SSNC Introduction

Information

Signaling

Signaling System Network Control(SSNC)

A50016-D1109-K401-1-7618

2 A50016-D1109-K401-1-7618

Signaling System Network Control (SSNC) InformationSignaling

f Important Notice on Product SafetyElevated voltages are inevitably present at specific points in this electrical equipment. Some of theparts may also have elevated operating temperatures.

Non-observance of these conditions and the safety instructions can result in personal injury or in prop-erty damage.

Therefore, only trained and qualified personnel may install and maintain the system.

The system complies with the standard EN 60950 / IEC 60950. All equipment connected has to complywith the applicable safety standards.

The same text in German:

Wichtiger Hinweis zur Produktsicherheit

In elektrischen Anlagen stehen zwangsläufig bestimmte Teile der Geräte unter Spannung. Einige Teilekönnen auch eine hohe Betriebstemperatur aufweisen.

Eine Nichtbeachtung dieser Situation und der Warnungshinweise kann zu Körperverletzungen undSachschäden führen.

Deshalb wird vorausgesetzt, dass nur geschultes und qualifiziertes Personal die Anlagen installiert undwartet.

Das System entspricht den Anforderungen der EN 60950 / IEC 60950. Angeschlossene Gerätemüssen die zutreffenden Sicherheitsbestimmungen erfüllen.

Trademarks:

All designations used in this document can be trademarks, the use of which by third parties for theirown purposes could violate the rights of their owners.

Copyright (C) Siemens AG 2000.

Issued by Information and Communication MobileHofmannstraße 51D-81359 München

Technical modifications possible.Technical specifications and features are binding only insofar asthey are specifically and expressly agreed upon in a written contract.

A50016-D1109-K401-1-7618 3

InformationSignaling

Signaling System Network Control (SSNC)

This document consists of a total of 46 pages. All pages are issue 1.

Contents

1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

2 SSNC Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102.1 MTP Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102.1.1 Message transfer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102.1.2 Message safeguarding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112.1.3 Message handling and network management . . . . . . . . . . . . . . . . . . . . . . 132.2 SCCP Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152.3 Standalone STP functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

3 SSNC Hardware . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 163.1 Main processor (MP). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 163.2 ATM Switching network (ASN) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 183.3 Line interface card (LIC) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 203.4 ATM Bridge processor, type C (AMPC) . . . . . . . . . . . . . . . . . . . . . . . . . . . 213.5 ATM Interface module (ATM230) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 233.6 Standalone STP Architecture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

4 SSNC Software. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 244.1 Software architecture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 244.2 Software units . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 264.3 Load model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

5 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 305.1 SS7 Screening . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 305.2 SS7 Accounting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 305.3 High-Speed Signaling Links (HSL) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 315.4 Multiple SS7 Networks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 315.5 Global Title Translation (GTT) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 315.6 MTP Route Verification Test (MRVT) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 315.7 Extended load sharing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 325.8 SS7 Traffic structure measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 335.9 Additional features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

6 SSNC Performance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

7 SSNC Operation, administration and maintenance . . . . . . . . . . . . . . . . . . 367.1 Operations, maintenance and administration part (OMAP) . . . . . . . . . . . . 367.2 Administration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 397.3 Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

8 SSNC Database . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

4 A50016-D1109-K401-1-7618


A50016-D1109-K401-1-7618 5



1 IntroductionThe most modern and most efficient methods to control traffic to and from other networknodes is Signaling System No. 7 (SS7). It transfers messages separately from user in-formation (speech, data) along common channel signaling links.

The common signaling channels form a (logically) separate signaling network. They in-terconnect the signaling points.

Signaling points can be one or more of the following:– signaling end point (SEP)– signaling transfer point (STP)– signaling relay point (SRP)

The signaling points are integrated in the nodes of the communication network. Signal-ing transfer points can also be installed as independent nodes in the network (standal-one STP, SRP).

A network node functioning as a signaling end point represents a point of origin or pointof destination for signaling messages. A network node functioning as a signaling trans-fer point receives signaling messages from a signaling point and passes them to anothersignaling point. A network node functioning as a signaling relay point can perform globaltitle translation (GTT). A network node may function simultaneously as a signaling endpoint, signaling transfer point and signaling relay point.

