic TDM (E1/T1) BTS support when moving from |
| 20 | OsmoNITB to split OsmoBSC + OsmoMSC setup |
| 21 | |
| 22 | |
| 23 | == Overview |
| 24 | |
| 25 | === Classic GSM RAN with E1 based Abis and E1 A |
| 26 | |
| 27 | This configuration was actually never supported by OpenBSC, as E1 BTS |
| 28 | support was so far for NITB only, but not for OsmoBSC. |
| 29 | |
| 30 | [mscgen] |
| 31 | ---- |
| Oliver Smith | 686deaf | 2018-11-14 10:47:01 +0100 | [diff] [blame] | 32 | include::{srcdir}/mgw/classic-bsc.msc[] |
| Harald Welte | f1d4251 | 2017-05-31 21:22:42 +0200 | [diff] [blame] | 33 | ---- |
| 34 | |
| 35 | === OsmoBSC 2010-2017: IPA-style A over SCCPlite |
| 36 | |
| 37 | This configuration was introduced as early as 2010 in OpenBSC. It |
| 38 | allowed the use of IP based BTSs (ip.access nanoBTS as well as all the |
| 39 | OsmoBTS supported BTS models) in combination with third-party MSCs |
| 40 | implementing a pre-standard, proprietary way of transporting the A |
| 41 | interface over IP at a time where the 3GPP specifications only allowed |
| 42 | classic TDM transport. |
| 43 | |
| 44 | [mscgen] |
| 45 | ---- |
| Oliver Smith | 686deaf | 2018-11-14 10:47:01 +0100 | [diff] [blame] | 46 | include::{srcdir}/mgw/osmo-bsc-old-sccplite.msc[] |
| Harald Welte | f1d4251 | 2017-05-31 21:22:42 +0200 | [diff] [blame] | 47 | ---- |
| 48 | |
| 49 | |
| 50 | === OsmoBSC 2017+: 3GPP AoIP + Abis/IP |
| 51 | |
| 52 | Release 7 of 3GPP included an official specification on how an |
| 53 | interoperable A-over-IP (AoIP) interface shall look like. |
| 54 | |
| 55 | As more modern MSCs at operators tend to favor implementing 3GPP AoIP |
| 56 | rather than the proprietary SCCPlite based A interface, it becomes |
| Martin Hauke | a29affd | 2019-11-13 22:10:41 +0100 | [diff] [blame^] | 57 | necessary for OsmoBSC to support this. |
| Harald Welte | f1d4251 | 2017-05-31 21:22:42 +0200 | [diff] [blame] | 58 | |
| 59 | At the same time, for compatibility reasons, the classic SCCPlite |
| 60 | support shall be kept, if possible with reasonable effort. |
| 61 | |
| 62 | [mscgen] |
| 63 | ---- |
| Oliver Smith | 686deaf | 2018-11-14 10:47:01 +0100 | [diff] [blame] | 64 | include::{srcdir}/mgw/osmo-bsc-new-mgw.msc[] |
| Harald Welte | f1d4251 | 2017-05-31 21:22:42 +0200 | [diff] [blame] | 65 | ---- |
| 66 | |
| 67 | |
| 68 | === OsmoBSC 2017+: 3GPP AoIP + Abis/E1 |
| 69 | |
| 70 | Since OsmoNITB will soon be deprecated, we will use OsmoBSC in all |
| 71 | Osmocom GSM ntework setups, requiring the support for classic E1/T1 |
| 72 | based BTSs from OsmoBSC. |
| 73 | |
| 74 | [mscgen] |
| 75 | ---- |
| Oliver Smith | 686deaf | 2018-11-14 10:47:01 +0100 | [diff] [blame] | 76 | include::{srcdir}/mgw/osmo-bsc-new-mgw-e1.msc[] |
| Harald Welte | f1d4251 | 2017-05-31 21:22:42 +0200 | [diff] [blame] | 77 | ---- |