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laforge gerrit-no-reply at lists.osmocom.orglaforge has submitted this change. ( https://gerrit.osmocom.org/c/osmo-gsm-manuals/+/17502 ) Change subject: add common/chapters/cs7-config ...................................................................... add common/chapters/cs7-config This will be used by the manuals of osmo-bsc, osmo-hnbgw, osmo-msc, osmo-sgsn. Related: OS#2767 Change-Id: Ia2508d4c7b0fef9cdc57e7e122799a480e340bf7 --- A common/chapters/cs7-config.adoc 1 file changed, 293 insertions(+), 0 deletions(-) Approvals: Jenkins Builder: Verified laforge: Looks good to me, approved diff --git a/common/chapters/cs7-config.adoc b/common/chapters/cs7-config.adoc new file mode 100644 index 0000000..c489883 --- /dev/null +++ b/common/chapters/cs7-config.adoc @@ -0,0 +1,293 @@ +[[cs7_config]] +== Configure SCCP/M3UA + +All CNI programs using SCCP/M3UA act as M3UA ASP role and SCTP client, +expecting to connect to a Signalling Gateway (STP/SG) implementing the M3UA +SG role as SCTP server. The STP/SG then routes M3UA messages between its +ASPs, typically by point-codes. + +In an all-Osmocom CNI, the typical simple/minimal usage is: + +- OsmoSTP acts as the STP/SG (server role) and routes between the ASP, +- All other Osmocom CNI programs act as SCTP client and provide ASP + implementations. + +For example, in an all-Osmocom minimal setup, + +- OsmoMSC contacts an OsmoSTP and subscribes its point-code 0.23.1; +- then OsmoBSC also contacts the same OsmoSTP, subscribes with its own + point-code 1.23.3. +- Using these established links, OsmoBSC initiates an A-interface link by + directing a BSSAP RESET message to the MSC's point-code 0.23.1, +- and the RESET ACK response from the MSC is routed back to the BSC's + point-code 1.23.3. + +The details of SCCP/M3UA are configured in the 'cs7' section of the VTY +configuration. + +Osmocom programs automatically configure missing SCCP/M3UA configuration, by +assuming sane defaults for small/minimal all-Osmocom installations, which may +not be what you want in larger networks integrating with non-Osmocom core +network elements. + +If no explicit `routing-key` is set, it may be determined at runtime by +negotiation with OsmoSTP -- see OsmoSTP manual chapter "Osmocom M3UA Routing +Key Management Extensions", regarding config option `accept-asp-connections +dynamic-permitted`. + +The complete active configuration of an Osmocom program can be obtained by the +VTY command `show cs7 config` (the usual `show running-config` omits +automatically configured items). Here is an example of OsmoMSC's default +configuration: + +---- +OsmoMSC> show cs7 config +cs7 instance 0 + point-code 0.23.1 + asp asp-clnt-OsmoMSC-A-Iu 2905 0 m3ua + remote-ip 127.0.0.1 + sctp-role client + as as-clnt-OsmoMSC-A-Iu m3ua + asp asp-clnt-OsmoMSC-A-Iu + routing-key 2 0.23.1 +---- + +At the time of writing, SCCP/M3UA links involving Osmocom program are: + +- A-interface: OsmoBSC to OsmoMSC +- IuCS-interface: OsmoHNBGW to OsmoMSC +- IuPS-interface: OsmoHNBGW to OsmoSGSN + +=== Connect to STP Instance + +By default, an STP instance is assumed to listen on the default M3UA port +(2905) on the local host (127.0.0.1). + +Establishing an SCCP/M3UA link towards a remote STP instance can be configured +as: + +---- +cs7 instance 0 + asp my-asp 2905 0 m3ua + # IP address of the remote STP: + remote-ip 10.23.24.1 + # optional: local bind to a specific IP + local-ip 10.9.8.7 +---- + +Be aware that such an `asp` needs to be linked to an `as`, see <<as_and_asp>>. + +=== Local Point-Code + +Each CNI program on an SCCP/M3UA link typically has a local point-code, +configurable by: + +---- +cs7 instance 0 + point-code 7.65.4 +---- + +If an explicit routing context is configured, this point-code is repeated in +the `routing-key` configuration: + +---- +cs7 instance 0 + point-code 0.23.1 + as my-as m3ua + routing-key 2 0.23.1 +---- + +See also <<point_code_format>>. + +=== Remote Point-Code + +Programs establishing communication across SCCP links need a remote SCCP +address, typically by point-code, to contact. + +For example, + +- OsmoBSC needs to know the MSC's point-code, to be able to establish the A-interface. +- OsmoHNBGW needs to know the MSC's point-code, to be able to establish the IuCS-interface. +- OsmoHNBGW needs to know the SGSN's point-code, to be able to establish the IuPS-interface. + +To maintain remote SCCP addresses, each `cs7` instance maintains an SCCP address book: + +---- +cs7 instance 0 + sccp-address remote-pc-example + point-code 1.23.1 +---- + +This address book entry on its own has no effect. It is typically referenced by +specific configuration items depending on the individual programs. + +Examples: + +- An OsmoBSC configures the MSC's remote SCCP address: + +---- +cs7 instance 0 + sccp-address my-remote-msc + point-code 1.23.1 +msc 0 + msc-addr my-remote-msc +---- + +- An HNBGW configures both the remote MSC's and SGSN's SCCP addresses: + +---- +cs7 instance 0 + sccp-address my-msc + point-code 0.23.1 + sccp-address my-sgsn + point-code 0.23.2 +hnbgw + iucs + remote-addr my-msc + iups + remote-addr my-sgsn +---- + +Besides a point-code, an