add slides on Osmocom GSUP protocol

2016/osmocom_gsup/osmocom_gsup.adoc

@@ -0,0 +1,47 @@
+Osmocom GSUP Protocol
+=====================
+Harald Welte
+:copyright: Harald Welte (Liense: CC-BY-SA)
+:backend: slidy
+:max-width: 45em
+
+== GSUP basics
+
+* very much simplified protocol for handling procedures betewen *SGSN* and *HLR*
+* procedures / primitives similar to those carried by MAP
+** without the complexity of ASN.1
+** without the complexity of a TCAP/SCCP protocol stack underneath
+** without the nasty segmented MAP due to limited MSU size in SS7
+
+== GSUP history
+
+* originally developed for *SGSN* <-> *HLR* interface
+* originally called 'GPRS Subscriber Update Protocol'
+* implemented in OsmoSGSN (but no counter-part in Osmocom git repos?)
+
+== GSUP extension for 3G
+
+* Iu-PS was added to OsmoSGSN, requiring UMTS AKA
+* GSUP authentication triplets extended to quintuples
+* GSUP SendAuthInfo extended with RAND (for AKA re-sync)
+* *osmo-gsup-hlr* as minimalistic HLR+AUC side implementation
+
+== GSUP extension circuit-switched
+
+* HLR must know if request is from CS(MSC) or PS(SGSN)
+** introduce OSMO_GSUP_CN_DOMAIN_IE to differentiate CS/PS
+* VLR must have ability to inform HLR of AUTH FAIL
+** introduce OSMO_GSUP_MSGT_AUTH_FAIL_REPORT
+
+== Misc GSUP changes in 2016
+
+* GSUP protocol definition and message encoder/decoder move to
+  libosmocore (gprs_gsup_* -> osmo_gsup_* rename)
+* Doxygen documentation snippets added
+* GSUP documentation moved to asciidoc and into osmo-gsm-manuals.git
+
+include::gsup.adoc[]
+
+== The End
+
+Questions?