From fca59bea770346cf1c1f9b0e00cb48a61b44a8f3 Mon Sep 17 00:00:00 2001
From: Harald Welte <laforge@gnumonks.org>
Date: Sun, 25 Oct 2015 21:00:20 +0100
Subject: import of old now defunct presentation slides svn repo

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 2011/gsm-ensa2011/section-openbsc.tex | 208 ++++++++++++++++++++++++++++++++++
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 create mode 100644 2011/gsm-ensa2011/section-openbsc.tex

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+\section{OpenBSC}
+
+\subsection{OpenBSC Introduction}
+
+\begin{frame}{OpenBSC software}
+OpenBSC is a Open Source implementation of (not only) the BSC features
+of a GSM network.
+\begin{itemize}
+	\item Support A-bis interface over E1 and IP
+	\item Support for BTS vendor/model is modular, currently Siemens BS-11 and ip.access nanoBTS
+	\item Multiple BTS models/vendors can be mixed!
+	\item Can work as a {\em pure BSC} or as a full {\em network in a box}
+	\item Supports mobility management, authentication, intra-BSC hand-over, SMS, voice calls (FR/EFR/AMR)
+	\item GPRS + EDGE support if combined with OsmoSGSN and OpenGGSN
+\end{itemize}
+\end{frame}
+
+\begin{frame}{OpenBSC}
+\begin{itemize}
+	\item Supports Siemens BS-11 BTS (E1) and ip.access nanoBTS (IP based)
+	\item Has classic 2G signalling, voice and SMS support
+	\item Implements various GSM protocols like
+	\begin{itemize}
+		\item A-bis RSL (TS 08.58) and OML (TS 12.21)
+		\item TS 04.08 Radio Resource, Mobility Management, Call Control
+		\item TS 04.11 Short Message Service
+	\end{itemize}
+	\item Telnet console with Cisco-style interface
+\end{itemize}
+\end{frame}
+
+\begin{frame}{OpenBSC software architecture}
+\begin{itemize}
+	\item Implemented in pure C, similarities to Linux kernel
+	\begin{itemize}
+		\item Linked List handling, Timer API, coding style
+	\end{itemize}
+	\item Single-threaded event-loop / state machine design
+	\item Telnet based command line interface {\em Cisco-style}
+	\item Input driver abstraction (mISDN, Abis-over-IP)
+\end{itemize}
+\end{frame}
+
+\begin{frame}{OpenBSC: GSM network protocols}{The A-bis interface}
+  \begin{description}[Layer 4+]
+    \item[Layer 1] Typically E1 line, TS 08.54
+    \item[Layer 2] A variant of ISDN LAPD with fixed TEI's, TS 08.56
+    \item[Layer 3] OML (Organization and Maintenance Layer, TS 12.21)
+    \item[Layer 3] RSL (Radio Signalling Link, TS 08.58)
+    \item[Layer 4+] transparent messages that are sent to the MS via Um
+  \end{description}
+\end{frame}
+
+\begin{frame}{OpenBSC: How it all started}
+\begin{itemize}
+	\item In 2006, I bought a Siemens BS-11 microBTS on eBay
+	\begin{itemize}
+		\item This is GSM900 BTS with 2 TRX at 2W output power (each)
+		\item A 48kg monster with attached antenna
+		\item 200W power consumption, passive cooling
+		\item E1 physical interface
+	\end{itemize}
+	\item I didn't have much time at the time (day job at Openmoko)
+	\item Started to read up on GSM specs whenever I could
+	\item Bought a HFC-E1 based PCI E1 controller, has mISDN kernel support
+	\item Found somebody in the GSM industry who provided protocol traces
+\end{itemize}
+\end{frame}
+
+\begin{frame}{OpenBSC: Timeline}
+\begin{itemize}
+	\item November 2008: I started the development of OpenBSC
+	\item December 2008: we did a first demo at 25C3
+	\item January 2009: we had full voice call support
+	\item Q1/2009: Add support for ip.access nanoBTS
+	\item June 2009: I started with actual security related stuff
+	\item August 2009: We had the first field test with 2BTS and > 860 phones
+	\item Q1/2010: The first 25 OpenBSC instances running in a commercial network
+\end{itemize}
+\end{frame}
+
+\begin{frame}{OpenBSC: Field Test at HAR2009}
+\begin{figure}[h]
+\subfigure{\includegraphics[width=5cm]{bts_tree_full.jpg}}
+\subfigure{\includegraphics[width=5cm]{openbsc_host.jpg}}
+\end{figure}
+\end{frame}
+
+
+\subsection{OpenBSC Network In The Box}
+
+\begin{frame}{OpenBSC in NITB mode}{Network In a Box Mode}
+The {\tt osmo-nitb} program
+\begin{itemize}
+	\item implements the A-bis interface towards any number of BTS
+	\item provides most typical features of a GSM network in one software
+	\item no need for MSC, AuC, HLR, VLR, EIR, ...
