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Harald Welte gerrit-no-reply at lists.osmocom.orgHarald Welte has uploaded this change for review. ( https://gerrit.osmocom.org/13763 Change subject: WIP: OsmoGbPROXY user manual ...................................................................... WIP: OsmoGbPROXY user manual Change-Id: I80d4ea016376c59995ccfcd8685c7c0e86745bd2 --- M doc/manuals/Makefile.am A doc/manuals/chapters/gbproxy.adoc A doc/manuals/osmogbproxy-usermanual-docinfo.xml A doc/manuals/osmogbproxy-usermanual.adoc 4 files changed, 212 insertions(+), 1 deletion(-) git pull ssh://gerrit.osmocom.org:29418/osmo-sgsn refs/changes/63/13763/1 diff --git a/doc/manuals/Makefile.am b/doc/manuals/Makefile.am index 00a08c8..f11acb3 100644 --- a/doc/manuals/Makefile.am +++ b/doc/manuals/Makefile.am @@ -1,11 +1,13 @@ EXTRA_DIST = osmosgsn-usermanual.adoc \ osmosgsn-usermanual-docinfo.xml \ osmosgsn-vty-reference.xml \ + osmogbproxy-usermanual.adoc \ + osmogbproxy-usermanual-docinfo.xml \ chapters \ vty if BUILD_MANUALS - ASCIIDOC = osmosgsn-usermanual.adoc + ASCIIDOC = osmosgsn-usermanual.adoc osmogbproxy-usermanual.adoc ASCIIDOC_DEPS = $(srcdir)/chapters/*.adoc include $(OSMO_GSM_MANUALS_DIR)/build/Makefile.asciidoc.inc diff --git a/doc/manuals/chapters/gbproxy.adoc b/doc/manuals/chapters/gbproxy.adoc new file mode 100644 index 0000000..41debe2 --- /dev/null +++ b/doc/manuals/chapters/gbproxy.adoc @@ -0,0 +1,125 @@ +[[chapter_overview]] +== Overview + +== About OsmoGbPROXY + +OsmoGbPROXY is the Osmocom proxy for the 3GPP Gb interface. The Gb +interface is defined by 3GPP as the protocol between the BSS and the +SGSN inside the 2G/2.5G/2.75G packet switched network domain. + +As Osmocom implements a BTS-colocated PCU, there are potentially many +Gb interface connections between all those many PCUs in the network +and the SGSN. This can be cumbersome to configure/maintain at the +SGSN sine. + +OsmoGbPROXY aggregates many PCU-facing Gb connections into one Gb +connection to the SGSN. This is achieved by + +* maintaining sepaate NS-VCs on the PCU side and on the SGSN side +* more or less transparently routing BSSGP peer-to-peer Virtual Circuits + (BVCs) through the proxy +* having some special handling for the signaling BVC (BVCI=0) which is + shared among all the PCUs connected to the proxy + +== Data Model + +=== gbproxy_config + +=== gproxy_peer + +A "peer" is any remote NS-entity that the proxy interacts with. A peer +includes information about: + +* the [unique] NSEI of the peer +* the [unique] BVCI of the peer +* the Routeing Area (RA) of the peer + +=== gbproxy_tlli_state + +One of the (unique) TLLI of any of the subscribers/UEs attached to any of +the BTSs/PCUs served by the proxy. + +=== gbproxy_link_info + +One of the [unique] subscribers/connections that are served through this +proxy. The information includes + +* the TLLI on BSS side +* the TLLI on SGSN side (may be different due to P-TMSI rewriting) +* the NSEI of the SGSN for this link +* a timestamp when we last conversed with this subscriber +* state related to IMSI acquisition +** a temporary queue of stored messages (until IMSI acquisition succeeds) +** N(U) rewriting state (inserting IDENTTIY REQ changes LLC sequence numbers) + +=== gbproxy_match + +A single matching rule against which IMSIs are matched. The matching rule +is expressed as regular expression. There can be one such matching rule for +each + +* routing between two different SGSNs, see below +* patching of messages (e.g. APN, PLMN) + + +== Advanced Features + +=== PLMN patching + +This feature permits to modify the PLMN inside any BSSGP messages +containing the Routing Area ID (RAID). + +The configured core-mcc and core-mnc will be used towards the SGSN, +irrespective of which MCC/MNC the PCU is using/reporting on Gb. + +=== APN patching + +This will transparently re-write the APN name inside SM ACTIVATE PDP +REQUEST messages on the way from the MS to the SGSN. The patching is +performed based on matching on the IMSI of the subscriber. + +The configured core-apn will be used towards the SGSN, irrespective +of which APN the MS is requesting in its Layer3 signaling. + +APN patching can only be performed if no GPRS encryption is enabled in +the network! + +APN patching is useful in case a valid APN cannot reliably be +provisioned via other means, such as via the SIM Card, OTA-DM or via +CAMEL rewriting in the SGSN. + +=== P-TMSI patching + +This feature