diff options
authorHarald Welte <laforge@gnumonks.org>2017-07-19 19:17:18 +0200
committerNeels Hofmeyr <neels@hofmeyr.de>2018-11-27 17:54:20 +0100
commit2283831b647bfa04094115ef293081c8ee250d0b (patch)
parenteaef0af3a28ae5451a89d86233c92d10dec1ca24 (diff)
update osmo-bts-virtual documentation, now that code is merged
1 files changed, 41 insertions, 12 deletions
diff --git a/doc/manuals/chapters/bts-models.adoc b/doc/manuals/chapters/bts-models.adoc
index 40a86e2e..5e510092 100644
--- a/doc/manuals/chapters/bts-models.adoc
+++ b/doc/manuals/chapters/bts-models.adoc
@@ -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
+=== `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 virtual Um
+downlink messages towards the MS (default: GSMTAP 4729).
+===== `virtual-um ms-multicast-group GROUP`
+Configure the IP multicast group used for sending virtual
+Um downlink messages towards the MS (default:
+===== `virtual-um bts-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 receiving virtual Um
+uplink messages from the MS (default: GSMTAP 4729).
-===== `virtual-um multicast-group GROUP`
+===== `virtual-um bts-multicast-group GROUP`
-Configure the IP multicast group used for sending/receiving the virtual
-Um interface messages.
+Configure the IP multicast group used for receiving virtual
+Um uplink messages from the MS (default: