Field Name	Default	Range	Description
`USER_SAP`	None	0-`(MAX_USERS`-1)	Marks start of a User SAP definition; User SAP numbers start at 0 and are numbered sequentially up to `MAX_USERS`-1
`SWITCH_TYPE`	`ANSI92`	`ITU88, ITU92, ANSI88, ANSI 92`	Protocol variant employed on this user SAP
`BACKUP_PC`	None	Use "dotted" notation, e.g., 2.45.76 or hex number, e.g., 0x101.	Point code where this subsystem is backed up.
`CONC_PC`	None	Use "dotted" notation, e.g., 2.45.76 or hex number, e.g., 0x101.	Concerned point code to be notified of changes in the availability of this application; up to eight `CONC_PC` entries (on separate lines) are allowed per User SAP.
`ADDR_MASK`	FFF...F	N/A	ASCII string describing which digits of global title to match on when performing global title translation (see note 1).
`MAX_HOPS`	10	1-15	Hop count value to be used on outgoing SCCP messages from this SAP.
`END`			REQUIRED - denotes end of section.

Field Name	Default	Range	Description
`NSAP`	None	0-(`MAX_NSAPS`-1)	Marks start of a Network SAP definition; NSAP numbers start at 0 and are numbered sequentially up to `MAX_NSAPS`-1 (this must match a NSAP number defined in the MTP 3 configuration).
`SWITCH_TYPE`	`ANSI`	`ITU, ANSI`	Protocol variant employed on this NSAP
`SSF`	`NATL (ANSI), INTL (ITU)`	`INTERNATIONAL \| ITL, SPARE, NATIONAL \| NATL, RESERVED \| RES`	The value to be used in the sub-service field for this network;
`DPC`	None	Use "dotted" notation, e.g., 2.45.76 or hex number, e.g., 0x101	REQUIRED - Point code of this node on this network interface.
`DPC_LEN`	24 (ANSI \| ITU) 14 (ITU)	14 \| 24	Point code length employed on this network
`MSG_LEN`	256	32-1500	Maximum length of a message passed to MTP 3 on this SAP.
`TXQ_THRESH`	20	0-32766	Maximum number of messages to queue to MTP 3 (i.e., when flow control is on) before discarding.
`ADDR_MASK`	FFF...F	N/A	Ascii string describing which digits of global title to match on when performing global title translation (See note below and also note from User SAP section).
`MAX_HOPS`	10	1-15	Hop count value to be used when returning undeliverable incoming messages back to the source of the message.
`END`			REQUIRED - denotes end of section.

Field Name	Default	Range	Description
`ADDRESS`	None	N/A	Incoming global title string, ascii (ASCII digits; i.e. "0"-"9"
`REPLACE_GLT`	`FALSE`	`TRUE \| FALSE`	If `TRUE`, replace translated global title in outgoing message If `FALSE`, incoming global title and translated point code & subsystem are copied to outgoing message.
`SWITCH_TYPE`	`ANSI`	`ITU \| ANSI`	Format of this address
`NI_IND`	`NAT`	`NATIONAL \| NAT, INTERNATIONAL \| INTL`	National/International indicator
`ROUTING_IND`	`PC_SSN`	`PC_SSN, GLT`	Routing indicator for translated address, either "route by PC & SSN" or "route by global title"
`SSN`	None	0-255	Translated subsystem number (required for `GT_FORMAT` 0)
`DPC`	None	Use "dotted" notation, e.g., 2.45.76 or hex number, e.g., 0x101	Translated destination point code (required for `GT_FORMAT` 0)
`GT_FORMAT`	0	0...4	Defines structure of outgoing global title. Used only when `REPLACE_GLT` parameter is `TRUE`.
		0	No global title translation.
		1	ANSI: Outgoing global title includes translation type, numbering plan, and encoding scheme. ITU: Outgoing global title includes nature of address indicator.
		2	ANSI and ITU: Outgoing global title includes translation type only.
		3	ITU only: Outgoing global title includes translation type, numbering plan, and encoding scheme.
		4	ITU only: Outgoing global title includes translation type, numbering plan, encoding scheme, and nature of address indicator.
`GL_TITLE`	None	N/A	Outgoing global title string (ASCII digits; i.e. "0"-"9"). Used only when `REPLACE_GLT` parameter is `TRUE`
`TRANS_TYPE`	0	0-255	Outgoing global title translation type, used only when `REPLACE_GLT` parameter is `TRUE`
`NAT_ADDR`	3	0-4	Outgoing global title nature of address indicator (ITU only). Used only when `REPLACE_GLT` parameter is `TRUE`
`NUM_PLAN`	1	0-15	Outgoing global title numbering plan (ISDN Numbering Plan). Used only when `REPLACE_GLT` parameter is `TRUE`
`END`			REQUIRED - denotes end of section.

(Page 1 of 1 in this chapter) Version

Chapter 7

SS7 SCCP Configuration

7.1 Introduction to the SCCP Layer

7.2 The SCCP Configuration

7.3 Sample SCCP Configuration File

7.4 Using Default Routing

: 7.4.1 Introduction
: 7.4.2 Enabling Default Routing
: 7.4.3 Impact of Default Routing on SCCP Message Routing
: 7.4.4 Impact of Default Routing on SCCP Management
: 7.4.5 SCCP Limitations When Default Routing is Enabled

7.5 Configuring Global Title Translations

7.6 SCCP Configuration Reference

: 7.6.1 General Parameters
: 7.6.2 User Service Access Point (USAP) Definitions
: 7.6.3 Network Service Access Point (NSAP) Definitions
: 7.6.4 Address Translation Definitions
: 7.6.5 Route Definitions

