101 lines
2.7 KiB
Plaintext
101 lines
2.7 KiB
Plaintext
[[overview]]
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== Overview
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This manual should help you getting started with OsmoMGW. It will cover
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aspects of configuring and running the media gateway.
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[[intro_overview]]
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=== About OsmoMGW
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OsmoMGW is the Osmocom implementation of a media gateway to handle user
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plane (voice) traffic in cellular networks. It can connect and optionally
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transcode RTP voice streams between different network elements such as BTSs
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and external entities like SIP. It is typically co-located with both OsmoBSC
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and OsmoMSC and controlled by them via MGCP, the Media Gateway Control
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Protocol.
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[[fig-bsc]]
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.OsmoMGW used with OsmoBSC
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[graphviz]
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----
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digraph G {
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rankdir = LR;
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OsmoBTS -> OsmoBSC [label="Abis/IP"];
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OsmoBSC -> OsmoMSC [label="3GPP AoIP"];
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OsmoBSC -> OsmoMGW [label="MGCP"];
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OsmoBTS -> OsmoMGW [label="RTP",dir=both];
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OsmoMGW -> OsmoMSC [label="RTP",dir=both];
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{rank=same OsmoBSC OsmoMGW}
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OsmoMGW [color=red];
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}
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----
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[[fig-msc]]
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.OsmoMGW used with OsmoMSC
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[graphviz]
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----
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digraph G {
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rankdir = LR;
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BTS -> BSC [label="Abis"];
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BSC -> OsmoMSC [label="3GPP AoIP"];
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OsmoMSC -> OsmoMGW [label="MGCP"];
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BSC -> OsmoMGW [label="RTP",dir=both];
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OsmoMSC -> OsmoSIP [label="MNCC"];
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OsmoSIP -> PBX [label="SIP Trunk"];
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OsmoMGW -> PBX [label="RTP",dir=both];
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{rank=same OsmoMSC OsmoMGW}
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OsmoSIP [label="osmo-sip-connector"];
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OsmoMGW [color=red];
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hNodeB -> OsmoHNBGW [label="Iuh"];
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OsmoHNBGW -> OsmoMSC [label="IuCS"];
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hNodeB -> OsmoMGW [label="RTP",dir=both];
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}
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----
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=== Software Components
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OsmoMGW contains a variety of different software components, which we’ll
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quickly describe in this section.
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==== MGCP Implementation
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OsmoMGW brings its own MGCP implementation through which OsmoMGW is
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controlled.
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The commands implemented are CRCX, MDCX, DLCX and RSIP. The command AUEP is
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implemented as a stub and will simply respond with OK.
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==== RTP implementation
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Support for IuUP which is used in 3G cells is quite lacking at the moment.
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3G<->3G and 2G<->2G calls should work, but 3G<->2G does not.
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==== Audio transcoder
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Transcoding is currently not supported in OsmoMGW.
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=== Limitations
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Osmux is not yet supported in OsmoMGW.
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At the moment (July 2018), OsmoMGW only implements RTP proxy / RTP bridge
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type endpoints, to each of which two RTP connections can be established.
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We are planning to add endpoint types for:
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- classic E1/T1 timeslots (64kBps alaw/ulaw)
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- classic E1/T1 16k sub-slots with TRAU frames for classic BTS support
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- announcement/playout end-points
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- conference endpoints
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=== Additional resources
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You can find the OsmoMGW issue tracker and wiki online at
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- https://osmocom.org/projects/osmomgw
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- https://osmocom.org/projects/osmomgw/wiki
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RFC 3435 for MGCP is located at
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- https://tools.ietf.org/html/rfc3435
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