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update osmo-bts-virtual documentation, now that code is merged 

Change-Id: Icd8706d29ca0e96cb89b7736dbb62f9ce159382d
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Harald Welte 2017-07-19 19:17:18 +02:00 committed by Neels Hofmeyr
parent eaef0af3a2
commit 2283831b64
1 changed files with 41 additions and 12 deletions
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53
doc/manuals/chapters/bts-models.adoc
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@ -381,13 +381,32 @@ This is a special BTS model used for research, simulation and testing.
Rather than communicating over a wireless RF interface, the GSM Um
messages are encapsulated over GSMTAP/UDP/IP.
At the time of writing, this functionality is not fully completed. It
is the idea to adopt the OsmocomBB MS-side GSM implementation to
interface with this virtual Um interface, so that many instances of
virtual MS can connect to some instances of OsmoBTS, testing MS, BTS,
BSC and core network functionality.
The Virtual Um interface (i.e. virtual radio layer) between OsmoBTS and
OsmocomBB allows us to run a complete GSM network with 1-N BTSs and 1-M
MSs without any actual radio hardware, which is of course excellent for
all kinds of testing scenarios.
=== `osmo-bts-trx` specific VTY commands
The Virtual Um layer is based on sending L2 frames (blocks) encapsulated
via GSMTAP UDP multicast packets. There are two separate multicast
groups, one for uplink and one for downlink. The multicast nature
simulates the shared medium and enables any simulated phone to receive
the signal from multiple BTSs via the downlink multicast group.
In OsmoBTS, this is implemented via the `osmo-bts-virtual` BTS model.
Setting up OsmoBTS in its `osmo-bts-virtual` flavor isn't really much
different from setting it up with real hardware. The amount of required
configuration at the BTS configuration file is (as always) very minimal,
as in the GSM network architecture provides almost all relevant
configuration to the BTS from the BSC.
An example configuratin file is provided as part of the osmo-bts source
code: `doc/examples/virtual/osmobts-virtual.cfg`
For more information see
http://osmocom.org/projects/cellular-infrastructure/wiki/Virtual_Um
=== `osmo-bts-virtual` specific VTY commands
For a auto-generated complete syntax reference of the VTY commands,
please see the associated _OsmoBTS VTY reference manual_
@ -401,12 +420,22 @@ commands.
Configure the network device used for sending/receiving the virtual Um
interface messages (e.g. `eth0`).
===== `virtual-um udp-port <0-65535>`
===== `virtual-um ms-udp-port <0-65535>`
Configure the UDP port used for sending/receiving the virtual Um
interface messages (default: GSMTAP 2775).
Configure the UDP port used for sending virtual Um
downlink messages towards the MS (default: GSMTAP 4729).
===== `virtual-um multicast-group GROUP`
===== `virtual-um ms-multicast-group GROUP`
Configure the IP multicast group used for sending/receiving the virtual
Um interface messages.
Configure the IP multicast group used for sending virtual
Um downlink messages towards the MS (default: 239.193.23.1)
===== `virtual-um bts-udp-port <0-65535>`
Configure the UDP port used for receiving virtual Um
uplink messages from the MS (default: GSMTAP 4729).
===== `virtual-um bts-multicast-group GROUP`
Configure the IP multicast group used for receiving virtual
Um uplink messages from the MS (default: 239.193.23.2)