From 2283831b647bfa04094115ef293081c8ee250d0b Mon Sep 17 00:00:00 2001 From: Harald Welte Date: Wed, 19 Jul 2017 19:17:18 +0200 Subject: [PATCH] update osmo-bts-virtual documentation, now that code is merged Change-Id: Icd8706d29ca0e96cb89b7736dbb62f9ce159382d --- doc/manuals/chapters/bts-models.adoc | 53 +++++++++++++++++++++------- 1 file changed, 41 insertions(+), 12 deletions(-) diff --git a/doc/manuals/chapters/bts-models.adoc b/doc/manuals/chapters/bts-models.adoc index 40a86e2eb..5e5100928 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 +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)