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