The Signaling System Network Control (SSNC) is responsible for the control of SS7signaling traffic. The SSNC provides the protocol functions of the message transfer part(MTP) and the signaling connection control part (SCCP) and the operations, mainte-nance and administration part (OMAP).

The SSNC offers maximum efficiency for SS7 signaling. It can also be used as a gate-way between different networks, network operators or network topologies, such as ITU-T 14 bit, ITU-T 24 bit and ANSI 24 bit. For such applications SSNC offers special fea-tures for recording and verifying the amount of traffic with adjacent network nodes andalso for protecting the own network against misuse. It is also possible to administer upto 32 internal, independent networks. SSNC is a future-proof system which also sup-ports the connection of SS7 high-speed signaling links (HSL).

Position in the system

The SSNC belongs to the signaling area of the network node. Its position in the systemis shown in Fig. 1.1.

6 A50016-D1109-K401-1-7618


Fig. 1.1 Functional areas and subsystems

Features

The SSNC is characterized by the following features:– Asynchronous transfer mode (ATM) technology– Interworking between synchronous transfer mode (STM) and ATM– Maximum system configuration with 1500 signaling links and more than

100,000 message signal units per seconds (MSU/s)– Optional 1.5-Mbit/s or 2-Mbit/s ATM based high-speed signaling link interfaces

(see Fig. 1.2)– Reduction in CP loads by moving the OA&M functionality to the SSNC– Cost-effective standalone solution

For detailed performance values, see SSNC Performance.

Access Switching

Trunks, PBX, ISDN-PA,V5.2, SS7 (56/64 kbit/s), CAS

Signaling

high-speed SS7 links

Analog, ISDN-BA,V5.1, xDSL, IP

MB

CP

CCG

SwitchCommander

LTG

SSNC

SNDLU LTG

Management (OA&M) Control

A50016-D1109-K401-1-7618 7



Structure

The SSNC Functions are spread over several units. This results in a high degree of flex-ibility. Adaptation to future requirements regarding message throughput and new fea-tures is possible, due to the scalability of the main processor platform.

The SSNC Hardware comprises the following units (Fig. 1.2):• Line interface card (LIC)

The Line interface card (LIC) converts incoming message streams from the SS7 net-works from synchronous transfer mode with 1.5 Mbit/s or 2 Mbit/s to internal ATMcell streams with 207 Mbit/s and vice versa. The LIC is also the interface to high-speed links. Up to 248 signaling channels (8 E1/DS1) or 8 high-speed signalinglinks can be connected to a LIC.

• Main processor (MP)The Main processor (MP) is the key component of the SSNC.Up to 50 MP exist in the maximum SSNC configuration:– 1 MP up to a maximum of 47 MPs for signaling link termination (MP:SLT)– 1 MP for signaling manager (MP:SM)– 1 MP for statistics (MP:STATS)– 1 MP for operation, administration and maintenance (MP:OAM)The maximum system configuration allows the connection of 1500 signaling linksand a message throughput of more than 100 000 MSU/s.

• ATM Switching network (ASN)The ATM switching network (ASN) interconnects the individual MPs and links theLICs to the MP:SLTs.

• ATM Bridge processor, type C (AMPC)The ATM bridge processor, type C (AMPC) is the interface between the ATM equip-ment on the ASN and the coordination processor 113C (CP113C). It converts pack-et-oriented data flows from the ATM area to the CP communication mode and viceversa. For functional purposes the AMPC belongs to the SSNC, but it is located inthe module frame of the CP.

The mechanical design of the SSNC hardware is described in the Construction manual.

Interfaces

Fig. 1.2 illustrates the interfaces between the SSNC and– AMPC

2 x 207 Mbit/s per AMPC pair (optical fiber cable)(see description Coordination processor 113C/CR (CP113C/CR))

– Message buffer D (MBD)16 x 207 Mbit/s up to 32 x 207 Mbit/s(see description Message buffer D (MBD))

– LTG4 x 1.5 Mbit/s or 4 x 2 Mbit/s(see description Line/trunk group N (LTGN))

– NetManagerTCP/IP via Ethernet

8 A50016-D1109-K401-1-7618


Fig. 1.2 Hardware architecture of the SSNC with external/internal interfaces

In addition to the high-speed signaling links also 56/64 kbit/s signaling links can be di-rectly connected to the SSNC.

Internally the SSNC uses 207 Mbit/s ATM interfaces.

CP

SSNC

conventionalSS7 links(56/64 kbit/s)SS7-high-speedsignaling links(1,5 / 2 Mbit/s)

trunks andSS7 links(56/64 kbit/s)

1,5 / 2 Mbit/sSTM

207 Mbit/sATM

1,5 / 2 Mbit/sSTM/ATM

TCP / IP

LIC

LIC

MP:SLT

MP:SLT

MP:SM

MP:STATS

MP:OAMSwitch

Commander

LTG

MBD

LTG

AMPC

SN

ASN

207 Mbit/sATM

A50016-D1109-K401-1-7618 9



Standalone STP

The SSNC has a separate platform MP:OAM. As a consequence, the SSNC operation,administration and maintenance can be performed independently of the coordinationprocessor (CP). This means that the SSNC can be used as a cost-effective standaloneSTP without any other functional units (i.e. CP, SN, LTG) (Fig. 1.3).

A standalone STP can be used to implement the highest SS7 network level. It can alsobe used as SS7 gateway between different SS7 networks.

Fig. 1.3 Standalone STP

SSNC

TCP / IP

LIC

LIC

MP:SLT

MP:SLT

MP:SM

MP:STATS

MP:OAMSwitch

Commander

ASN

1,5 / 2 Mbit/sSTM/ATM

207 Mbit/sATM

SS7 links(56/64 kbit/s)SS7-high-speed signaling links(1,5 / 2 Mbit/s)

10 A50016-D1109-K401-1-7618


2 SSNC FunctionsThe functions of Signaling System No. 7 (SS7) are specially suited for the requirementsof digital networks. The separation of the functions into a common message transfer part(MTP) and several specific user parts (UP) results in a high degree of flexibility.

2.1 MTP FunctionsThe functions of the MTP are divided into three levels:• Level 1 – Message transfer (Q.702)• Level 2 – Message safeguarding (Q.703)• Level 3 – Message handling and network management (Q.704).

2.1.1 Message transferThe MTP level 1 function message transfer is the physical interface to the signaling sys-tem no. 7. It implements the transmission function of the signaling channels within thenetwork node. In the EWSD the line/trunk group (LTG) and the SSNC share this task.The message transfer is handled in the SSNC by the line interface card (LIC), the ATMswitching network (ASN) and the MP:SLT.

The following functions are performed in the receiving direction (see Fig. 2.1):– Reception of incoming SS7 messages as an STM byte stream in the LTG– Transfer of this byte stream from the LTG via the switching network (SN) to the LIC– In the LIC, packaging the bits that are contained in the time slot belonging to a sig-

naling channel into ATM cells (AAL1)– Transport of the ATM cells from the LIC through the ASN to the relevant MP:SLT re-

sponsible for the signaling link– Conversion of the ATM cells to MTP signaling units which are passed to message

safeguarding.

The procedure is reversed in the transmit direction.

High speed signaling links bypass LTG and SN and arrive directly at the LIC already inATM cell format.

A50016-D1109-K401-1-7618 11



Fig. 2.1 Functions of message transfer in the receiving direction (level 1)

2.1.2 Message safeguardingThe functionality of the MTP level 2 message safeguarding is divided into (see Fig. 2.2):– Management– Reception of signaling messages– Transmission of signaling messages

It is handled in the SSNC unit MP:SLT.

The management function consists of:– Link state control

This function supervises and controls the signaling link operating status and auto-matically takes faulty links into operation again.

– Processor outage controlA processor outage in the adjacent network node is detected, and the message traf-fic is diverted to other signaling channels accordingly

– Initial alignment controlThis function activates the signaling channels and starts their initialization test.

The reception function consists of:– Alignment error rate monitoring

This function checks the number of errors that occur during the initial synchroniza-tion in order to be able to align the links.

LIC

LTG

SLT

ASN

Reception ofSS7 messages

Transferto the SN and LIC

Packaging the bits intoATM cells

Conversion ofATM cells to MTP

signaling units

Transportto the SLT

Level 1functions

12 A50016-D1109-K401-1-7618


– Error rate monitoringThis function monitors the number of message errors occurring on a signaling linkduring a specified period. The level 3 manager is informed whenever a permittedthreshold value is exceeded.

– Congestion controlThis function monitors the reception, retransmission and transmission buffers bymeans of counters. Congestion in the receive buffer is reported to the remote send-er. Congestion in the sending direction is reported to the own level 3.

– Reception controlReceived messages and acknowledgements are monitored and verified.

The transmission function includes transmission control. It contains parts of the SS7protocol and is divided into:– Basic error correction method

A transmitted message is stored in the retransmission buffer until a positive acknowl-edgement is received. The message is retransmitted on request.

– Preventive cyclic retransmissionAt times when no new messages are being transmitted but unacknowledged mes-sages are still present in the retransmission buffer, these messages are retransmit-ted cyclically. Messages are also retransmitted if either a threshold for the numberof messages in the retransmission buffer or a threshold for the number of bytes tobe retransmitted is exceeded (forced retransmission).

Refer to the description Signaling System No. 7 (SS7) (Q.703) for information regardingthe general procedure for sending and receiving SS7 signaling messages.

High speed signaling links utilize the signaling ATM adaptation layer (SAAL) as level 2protocol.

A50016-D1109-K401-1-7618 13



Fig. 2.2 Functions of message safeguarding (level 2)

2.1.3 Message handling and network managementThese message transfer part (MTP) level 3 functions ensure the transfer of signalingmessages from a specific user part of an origination point to the same user part in thedestination point. These functions are handled in the SSNC by the function unitsMP:SLT and MP:SM (see Fig. 2.3).

The MP:SLT is responsible for the message handling . It includes the following func-tions:– Message routing

This function is used to determine an outgoing signaling link for a message signalunit (MSU). Using the route description, the current route (signaling link set), fromwhich the signaling link is taken, is selected. The message is then sent along thislink.

– Message discriminationThis function distinguishes the signaling messages received according to their des-tinations. If the messages are intended for the own network node, they are trans-ferred via the message distribution function to the appropriate user part. If themessages are destined to a different network node, they are transferred to the mes-sage routing function.

SLT

Link state control

Processor outage control

Initial alignment control

Alignment error ratemonitoring

Error rate monitoring

Congestion control

Reception control

Transmission control

Managementfunction

Receptionfunction

Transmissionfunction

Level 2functions

14 A50016-D1109-K401-1-7618


– Message distributionThis function identifies the user part for which the message is intended. The mes-sages are then transferred directly to the user parts or to the user allocation func-tions.

The MP:SM is responsible for the signaling network management . This is subdividedinto:– Signaling traffic management

This function is responsible for diverting the signaling traffic in the event of an error:to a different signaling link on the same route in the case of disturbances on a sig-naling link (changeover), or to an alternative route in the case of disturbances on aroute (rerouting).

– Signaling link managementThis function has to activate/deactivate the link sets and their links in response toinput commands or link errors.

– Signaling route managementThis function has to send status information regarding the signaling network and itsown MTP to adjacent MTPs in the event of errors occurring in the SS7 network or inits own MTP.

The testing & maintenance function (ITU-T Q.707) tests the path from the function’sown level 3 to the adjacent level 3. The test is performed when a link is activated perconfiguration request or restored after failure, after a remote processor outage situationhas ceased and periodical for active links on configuration demand.

A50016-D1109-K401-1-7618 15



Fig. 2.3 Message handling and network control functions (level 3)

2.2 SCCP FunctionsThe SCCP provides additional addressing and message transport functions for SS7. Fordetails on its realization in the SSNC see Signaling Connection Control Part (SCCP).

2.3 Standalone STP functionsThe task of a standalone STP is to forward incoming signaling messages. There are notrunk-related user part functions.

Because all required STP functions are already included and because of the SSNC’sown MP:OAM platform it is easy to deploy the SSNC as a stand-alone STP.

SLT

SM

Signaling traffic management

Signaling link management

Signaling route management

Message routing

Message discrimination

Message distribution

Test signaling links(for cutover)

Messagehandling

Signaling networkmanagement

Testing andmaintenance

Level 3functions

16 A50016-D1109-K401-1-7618


3 SSNC HardwareThe SSNC comprises the following hardware units:• Main processor (MP)• ATM Switching network (ASN)• Line interface card (LIC)• ATM Bridge processor, type C (AMPC)

The hardware units MP, LIC and AMPC are connected to the ASN via the ATM Interfacemodule (ATM230).