7.1 Introduction to the SCCP Layer

The SS7 SCCP layer builds on the services of the MTP layer to provide SS7 applications with a higher level transport subsystem. In particular the SCCP layer adds the following services to those provided by the MTP layers. The ability to address individual applications or databases, known as subsystems, at a signaling point through a SCCP-level address consisting of a point code and a subsystem number; An OSI-like connectionless transport service; An OSI-like connection-oriented transport service; An address translation mechanism, called global title translation, which can translate a string of digits (such as a telephone number or mobile identification number) into a point code and/or subsystem number, isolating applications from changes in the physical SS7 network structure. A subsystem management layer which tracks the status of targeted subsystems at particular signaling points, known as concerned signaling points, and can optionally associate a backup signaling point with a subsystem for high availability applications.
Applications access these services either directly from the SCCP layer or indirectly through the TCAP layer.
The SS7 SCCP layer implements these services through the configuration of several entities: User Service Access Points, Network Service Access Points, Routes, and Address Translations, in addition to general configuration parameters which control the operation of the SCCP layer as a whole.
User Service Access Points (User SAPs) define the interface between the user applications and the SCCP layer. One user SAP is defined for each application using the SCCP layer services. A user SAP is associated with a single subsystem number and protocol variant (ANSI or ITU-T). The user SAP defines whether the application is replicated on another node for reliability purposes, and lists any concerned point codes (i.e., nodes which must be notified of any change in the status of the application). Figure 7 illustrates the concept of user SAPs. Note that when the application interfaces to the TCAP layer, the TCAP SAPs map one-for-one with a SCCP user SAP. Figure 7. SCCP User Service Access Points
Network SAPs define the interface between the SCCP layer and the MTP layer 3. One network SAP is defined for each MTP 3 layer interface that the SCCP layer uses. Typically the SCCP layer has only a single network SAP, although if the same system supports multiple protocol variants (ANSI and ITU-T), the SCCP layer would have a separate network SAP for each switch type.
One route is defined for each destination signaling point that the SCCP layer may be used to access. The route defines the destination point code of that signaling point and each subsystem of interest at that signaling point as well as any backup point codes which replicate those subsystems. If the SCCP default routing feature is employed, all routing is deferred to the MTP layers and no SCCP routes need not be defined. This is described in detail in Section 7.4.
Address Translation entries define how the SCCP layer is to translate and/or route between global titles, point codes, and subsystem numbers. Global title translation is described in more detail in Section 7.5.
Figure 8 illustrates the relationship between the various configurable entities. Figure 8. SCCP Configurable Entities

7.2 The SCCP Configuration

The SS7 SCCP software contains a utility program sccpcfg which reads a text configuration file and downloads the specified configuration to the SCCP task on the TX board, typically as part of the download sequence.
The general format of the SCCP configuration file is provided here: <General Configuration Parameters> <User SAP 0 definition> <SAP Parameters> END <User SAP n-1 definition> <SAP Parameters> END <NSAP definition> <NSAP Parameters> END <Address Translation definition> <Address Translation Parameters> END <Address Translation definition> <Address Translation Parameters> END <Route 0 definition> <Route Parameters> END <Route m-1 definition> <Route Parameters> END

7.3 Sample SCCP Configuration File

The SCCP distribution software contains sample configuration files for both ANSI and ITU-T configurations. These configurations may be used in conjunction with the MTP sample configuration files to test SCCP applications using two TX boards in a back-to-back arrangement (see Chapter 3). The following example shows the sample ANSI configuration file for one board. Note: All SCCP timer values are in seconds; a timer value of zero disables that timer. # # Sample SCCP configuration file for the following configuration # # General: # 4 user APPs max # 1 MTP3 network SAP # all others general defaults # User SAPs: # ANSI-92, 1.1.2 is concerned PC # Network Saps: # ANSI, point code = 1.1.1 # Routes: # 1 to 1.1.2, SSNs 3 & 4, 1.1.2 is concerned PC # Address translations: # 8477069701 = far point code, SSN 3, 8477069700 # 847xxxxxxx = far point code, SSN 4 # # General Configuration Section MAX_USERS 4 # Max SCCP user applications MAX_NSAPS 2 # Number of MTP3 interface (max 1 # per switch type) MAX_SCLI 1 # Max simultaneous sequenced # connectionless data xfers (Class 1 only) MAX_ADDRS 2 # Max Address translation entries MAX_ROUTES 10 # Max far point codes SCCP knows DEF_ROUNTING FALSE # Set Default Routing (FALSE=OFF, TRUE=ON) SAVE_CONNS FALSE # Drop connections on lost link # (FALSE) or don't drop (TRUE). ALARM_LEVEL 1 # Set alarm level reporting (0=off, # 1=default, 2=debug, 3=detail) TRACE_DATA FALSE # Set data tracing (FALSE=OFF, TRUE=ON) MAX_ADJDPC 2 # Max far point codes directly adjacent to us MAX_MSGDRN 5 # Max msgs to send in a batch when MTP comes # up. (prevents flooding when link(s)come up) MAX_XUDT 1 # Number of control blocks to allocate for # reassembling segmented extended # UnitDaTa (ITU-92 only) MAX_XUDTXREF 2 # Max number of local references # used to segment eXtended UnitDaTa MAX_CONN 512 # Max number of simultaneous connections CONN_THRESH 1 # Minimum number of SCCP buffers # that must be available for new # connection to be accepted QUEUE_THRESH 8 # Max number of buffers that can # be queued for connection waiting # for conn window to open SOG_THRESH 3 # Minimum number of SCCP buffers # that must be available for SOR # request from replicated (backup) # subsystem to be accepted # Note all timer values are in seconds (0 disables timer) XREFFRZ_TIMER 2 # wait before reusing local reference #ASMB_TIMER 0 # wait for all segments of # segmented XUDT (ITU-92 only) FREEZE_TIMER 2 # wait before reusing connection reference CONN_TIMER 180 # wait for response to connection request TXINACT_TIMER 600 # wait with no outgoing packets on # a connection before issuing # Inactivity test (IT) message RXINACT_TIMER 900 # wait with no incoming packets on # a connection before releasing # connection (should be > TXINACT_TIMER) REL_TIMER 10 # wait for response to release request #REPREL_TIMER 0 # wait for response to 2nd release # request (ITU only) #INTERVAL_TIMER 0 # wait before reporting abnormal # release (ITU only) GUARD_TIMER 2 # wait after MTP3 traffic restart # before application traffic RESET_TIMER 30 # wait for response to Reset Request #SCLI_TIMER 0 # max time sequenced # connectionless transmission can # take(class 1) SST_TIMER 30 # time between subsystem status tests SRT_TIMER 30 # time between subsystem routing tests NSAP_TIMER 1 # time between bursts of messages # to MTP3 when draining built-up # queue (prevents congestion when # link comes back up IGNORE_TIMER 30 # delay after receiving SOG before # actually going out of service COORD_TIMER 30 # wait for grant to go out of # service (SOG) after issuing SOR request END # # User SAP configuration for 1st application # USER_SAP 0 # Sap number start at 0 SWITCH_TYPE ANSI92 # one of ITU92, ITU88, ANSI92, ANSI88 #BACKUP_PC 1.2.3 # this application not replicated for now #Concerned point codes (Nodes to be notified of App's availability) up to 8 CONC_PC 1.1.2 ADDR_MASK FFF0000000 # requires match on only 1st 3 # digits of global title MAX_HOPS 10 # maximum network hops END # User application 0 # # User SAP configuration for 2nd application # USER_SAP 1 # Application 1 SWITCH_TYPE ANSI92 # one of ITU92, ITU88, ANSI92, ANSI88 #BACKUP_PC 1.2.3 # this application not replicated for now #Concerned point codes (Nodes to be notified of App's availability) up to 8 CONC_PC 1.1.2 ADDR_MASK FFF0000000 # requires match on only 1st 3 # digits of global title MAX_HOPS 10 # maximum network hops END # User application 1 # # User SAP configuration for 3rd application # USER_SAP 2 # Application 2 SWITCH_TYPE ANSI92 # one of ITU92, ITU88, ANSI92, ANSI88 #BACKUP_PC 1.2.3 # this application not replicated for now # Concerned point codes (Nodes to be notified of Apps availability) up to 8 CONC_PC 1.1.2 ADDR_MASK FFF0000000 # requires match on only 1st 3 # digits of global title MAX_HOPS 10 # maximum network hops END # User application 1 # # User SAP configuration for 4th application # USER_SAP 3 # Application 3 SWITCH_TYPE ANSI92 # one of ITU92, ITU88, ANSI92, ANSI88 #BACKUP_PC 1.2.3 # this application not replicated for now # Concerned point codes (Nodes to be notified of App's availability) up to 8 CONC_PC 1.1.2 ADDR_MASK FFF0000000 # requires match on only 1st 3 # digits of global title MAX_HOPS 0 # maximum network hops END # User application 1 # # Network (MTP3) Saps - one per switch type # NSAP 1 # SCCP must be NSAP 1 if isup present too SWITCH_TYPE ANSI # one of ITU, ANSI DPC 1.1.1 # REQUIRED - this node's point code DPC_LEN 4 # normally wouldn't specify this - # let it default based on switch type MSG_LEN 256 # MTU length on this network TXQ_THRESH 20 # max packets queued to this MTP3 ADDR_MASK FFFFFFFFFF # match 10 digits for global title # translation of incoming packets MAX_HOPS 10 # maximum network hops END # of ANSI MTP3 NSAP # # Address Translations: 8477069701 # ADDRESS 8477069701 # global title - incoming REPLACE_GLT TRUE # remove translated global title # from message SWITCH_TYPE ANSI # one of ITU, ANSI NI_IND NATIONAL # one of NATIONAL [NAT],INTERNATIONAL [INTL] ROUTING_IND C_SSN # set outgoing routing flag(PC_SSN or GLT) DPC 1.1.2 # translated destination point code SSN 3 # translated subsystem number GT_FORMAT 1 # outgoing global title includes # translation type, numbering # plan, and encoding scheme TRANS_TYPE 2 # translation type NUM_PLAN 1 # ISDN numbering plan GL_TITLE 8477069700 # outgoing global title END # of address translation for 8477069701 # # Address Translations: 847xxxxxxx # ADDRESS 847 # global title - incoming REPLACE_GLT FALSE # include translated global title # in message SWITCH_TYPE ANSI # one of ITU, ANSI NI_IND NATIONAL # one of NATIONAL [NAT].INTERNATIONAL [INTL] ROUTING_IND GLT # set outgoing routing flag(PC_SSN or GLT) DPC 1.1.2 # translated destination point code SSN 4 # translated subsystem number END # of address translation for 847xxxxxxx # # Routes: 1 for each node known to the SCCP layer # ROUTE 1.1.2 # destination point code SWITCH_TYPE ANSI # one of ITU, ANSI ADJACENT TRUE # this dest directly adjacent TRANSLATOR FALSE # not a translator node #BACKUP_PC x.y.z # this node not currently replicated #define all subsystems of interest at 1.1.1 (up to 8) SSN 3 # first subsystem at 1.1.2 SSN_SNR TRUE # normal routed SSN_ACC TRUE # initially accessable #SSN_BPC x.y.z # this subsystem not currently replicated # concerned point codes - other nodes to be notified when # status of this SSN at this node changes - must have a # route for any point code listed here #CONC_PC q.r.s # 1st concerned point code #CONC_PC q.r.t # 2nd concerned point code END # of route 1.1.2, SSN 3 SSN 4 # another subsystem at 1.1.2 SSN_SNR TRUE # normal routed SSN_ACC TRUE # initially accessable #SSN_BPC x.y.z # this subsystem not currently replicated #concerned point codes - other nodes to be notified when # status of this SSN at this node changes - must have a # route for any point code listed here #CONC_PC q.r.s # 1st concerned point code #CONC_PC q.r.t # 2nd concerned point code END # of route 1.1.2, SSN 4 END # of route 1.1.2

7.4 Using Default Routing

The SCCP Default Routing feature allows routing of SCCP packets generated by local applications (either directly via the SCCP API or through the SS7 TCAP layer) to signaling points whose point codes and subsystem numbers are not pre-configured.
This feature is primarily intended for applications that will act as databases, or servers, in an SS7 network and cannot be pre-configured with the point codes of all clients that will access the server. This feature may also be suitable for other SCCP and/or TCAP based applications that do not require the signaling point and subsystem management features of the SCCP management functions, such as replicated subsystems.

7.4.1 Introduction

When default routing is enabled, the SCCP layer attempts to deliver messages for which it has no explicit route entry by relying solely on the MTP layer routing. This applies to all classes of SCCP messages: connectionless, connection-oriented, and management. This effectively disables all SCCP management functionality for those remote signaling points/subsystems without explicit routes. This has several ramifications, which are described in Section 7.4.5, SCCP Limitations When Default Routing is Enabled.
When default routing is enabled, it may still be desirable to pre-configure routes to certain known destinations, such as adjacent STPs/translators, or other remote subsystems which are replicated and require the SCCP management procedures for routing to backup signaling points in case of outages or congestion.

7.4.2 Enabling Default Routing

Default routing is disabled by default. To enable default routing, the following statement is added to the general configuration parameters section of the SCCP configuration file. DEF_ROUTING TRUE # Default Routing (FALSE = OFF, TRUE = ON)

7.4.3 Impact of Default Routing on SCCP Message Routing

Routing of outbound messages by the SCCP layer is now performed as follows. Global title translation, if necessary, is performed on the outbound message. The SCCP layer checks for an explicit route to the destination point code. If an explicit route exists, the status of the destination signaling point and subsystem, if known, are checked. If the destination signaling point is active and the destination subsystem available (or unknown - i.e., routing by global title), the message is passed to the MTP 3 layer for delivery. If the signaling point is not accessible or the subsystem is unavailable, standard routing failure treatment is applied. If no explicit route exists for the destination point code and default routing is disabled, standard routing failure treatment is applied. If no explicit route exists for the destination point code and default routing is enabled, the message is passed to MTP 3 for delivery. If the MTP 3 layer is unable to deliver the message for any reason, the message is discarded and no notification is given to the application that originated the message.

7.4.4 Impact of Default Routing on SCCP Management

The SCCP layer does not attempt to track the status of signaling points and subsystems which are not explicitly defined with route entries. Subsystem prohibited (SSP) and subsystem allowed (SSA) messages received for signaling points with no explicit route entry are ignored. Likewise, pause, resume, and remote user unavailable indications from the MTP 3 layer regarding signaling points with no explicit route entry are ignored. In effect, signaling points/subsystems with no explicit route entry are always considered available at the SCCP layer.
Subsystem testing is applied only to explicitly configured signaling points and subsystems (i.e., SST messages are never sent to destinations with no explicit route entry defined).
If a subsystem test (SST) message is received from a signaling point which is not explicitly configured with a route entry, the appropriate response (SSA if the local subsystem is available, no response if the local subsystem is prohibited or unequipped) is returned, provided that the MTP 3 layer is able to route the response to that signaling point.
If the SCCP layer receives a message from an unknown (i.e., not explicitly configured) remote signaling point for a local subsystem which is either prohibited or unequipped, a subsystem prohibited (SSP) message is returned to the originating signaling point, provided that the MTP 3 layer is able to route to that signaling point. The appropriate message return (connectionless) or connection refusal (connection request) procedures are also performed.

7.4.5 SCCP Limitations When Default Routing is Enabled

As described above, use of default routing effectively disables the SCCP layer management functions for those signaling points not explicitly configured with route entries. This section summarizes many of the limitations which result from the use of default routing.

If a local subsystem is to be replicated and take advantage of the SCCP layer's ability to route incoming messages to the backup signaling point when the local application is unavailable, an explicit route to the backup signaling point must be configured.

If a remote subsystem is to be replicated and take advantage of the SCCP layer's ability to route outgoing messages to the backup signaling point when the primary signaling point or subsystem is unavailable, explicit routes to both the primary and backup signaling points must be configured.

If a local application (SCCP or TCAP API user) wishes to receive status indications for a remote signaling point/subsystem when it becomes available, unavailable, or congested then an explicit route entry must be configured for each such remote signaling point and it must be listed as a concerned point code in the application's user SAP configuration.

If a remote subsystem is to receive automatic SSP and SSA messages when a local application (SCCP or TCAP API user) declares itself unavailable/available then an explicit route entry must be configured for each such remote signaling point and it must be listed as a concerned point code in the application's user SAP configuration.

Subsystem prohibited (SSP) and subsystem allowed (SSA) messages received for signaling points with no explicit route entry are ignored. In effect, signaling points/subsystems with no explicit route entry are always considered available at the SCCP layer.

7.5 Configuring Global Title Translations

The SS7 SCCP layer supports global title translation, a feature which allows applications to address messages via a string of digits, such as a telephone number or a mobile identification number, and rely on the network configuration to route the message to the correct destination signaling point and subsystem. This can help isolate applications from changes in the network structure, such as when a particular network database is moved from one signaling point code to another. This feature is available for both applications accessing the SCCP layer directly and for applications using the SCCP layer indirectly through the TCAP layer.
The SCCP layer can translate a global title into its final destination address (point code and subsystem number) or, more likely, into the address of a gateway STP. A gateway STP is typically an STP containing a global title translation capability which acts as the entry point to a network for all requests originating from outside the network. In either case, the global title digits may be carried through in the translated address for subsequent translation by the gateway STP or analysis by the destination application.
Consider the example network diagram shown in Figure 9. The SCCP application uses both the "800 number translation" and "900 number translation" services provided by the databases shown. Figure 9. Example Global Title Translation Network Diagram
In this case, the network addresses (point codes) of these databases are not known to the node; only the address of the gateway is configured in the SS7 configuration files.
When the application sends a request for either an "800 number" or "900 number" translation, it generates a SCCP request (or TCAP request) with the 10-digit 800 or 900 number to be translated as the global title digits and the routing indicator field set to "route by global title". The application does not include a point code or subsystem number in the destination address.
The following SCCP sample configuration illustrates the configuration of the address translation. The ADDRESS_MASK parameter for the user SAP that corresponds to this application is set to FFF0000000. This causes the SCCP layer to choose the first address translation entry whose first 3 digits match the first 3 global title digits in the message whose address is being translated. The configured address translation for both 800 and 900 numbers specifies the point code of the gateway STP, which will perform subsequent global title translation on the message's destination address to insert the actual point code of the appropriate database. A subsystem number is also included here, although it could also be inserted by the gateway STP. The configured address translation for both 800 and 900 numbers specifies a routing indicator of "route by global title" to indicate to the gateway STP to perform global title translation; it also indicates that the original global digits are not to be replaced in the outgoing message so that the gateway STP may perform the subsequent translation. The following example illustrates ANSI address formats: # # Sample configuration of Global Title Translation < General Parameters > # User SAP configuration for example application USER_SAP 0 # Application 1 SWITCH_TYPE ANSI92 # protocol variant CONC_PC 2.199.0 # Gateway STP ADDR_MASK FFF0000000 # match 1st 3 global title digits END # User application 0 # Address Translations: 800XXXXXXX numbers ADDRESS 800 # global title - incoming REPLACE_GLT FALSE # retain global title in message SWITCH_TYPE ANSI # Address format - one of ITU, ANSI NI_IND NATIONAL # national address format DPC 2.199.0 # translated destination point code SSN 254 # translated subsystem number ROUTING_IND GLT # set outgoing routing flag to GLT END # of address translation for 800xxxxxxx # Address Translations: 900XXXXXXX numbers ADDRESS 900 # global title - incoming REPLACE_GLT FALSE # retain global title in message SWITCH_TYPE ANSI # Address format - one of ITU, ANSI NI_IND NATIONAL # national address format DPC 2.199.0 # translated destination point code SSN 254 # translated subsystem number ROUTING_IND GLT # set outgoing routing flag to GLT END # of address translation for 900xxxxxxx < Route entry for gateway STP >

7.6 SCCP Configuration Reference

There are five major sections of the SCCP configuration file - general parameters, user SAP definition, network SAP definition, routes, and circuits.

7.6.1 General Parameters

The general parameters configuration section defines the operational characteristics of the SCCP layer, such as upper bounds for internal data structures (these determine the amount of memory used by the SCCP layer), queue thresholds, and various protocol timer values. It is the first section of the configuration file.

Field Name

Default

Range

Description

MAX_USERS

2

1-255

Maximum number of user SAPs

MAX_NSAPS

1

1-255

Maximum number of network SAPs

MAX_SCLI

20

0-65535

Maximum number of simultaneous sequenced connectionless data transfers.

MAX_ADDRS

7

0-65535

Maximum number of address translation entries

MAX_ROUTES

4

0-65535

Max. number of route entries

MAX_ADJDPC

4

0-65535

Maximum number of point codes that can be specified as "adjacent"; i.e., are notified directly by this node of status changes.

MAX_MSGDRN

5

0-65535

Maximum number msgs queued to MTP3 to send in one "time interval" when exiting flow control (5 is the suggested default).

MAX_XUDT

0

0-65535

Maximum number of control blocks to allocate for reassembling segmented extended unit data (used only for ITU-92, should be zero for ANSI operation).

MAX_XUDTXREF

0

0-65535

Maximum number of local references used to segment extended unit data (used only for ITU-92, should be zero for ANSI operation).

MAX_CONN

512

0-65535

Maximum number of simultaneous connections

DEF_ROUTING

FALSE

TRUE | FALSE

Disable (FALSE) or enable (TRUE) default routing feature (see Section 7.4)

PC_FORMAT

DEFAULT

DEFAULT [DFLT],
INTER-NATIONAL [INTL],
JNTT

Point Codes are interpreted/displayed as 24-bit "8.8.8" values.
Point Codes are interpreted/displayed as 14-bit "3.8.3" values.
Point codes are interpreted/displayed as 16-bit "<M-Code>.<S-Code>.<U-Code>" values with the U-code in the most significant 7 bits, the S-code in the next 4 bits, and the M-code in the least significant 5 bits.

SAVE_CONNS

FALSE

TRUE | FALSE

Drop (FALSE) or retain (TRUE) connections when destination inaccessible.

ALARM_LEVEL

1

0-3

Alarm level reporting: 0=disable, 1=default, 2=debug, 3=detail

TRACE_DATA

FALSE

TRUE | FALSE

Disable (FALSE) or enable (TRUE) data tracing

CONN_THRESH

3

0-9

Minimum percentage of board memory that must be available before accepting a new connection in either direction; expressed in units of 10% (i.e., 3=30%)

QUEUE_THRESH

3

0-32766

Maximum number of data messages that may be queued for a connection waiting for the connection window to open.

SOG_THRESH

1

0-9

Minimum percentage of board memory that must be available before granting a Subsystem Out-of-Service (SOR) request from a backup signaling point, expressed in units of 10% (i.e. 3=30%)

SCLI_TIMER

2 Secs

0-65535

Maximum time that a sequenced connectionless transmission may take before control block is deallocated.

SST_TIMER

30 Secs

0-65535

Wait between subsystem status tests

NSAP_TIMER

1 Sec

0-65535

Time to wait between "draining" blocks of queued messages to the MTP 3 layer after exiting flow control (thus used to prevent flooding MTP 3 after network congestion abates - see also MAX_MSGDRN.

SRT_TIMER

30 Secs

0-65535

Wait between subsystem routing tests (ANSI only).

IGNORE_TIMER

30 Secs

0-65535

Time period after local subsystem goes out of service to ignore subsystem test messages.

COORD_TIMER

30 Secs

0-65535

Time to wait for response to coordinated state change request.

XREFFRZ_TIMER

1 Sec

0-65535

Time to freeze a XUDT local reference before reusing it (ITU-92 only).

ASMB_TIMER

20 Secs

0-65535

Maximum time for reassembling all segments of a XUDT message (ITU-92 only).

FREEZE_TIMER

1 Sec

0-65535

Time to freeze a connection local reference before reusing it.

CONN_TIMER

180 Secs

0-65535

Wait for response to connection request.

TXINACT_TIMER

600 Secs

0-65535

Wait with no outgoing packets on a connection before sending an Inactivity Test message.

RXINACT_TIMER

900 Secs

0-65535

Wait with no incoming packets on a connection before clearing connection (should be > TXINACT_TIMER)

REL_TIMER

4 Secs

0-65535

Wait for response to release request

REPREL_TIMER

4 Secs

0-65535

Time to wait for response to 2nd release request (ITU-T 92 only).

INTERVAL_TIMER

8 Secs

0-65535

Wait to report abnormal release timer.

GUARD_TIMER

1 Sec

0-65535

Time to wait after MTP 3 restart before allowing application traffic.

RESET_TIMER

6 Secs

0-65535

Time to wait for response to reset request.

END

REQUIRED - denotes end of section.

Field Name	Default	Range	Description
`MAX_USERS`	2	1-255	Maximum number of user SAPs
`MAX_NSAPS`	1	1-255	Maximum number of network SAPs
`MAX_SCLI`	20	0-65535	Maximum number of simultaneous sequenced connectionless data transfers.
`MAX_ADDRS`	7	0-65535	Maximum number of address translation entries
`MAX_ROUTES`	4	0-65535	Max. number of route entries
`MAX_ADJDPC`	4	0-65535	Maximum number of point codes that can be specified as "adjacent"; i.e., are notified directly by this node of status changes.
`MAX_MSGDRN`	5	0-65535	Maximum number msgs queued to MTP3 to send in one "time interval" when exiting flow control (5 is the suggested default).
`MAX_XUDT`	0	0-65535	Maximum number of control blocks to allocate for reassembling segmented extended unit data (used only for ITU-92, should be zero for ANSI operation).
`MAX_XUDTXREF`	0	0-65535	Maximum number of local references used to segment extended unit data (used only for ITU-92, should be zero for ANSI operation).
`MAX_CONN`	512	0-65535	Maximum number of simultaneous connections
`DEF_ROUTING`	`FALSE`	`TRUE \| FALSE`	Disable (`FALSE`) or enable (`TRUE`) default routing feature (see Section 7.4)
`PC_FORMAT`	`DEFAULT`	`DEFAULT [DFLT],` `INTER-NATIONAL [INTL],` `JNTT`	Point Codes are interpreted/displayed as 24-bit "8.8.8" values. Point Codes are interpreted/displayed as 14-bit "3.8.3" values. Point codes are interpreted/displayed as 16-bit "<M-Code>.<S-Code>.<U-Code>" values with the U-code in the most significant 7 bits, the S-code in the next 4 bits, and the M-code in the least significant 5 bits.
`SAVE_CONNS`	`FALSE`	`TRUE \| FALSE`	Drop (`FALSE`) or retain (`TRUE`) connections when destination inaccessible.
`ALARM_LEVEL`	1	0-3	Alarm level reporting: 0=disable, 1=default, 2=debug, 3=detail
`TRACE_DATA`	`FALSE`	`TRUE \| FALSE`	Disable (`FALSE`) or enable (`TRUE`) data tracing
`CONN_THRESH`	3	0-9	Minimum percentage of board memory that must be available before accepting a new connection in either direction; expressed in units of 10% (i.e., 3=30%)
`QUEUE_THRESH`	3	0-32766	Maximum number of data messages that may be queued for a connection waiting for the connection window to open.
`SOG_THRESH`	1	0-9	Minimum percentage of board memory that must be available before granting a Subsystem Out-of-Service (SOR) request from a backup signaling point, expressed in units of 10% (i.e. 3=30%)
`SCLI_TIMER`	2 Secs	0-65535	Maximum time that a sequenced connectionless transmission may take before control block is deallocated.
`SST_TIMER`	30 Secs	0-65535	Wait between subsystem status tests
`NSAP_TIMER`	1 Sec	0-65535	Time to wait between "draining" blocks of queued messages to the MTP 3 layer after exiting flow control (thus used to prevent flooding MTP 3 after network congestion abates - see also `MAX_MSGDRN`.
`SRT_TIMER`	30 Secs	0-65535	Wait between subsystem routing tests (ANSI only).
`IGNORE_TIMER`	30 Secs	0-65535	Time period after local subsystem goes out of service to ignore subsystem test messages.
`COORD_TIMER`	30 Secs	0-65535	Time to wait for response to coordinated state change request.
`XREFFRZ_TIMER`	1 Sec	0-65535	Time to freeze a XUDT local reference before reusing it (ITU-92 only).
`ASMB_TIMER`	20 Secs	0-65535	Maximum time for reassembling all segments of a XUDT message (ITU-92 only).
`FREEZE_TIMER`	1 Sec	0-65535	Time to freeze a connection local reference before reusing it.
`CONN_TIMER`	180 Secs	0-65535	Wait for response to connection request.
`TXINACT_TIMER`	600 Secs	0-65535	Wait with no outgoing packets on a connection before sending an Inactivity Test message.
`RXINACT_TIMER`	900 Secs	0-65535	Wait with no incoming packets on a connection before clearing connection (should be > `TXINACT_TIMER`)
`REL_TIMER`	4 Secs	0-65535	Wait for response to release request
`REPREL_TIMER`	4 Secs	0-65535	Time to wait for response to 2nd release request (ITU-T 92 only).
`INTERVAL_TIMER`	8 Secs	0-65535	Wait to report abnormal release timer.
`GUARD_TIMER`	1 Sec	0-65535	Time to wait after MTP 3 restart before allowing application traffic.
`RESET_TIMER`	6 Secs	0-65535	Time to wait for response to reset request.
`END`			REQUIRED - denotes end of section.