+	\begin{itemize}
+		\item HLR/VLR as SQLite3 table
+		\item Authentication + Ciphering support
+		\item GSM voice calls, MO/MT SMS
+		\item Hand-over between all BTS
+		\item Multiple Location Areas within one BSC
+	\end{itemize}
+\end{itemize}
+\end{frame}
+
+\begin{frame}{OpenBSC NITB features}
+OpenBSC NITB features
+\begin{itemize}
+	\item Run a small GSM network with 1-n BTS and OpenBSC
+	\item No need for MSC/HLR/AUC/...
+	\item No need for your own SIM cards (unless crypto/auth rqd)
+	\item Establish signalling and voice channels 
+	\item Make incoming and outgoing voice calls between phones
+	\item Send/receive SMS between phones
+	\item Connect to ISDN PBX or public ISDN via Linux Call Router
+\end{itemize}
+\end{frame}
+
+\begin{frame}{OpenBSC in NITB mode}{Network In a Box Mode}
+The {\tt osmo-nitb} program
+\begin{itemize}
+	\item does not implement any other GSM interfaces apart from A-bis
+	\item no SS7 / TCAP / MAP based protocols
+	\item no integration (roaming) with existing traditional GSM networks
+	\item wired telephony interfacing with ISDN PBX {\tt lcr} (Linux Call Router)
+	\item Has been tested with up to 800 subscribers on 5 BTS
+	\item Intended for R\&D use or private PBX systems
+\end{itemize}
+\end{frame}
+
+\begin{frame}{OpenBSC LCR integration}{Interfacing with wired telephony}
+OpenBSC (NITB mode) can be linked into Linux Call Router ({\tt lcr})
+\begin{itemize}
+	\item OpenBSC is compiled as libbsc.a
+	\item libbsc.a includes full OpenBSC NITB mod code
+	\item linking the library into {\tt lcr} results in GSM {\em line interfaces} to become available inside {\tt lcr}
+	\item OpenBSC no longer takes care of call control, but simply hands everything off to {\tt lcr}
+	\item Dialling plan, etc. is now configure in {\tt lcr} like for any other wired phones
+\end{itemize}
+\end{frame}
+
+\subsection{OpenBSC BSC-only mode}
+
+\begin{frame}{OpenBSC in BSC-only mode}
+The {\tt osmo-bsc} program
+\begin{itemize}
+	\item behaves like a classic GSM BSC
+	\item uses SCCP-Lite (ip.access multipex) to any SoftMSC like ADC
+	\item used in production/commercial deployments (~ 75 BSCs)
+	\item mainly intended to replace proprietary BSC in traditional GSM networks
+\end{itemize}
+\end{frame}
+
+%\begin{frame}<handout:0>{OpenBSC}
+%        Demonstration
+%\end{frame}
+
+\subsection{OpenBSC GPRS support}
+
+\begin{frame}{GPRS and OpenBSC}
+\begin{itemize}
+	\item The BSC doesn't really do anything related to GPRS
+	\item GPRS implemented in separate SGSN and GGSN nodes
+	\item GPRS uses its own Gb interface to RAN, independent of A-bis
+	\item OpenBSC can configure the nanoBTS for GPRS+EDGE support via OML
+	\item Actual SGSN and GGSN implemented as OsmoSGSN and OpenGGSN programs
+\end{itemize}
+\end{frame}
+
+\begin{frame}{OsmoSGSN}
+The Osmocom SGSN program implements
+\begin{itemize}
+	\item basic/minimal SGSN functionality
+	\item the Gb interface (NS/BSSGP/LLC/SNDCP)
+	\item mobility management, session management
+\end{itemize}
+It's a work in progress, many missing features
+\begin{itemize}
+	\item no HLR integration yet
+	\item no paging coordination with MSC/BSC
+	\item no encryption support yet
+\end{itemize}
+\end{frame}
+
+\begin{frame}{OpenGGSN}
+\begin{itemize}
+	\item GPL licensed Linux program implementing GGSN node
+	\item Implements GTP-U protocol between SGSN and GGSN
+	\item User-configurable range/pool of IPv4 addresses for MS
+	\item Uses {\tt tun} device for terminating IP tunnel from MS
+	\item provides GTP implementation as libgtp
+	\item Experimental patches for IPv6 support
+\end{itemize}
+\end{frame}
+
+%\begin{frame}<handout:0>{OpenBSC + OpenGGSN + OsmoSGSN}
+%        Demonstration
+%\end{frame}
+
+\begin{frame}{OpenBSC and OsmoSGSN based network}
+\begin{figure}[h]
+\includegraphics[width=10cm]{osmosgsn.png}
+\end{figure}
+\end{frame}
+
+% FIXME: include slide showing full OpenBSC+OsmoSGSN+OpenGGSN network
-- 
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