SCCP address can have several routing indicators: + +- PC: routing by point-code is the default for Osmocom. +- GT: routing by Global Title is configurable by `routing-indicator GT`. +- IP: routing by IP address is configurable by `routing-indicator IP`. + +In OsmoSTP, only routing by point-code is currently implemented. + +[[point_code_format]] +=== Point-Code Format + +Point-codes can be represented in various formats. For details, see OsmoSTP +manual, chapter "Point Codes". + +By default, Osmocom uses a point-code representation of 3.8.3, i.e. first digit +of 3 bit, second digit of 8 bit, and third digit of 3 bit. + +---- +cs7 instance 0 + point-code format 3 8 3 + point-code 0.23.1 +---- + +Often, point-codes are also represented as a single decimal number: + +---- +cs7 instance 0 + point-code format 24 + point-code 185 +---- + +It is also possible to use a dash as delimiter. + +---- +cs7 instance 0 + point-code delimiter dash + point-code 0-23-1 +---- + + +[[as_and_asp]] +=== AS and ASP + +Each CNI program needs at least one Application Server `as` and one Application +Server Process `asp` configured on its `cs7` to be able to communicate on +SCCP/M3UA. An `asp` needs to be part of at least one `as`. For details, see the +OsmoSTP manual, chapters "Application Server" and "Application Server Process". + +In Osmocom's `cs7`, any amount of `as` and `asp` can be configured by name, and +an `as` references the `asp` entries belonging to it by their names. + +In a simple/minimal Osmocom setup, an Osmocom CNI program would have exactly +one `as` with one `asp`. + +For example: + +---- +cs7 instance 0 + asp my-asp 2905 0 m3ua + # where to reach the STP: + remote-ip 127.0.0.1 + sctp-role client + as my-as m3ua + asp my-asp +---- + +In Osmocom CNI programs, it is possible to omit the `as` and/or `asp` entries, +which the program will then attempt to configure automatically. + +When configuring both `as` and `asp` manually, make sure to link them by name. +For example, the following configuration will *fail*, because `as` and `asp` +are not linked: + +---- +cs7 instance 0 + asp my-asp 2905 0 m3ua + remote-ip 127.0.0.1 + as my-as m3ua + routing-key 2 0.23.1 +---- + +To *fix* above config, link the `asp` to an `as` by adding `asp my-asp`: + +---- +cs7 instance 0 + asp my-asp 2905 0 m3ua + remote-ip 127.0.0.1 + as my-as m3ua + asp my-asp + routing-key 2 0.23.1 +---- + +=== Subsystem Number (SSN) + +Osmocom CNI programs typically route SCCP/M3UA messages by PC+SSN: each ASP, +having a given SCCP address, receives messages for one or more specific +subsystems, identified by a Subsystem Number (SSN). + +For example, the A-interface between BSC and MSC uses SSN = BSSAP (254). In +Osmocom programs, SSNs do not need to be configured; they implicitly, naturally +relate to the interfaces that a program implements. + +For example, OsmoBSC takes the configured remote MSC's SCCP address and adds +the SSN = BSSAP to it in order to contact the MSC's A-interface. To receive +A-interface messages from the MSC, OsmoBSC subscribes a local user for this SSN +on the ASP. + +=== Routing Context / Routing Key + +In SCCP/M3UA, messages can be routed by various Routing Indicators (PC+SSN, PC, +GT, ...). Osmocom CNI programs typically use PC+SSN as Routing Indicator. + +On the SG (for example OsmoSTP), each ASP's distinct Routing Indicator needs to +be indexed by a distinct Routing Context (a simple index number scoped per SG), +to forward M3UA to the correct peer. + +The Osmocom SG implementation employs Routing Key Management (RKM, see OsmoSTP +manual) to automatically determine a distinct Routing Context index for each +connected ASP. Routing Contexts can also be configured manually -- some +non-Osmocom SG implementations require this. + +Each Routing Context is associated with a Routing Indicator and address; this +association is called a Routing Key. + +For example, to configure an OsmoBSC with a local point-code of 1.23.3 to +receive M3UA with Routing Context of 2 and RI=PC: + +---- +cs7 instance 0 + point-code 1.23.3 + as my-as m3ua + routing-key 2 1.23.3 +---- + +Osmocom programs so far implement Routing Keys by Destination Point Code (DPC), +plus optional Subsystem Number (SSN) and/or Service Indicator (SI): + +---- +routing-key RCONTEXT DPC +routing-key RCONTEXT DPC si (aal2|bicc|b-isup|h248|isup|sat-isup|sccp|tup) +routing-key RCONTEXT DPC ssn SSN +routing-key RCONTEXT DPC si (aal2|bicc|b-isup|h248|isup|sat-isup|sccp|tup) ssn SSN +---- -- To view, visit https://gerrit.osmocom.org/c/osmo-gsm-manuals/+/17502 To unsubscribe, or for help writing mail filters, visit https://gerrit.osmocom.org/settings Gerrit-Project: osmo-gsm-manuals Gerrit-Branch: master Gerrit-Change-Id: Ia2508d4c7b0fef9cdc57e7e122799a480e340bf7 Gerrit-Change-Number: 17502 Gerrit-PatchSet: 2 Gerrit-Owner: neels <nhofmeyr at sysmocom.de> Gerrit-Reviewer: Jenkins Builder Gerrit-Reviewer: laforge <laforge at osmocom.org> Gerrit-Reviewer: neels <nhofmeyr at sysmocom.de> Gerrit-Reviewer: pespin <pespin at sysmocom.de> Gerrit-MessageType: merged -------------- next part -------------- An HTML attachment was scrubbed... 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