7.6.2 User Service Access Point (USAP) Definitions

One user SAP is defined for each application using the SCCP layer services. A user SAP is associated with a single subsystem number and switch type (ANSI88, ANSI92, ITU88, or ITU92). The user SAP defines whether the application is replicated on another node for reliability purposes, and lists any concerned point codes (i.e., nodes which must be notified of any change in the availability of the application). Field Name Default Range Description USER_SAP None 0-(MAX_USERS-1) Marks start of a User SAP definition; User SAP numbers start at 0 and are numbered sequentially up to MAX_USERS-1 SWITCH_TYPE ANSI92 ITU88, ITU92, ANSI88, ANSI 92 Protocol variant employed on this user SAP BACKUP_PC None Use "dotted" notation, e.g., 2.45.76 or hex number, e.g., 0x101. Point code where this subsystem is backed up. CONC_PC None Use "dotted" notation, e.g., 2.45.76 or hex number, e.g., 0x101. Concerned point code to be notified of changes in the availability of this application; up to eight CONC_PC entries (on separate lines) are allowed per User SAP. ADDR_MASK FFF...F N/A ASCII string describing which digits of global title to match on when performing global title translation (see note 1). MAX_HOPS 10 1-15 Hop count value to be used on outgoing SCCP messages from this SAP. END REQUIRED - denotes end of section. Note: Address masks are ASCII strings containing a 0 (zero) or f in each character position to determine whether the corresponding global title digit is used in the match. For example, the string 000fffffff will result in ignoring the 1st three digits and comparing only last 7 digits when searching the global title table for a match. Similarly, the string fff will compare only the first 3 digits to determine a match.

7.6.3 Network Service Access Point (NSAP) Definitions

The Network SAP defines the point at which the SCCP layer accesses the network (MTP 3) layer. One network SAP is defined for each switch type (ANSI or ITU-T) supported. The NSAP number assigned in this section (NSAP <number> statement) must match a valid NSAP number defined in the NSAPs section (NSAP <number> statement) of the MTP 3 configuration file. Note: If both the SCCP and ISUP layers are used on the same board, the SCCP layer cannot be assigned to MTP3 NSAP 0 (zero); ISUP always uses this NSAP. Field Name Default Range Description NSAP None 0-(MAX_NSAPS-1) Marks start of a Network SAP definition; NSAP numbers start at 0 and are numbered sequentially up to MAX_NSAPS-1 (this must match a NSAP number defined in the MTP 3 configuration). SWITCH_TYPE ANSI ITU, ANSI Protocol variant employed on this NSAP SSF NATL (ANSI), INTL (ITU) INTERNATIONAL | ITL, SPARE, NATIONAL | NATL, RESERVED | RES The value to be used in the sub-service field for this network; DPC None Use "dotted" notation, e.g., 2.45.76 or hex number, e.g., 0x101 REQUIRED - Point code of this node on this network interface. DPC_LEN 24 (ANSI | ITU) 14 (ITU) 14 | 24 Point code length employed on this network MSG_LEN 256 32-1500 Maximum length of a message passed to MTP 3 on this SAP. TXQ_THRESH 20 0-32766 Maximum number of messages to queue to MTP 3 (i.e., when flow control is on) before discarding. ADDR_MASK FFF...F N/A Ascii string describing which digits of global title to match on when performing global title translation (See note below and also note from User SAP section). MAX_HOPS 10 1-15 Hop count value to be used when returning undeliverable incoming messages back to the source of the message. END REQUIRED - denotes end of section. Note: The Network SAP address mask is used only when providing global translation for incoming messages (those received from the network). For messages originated by an application on this node, the User SAP address mask is used.

