| OsmoPCU Gb Protocol Specification |
| ================================= |
| Harald Welte <hwelte@sysmocom.de> |
| |
| == Introduction |
| |
| This document describes the Gb interface of *OsmoPCU*. Based on 3GPP TS |
| 08.16 and 08.18, this document indicates which of the 3GPP specified Gb |
| messages and IEs are implemented according to 3GPP specifications, which of |
| these are not or not fully implemented, as well as OsmoPCU-specific extensions |
| to the Gb interface not specified by 3GPP. |
| |
| Extensions to the Gb interface specific to OsmoPCU are detailed in this |
| document. For details on the messages and IEs that comply with above-mentioned |
| 3GPP specifications, please refer to those documents. |
| |
| .3GPP document versions referred to by this document |
| [cols="20%,80%"] |
| |=== |
| |3GPP TS 08.56 | version 8.0.1 Release 1999 |
| |3GPP TS 08.58 | version 8.6.0 Release 1999 |
| |3GPP TS 08.60 | version 8.2.1 Release 1999 |
| |3GPP TS 12.21 | version 8.0.0 Release 1999 |
| |3GPP TS 08.16 | version 8.0.1 Release 1999 |
| |3GPP TS 08.18 | version 8.12.0 Release 1999 |
| |=== |
| |
| .IETF documents referred to by his document |
| [cols="20%,80%"] |
| |=== |
| |IETF RFC 768 | User Datagram Protocol |
| |IETF RFC 791 | Internet Protocol |
| |=== |
| |
| == Overview |
| |
| The OsmoPCU Gb interface consists of the NS (Network Services) and |
| BSSGP (Base Station Subsystem Gateway Protocol), encapsulated in UDP |
| (User Datagram Protocol) and IP (Internet Protocol) version 4. |
| Use of other underlying protocols (e. g. Frame Relay) is not supported. |
| |
| .UDP port numbers used by OsmoPCU Gb/IP |
| [options="header",width="50%",cols="35%,65%"] |
| |=== |
| |TCP Port Number|Usage |
| |23000|NS over UDP |
| |=== |
| |
| The NS-over-UDP link is established in the PCU -> SGSN direction, i.e. |
| the PCU is running as client while the SGSN is running as server. |
| |
| Establishment of the NS-over-UDP link is only possible after OsmoPCU |
| has been configured via the *PCU socket* interface from OsmoBTS. |
| |
| OsmoBTS in turn receives relevant configuration parameters from |
| OsmoBSC or the BSC component inside OsmoNITB. |
| |
| .Overview of Gb link establishment |
| ["mscgen"] |
| ---- |
| include::gb/gb-startup.msc[] |
| ---- |
| |
| [[ident]] |
| === Identities |
| |
| The Gb interface identities of the PCU are configured via BSC -> |
| OsmoBTS -> PCU Socket. They consist of |
| |
| NSEI:: NS Equipment Identifier |
| NSVCI:: NS Virtual Connection Identifier |
| BVCI:: BSSGP Virtual Connection Identifier |
| |
| For an explanation of those identifiers and their use in the NS and |
| BSSGP protocols, please see the reelvant 3GPP specifications for NS (TS 08.16) |
| and BSSGP (TS 08.18). |
| |
| In most cases, all above identities belong to different namespaces and |
| must be unique within their respective namespace and within the SGSN |
| they connect to. |
| |
| This means that typically each OsmoPCU has one unique set of NSEI, |
| NSVCI and BVCI in your network. |
| |
| include::gb/ns.adoc[] |
| |
| include::gb/bssgp.adoc[] |
| |
| include::../common/chapters/port_numbers.adoc[] |
| |
| include::../common/chapters/glossary.adoc[] |
| |
| include::../common/chapters/gfdl.adoc[] |