transparently rewrite the P-TMSI between MS and SGSN. This +is required when using the Secondary SGSN support, as both SGSNs could +allocate overlapping TMSIs and we must make sure they're unique across +both SGSNs. + +P-TMSI patching is required by (and hence automatically enablede if +secondary SGSN support is enabled. + +P-TMSI patching can only be performed if no GPRS encryption is enabled in +the network! + +=== IMSI Acquisition + +This is a special feature where the proxy will by itself inject GMM IDENTITY +REQUEST messages for the IMSI into the downlink BSSGP traffic in order +to establish the IMSI of subscribers for which it is not otherwise known + +IMSI acquisition is automatically enabled if secondary SGSN support is +enabled. + +=== Secondary SGSN Support + +This allows the proxy to connect not only to one SGSN, but to two +different SGSNs. IMSI matching rules are applied to determine which of +the SGSNs is to be used for traffic of this subscriber. + +One possible use case of this feature is to have a "local break-out" for +subscribers who are native to this network (and hence save +latencies/overhead of back-hauling all related traffic via the +SGSN+GGSN) while at the same time maintaining the classic behavior for +inbound roaming subscribers, where the roaming agreements mandate that +data traffic is brought back to the GGSN in the HPLMN via the SGSN of +the VPLMN. diff --git a/doc/manuals/osmogbproxy-usermanual-docinfo.xml b/doc/manuals/osmogbproxy-usermanual-docinfo.xml new file mode 100644 index 0000000..29bb2aa --- /dev/null +++ b/doc/manuals/osmogbproxy-usermanual-docinfo.xml @@ -0,0 +1,46 @@ +<revhistory> + <revision> + <revnumber>1</revnumber> + <date>March 21, 2019</date> + <authorinitials>HW</authorinitials> + <revremark> + Initial version. + </revremark> + </revision> +</revhistory> + +<authorgroup> + <author> + <firstname>Harald</firstname> + <surname>Welte</surname> + <email>hwelte at sysmocom.de</email> + <authorinitials>HW</authorinitials> + <affiliation> + <shortaffil>sysmocom</shortaffil> + <orgname>sysmocom - s.f.m.c. GmbH</orgname> + <jobtitle>Managing Director</jobtitle> + </affiliation> + </author> +</authorgroup> + +<copyright> + <year>2013-2019</year> + <holder>sysmocom - s.f.m.c. GmbH</holder> +</copyright> + +<legalnotice> + <para> + Permission is granted to copy, distribute and/or modify this + document under the terms of the GNU Free Documentation License, + Version 1.3 or any later version published by the Free Software + Foundation; with no Invariant Sections, no Front-Cover Texts, + and no Back-Cover Texts. A copy of the license is included in + the section entitled "GNU Free Documentation License". + </para> + <para> + The Asciidoc source code of this manual can be found at + <ulink url="https://git.osmocom.org/osmo-sgsn/doc/"> + https://git.osmocom.org/osmo-sgsn/doc/ + </ulink> + </para> +</legalnotice> diff --git a/doc/manuals/osmogbproxy-usermanual.adoc b/doc/manuals/osmogbproxy-usermanual.adoc new file mode 100644 index 0000000..0b5bed9 --- /dev/null +++ b/doc/manuals/osmogbproxy-usermanual.adoc @@ -0,0 +1,38 @@ +:gfdl-enabled: + +OsmoGbPROXY User Manual +==================== +Harald Welte <hwelte at sysmocom.de> + + +include::./common/chapters/preface.adoc[] + +//include::{srcdir}/chapters/overview.adoc[] + +//include::{srcdir}/chapters/running.adoc[] + +//include::{srcdir}/chapters/control.adoc[] + +include::./common/chapters/vty.adoc[] + +include::./common/chapters/logging.adoc[] + +//include::{srcdir}/chapters/configuration.adoc[] + +include::./common/chapters/gb.adoc[] + +include::./common/chapters/control_if.adoc[] + +//include::./common/chapters/oap.adoc[] + +//include::./common/chapters/gsup.adoc[] + +//include::{srcdir}/chapters/counters.adoc[] + +include::./common/chapters/port_numbers.adoc[] + +include::./common/chapters/bibliography.adoc[] + +include::./common/chapters/glossary.adoc[] + +include::./common/chapters/gfdl.adoc[] -- To view, visit https://gerrit.osmocom.org/13763 To unsubscribe, or for help writing mail filters, visit https://gerrit.osmocom.org/settings Gerrit-Project: osmo-sgsn Gerrit-Branch: master Gerrit-MessageType: newchange Gerrit-Change-Id: I80d4ea016376c59995ccfcd8685c7c0e86745bd2 Gerrit-Change-Number: 13763 Gerrit-PatchSet: 1 Gerrit-Owner: Harald Welte <laforge at gnumonks.org> -------------- next part -------------- An HTML attachment was scrubbed... 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