7.6.4 Address Translation Definitions

Address entries define how the SCCP layer is to translate and/or route between global titles, point codes, and subsystem numbers. A global title may translate into one of the following.
A point code and subsystem number (use GT_FORMAT 0)
Another global title only (in this case the message to be routed must include a destination point code in addition to the incoming global title)
Another global title + point code
Another global title + subsystem number (in this case the message to be routed must include a destination point code in addition to the incoming global title)
Another global title + point code + subsystem number

Multiple address translations may be configured, up to the MAX_ADDRS value specified in the general parameters section. Field Name Default Range Description ADDRESS None N/A Incoming global title string, ascii (ASCII digits; i.e. "0"-"9" REPLACE_GLT FALSE TRUE | FALSE If TRUE, replace translated global title in outgoing message If FALSE, incoming global title and translated point code & subsystem are copied to outgoing message. SWITCH_TYPE ANSI ITU | ANSI Format of this address NI_IND NAT NATIONAL | NAT, INTERNATIONAL | INTL National/International indicator ROUTING_IND PC_SSN PC_SSN, GLT Routing indicator for translated address, either "route by PC & SSN" or "route by global title" SSN None 0-255 Translated subsystem number (required for GT_FORMAT 0) DPC None Use "dotted" notation, e.g., 2.45.76 or hex number, e.g., 0x101 Translated destination point code (required for GT_FORMAT 0) GT_FORMAT 0 0...4 Defines structure of outgoing global title. Used only when REPLACE_GLT parameter is TRUE. 0 No global title translation. 1 ANSI: Outgoing global title includes translation type, numbering plan, and encoding scheme. ITU: Outgoing global title includes nature of address indicator. 2 ANSI and ITU: Outgoing global title includes translation type only. 3 ITU only: Outgoing global title includes translation type, numbering plan, and encoding scheme. 4 ITU only: Outgoing global title includes translation type, numbering plan, encoding scheme, and nature of address indicator. GL_TITLE None N/A Outgoing global title string (ASCII digits; i.e. "0"-"9"). Used only when REPLACE_GLT parameter is TRUE TRANS_TYPE 0 0-255 Outgoing global title translation type, used only when REPLACE_GLT parameter is TRUE NAT_ADDR 3 0-4 Outgoing global title nature of address indicator (ITU only). Used only when REPLACE_GLT parameter is TRUE NUM_PLAN 1 0-15 Outgoing global title numbering plan (ISDN Numbering Plan). Used only when REPLACE_GLT parameter is TRUE END REQUIRED - denotes end of section.

7.6.5 Route Definitions

A route configuration entry defines a point code (and its subsystems) known to this node. A route entry must be defined for each point code and switch type to which this node may send SCCP messages.
Note: Each route definition contains one or more subsystem definitions, each of which spans multiple lines and is terminated with an END statement. Each route definition as a whole is also terminated with an END statement. Mismatched END statements are a common cause of configuration errors and can cause unpredictable results.

Field Name

Default

Range

Description

ROUTE

None

Use "dotted" notation, e.g., 2.45.76 or hex number, e.g., 0x101

REQUIRED - Destination point code

SWITCH_TYPE

ANSI

ITU | ANSI

Protocol variant for this point code

TRANSLATOR

TRUE

TRUE | FALSE,

If TRUE, this signaling point is a translator node

ADJACENT

TRUE

TRUE | FALSE,

If TRUE, this signaling point is adjacent for SCCP point code & subsystem management procedures

BACKUP_PC

None

Use "dotted" notation, e.g., 2.45.76 or hex number, e.g., 0x101

Backup point code. If not present, signaling point is not replicated

SSN

None

0-255

Subsystem number, also denotes beginning of Subsystem definition subsection which itself is terminated by END statement; up to 8 subsystem definition subsections may be included in each route definition.

SSN_SNR

TRUE

TRUE | FALSE,

Subsystem is normal routed (TRUE) or backup routed (FALSE)

SSN_ACC

TRUE

TRUE | FALSE,

Subsystem is initially accessible (TRUE) or not (FALSE)

SSN_BPC

None

Use "dotted" notation, e.g., 2.45.76 or hex number, e.g., 0x101

Subsystem backup point code (if not present, subsystem is not replicated)

CONC_PC

None

Use "dotted" notation, e.g., 2.45.76 or hex number, e.g., 0x101

Concerned point code to be notified of changes in the availability of this subsystem; up to eight CONC_PC entries (on separate lines) are allowed per subsystem per route.

END

REQUIRED - denotes end of current subsystem definition subsection (repeated for each separate SSN section within this route entry).

END

REQUIRED - denotes end of current route definition section.

Field Name	Default	Range	Description
`ROUTE`	None	Use "dotted" notation, e.g., 2.45.76 or hex number, e.g., 0x101	REQUIRED - Destination point code
`SWITCH_TYPE`	`ANSI`	`ITU \| ANSI`	Protocol variant for this point code
`TRANSLATOR`	`TRUE`	`TRUE \| FALSE,`	If `TRUE`, this signaling point is a translator node
`ADJACENT`	`TRUE`	`TRUE \| FALSE,`	If `TRUE`, this signaling point is adjacent for SCCP point code & subsystem management procedures
`BACKUP_PC`	None	Use "dotted" notation, e.g., 2.45.76 or hex number, e.g., 0x101	Backup point code. If not present, signaling point is not replicated
`SSN`	None	0-255	Subsystem number, also denotes beginning of Subsystem definition subsection which itself is terminated by `END` statement; up to 8 subsystem definition subsections may be included in each route definition.
`SSN_SNR`	`TRUE`	`TRUE \| FALSE,`	Subsystem is normal routed (`TRUE`) or backup routed (`FALSE`)
`SSN_ACC`	`TRUE`	`TRUE \| FALSE,`	Subsystem is initially accessible (`TRUE`) or not (`FALSE`)
`SSN_BPC`	None	Use "dotted" notation, e.g., 2.45.76 or hex number, e.g., 0x101	Subsystem backup point code (if not present, subsystem is not replicated)
`CONC_PC`	None	Use "dotted" notation, e.g., 2.45.76 or hex number, e.g., 0x101	Concerned point code to be notified of changes in the availability of this subsystem; up to eight `CONC_PC` entries (on separate lines) are allowed per subsystem per route.
`END`			REQUIRED - denotes end of current subsystem definition subsection (repeated for each separate SSN section within this route entry).
`END`			REQUIRED - denotes end of current route definition section.

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