For a standalone STP configuration the AMPC is not required.

3.1 Main processor (MP)The SS7-specific functions are implemented on the different main processors (MP).Each MP comprises two Main processor units (MPU) and an Alarm indication module(ALI).

The two main processor units operate microsynchronously - i.e., each MPU processesthe same sequence of commands on the same clock cycle. To guarantee this, bothMPUs are initialized with identical states and all data are transmitted synchronously tothe two MPUs. The state of each MPU is checked at regular periods. The result is trans-mitted to the other MPU via the cross link (XLink) and compared with the test data gen-erated there.

If a hardware fault occurs in one of the two MPUs which leads to a loss of the microsyn-chronous parallel operation, both of them perform routine tests. The MPU that detectsthat it is faulty switches itself off. Once the faulty unit has been replaced, the new MPUmust be synchronized. Each MPU is responsible for detecting its own faults and report-ing them to the other MPU. This hardware self-fault detection function ensures that thefaulty MPU is taken out of operation.

The two MPUs are connected via the ATM interface (ATM230) with the ASN. BothMPUs receive ATM cells but only one of the two (the active MPU) transmits ATM cells.

Main processor units (MPU)

The MPU consists of the following major functional units located on one hardware mod-ule (see Fig. 3.1):– Intel P54CS (PP150-VRT) Pentium Processor (CPU).– ATM interface chip (ATM230)

The internal system communication and the loading of the system software are per-formed via this chip. The ATM230 has a line capacity of 207 Mbit/s to the ASN.

– Cross Link (XLink)This unit is a master/checker interface for communication and synchronization of thetwo MPUs. In addition, the synchronization between ATM230 and processor activi-ties is performed here along with checks on the clock generation.

– Boot flash EPROM (FEPROM)Each of the three FEPROMs has a capacity of 2 Mbytes. The FEPROMs contain theboot software and hardware test programs needed for startup of the MPU. TheFEPROMs are connected with the ATM230 bus.

– Small Computer System Interface (SCSI)Supports the connection of a magnetic disk device (MDD) and magneto-optical diskdevice (MOD). The MDD is a device used as an off-board mass storage for the stan-

A50016-D1109-K401-1-7618 17



dalone STP with a capacity of 9 GByte. The MOD is used to enable loading of soft-ware and configuration data into the MP:OAM. The maximum data transfer rate ona SCSI bus is asynchronously 7 Mbyte/s and synchronously 10 Mbyte/s.

– Power supply unit (PSU)Each MPU has its own power supply. Power failure in an MPU in a redundant systemdoes not cause an alarm if the other MPU is in order.

– Ethernet interfaceThis interface is used for connection to a LAN.

Alarm indication module (ALI)

The main processor (MP) is additionally equipped with an alarm indication module (ALI).Unlike the MPU, the ALI is not duplicated. The ALI indicates the alarm status of the sys-tem. It is connected via two serial ports with the two main processor units. Only the ac-tive MPU controls the ALI. Two power supply units, each with 12 V / 500 mA, providepower.

The ALI has the following main interfaces:– 16 inputs for external alarms– 4 inputs for internal alarms, for example, to monitor temperature– 3 LEDs for critical (red), major (red) and minor (yellow) alarms– 4 relays for critical, major, minor and PCM alarms– 2 LEDs (red, green) for the status of the ALI (controlled by a watchdog and MPU)– combined V.24 radio clock interface– monitoring of total MPU failure

Fig. 3.1 Structure of the MP hardware

LAN

RadioClock

AlarmInputs/Outputs

MOD

LAN

LAN

XLink

ALI

MDD

MOD MDD

ACCG1

ACCG0

AMXE1

AMXE1

MPU1

ATM230

MPU0

ATM230

18 A50016-D1109-K401-1-7618


3.2 ATM Switching network (ASN)The ATM switching network (ASN) comprises 2 ATM multiplexers/demultiplexers andthe ATM switching core module for ASN40 (ASMG16/16) (see Fig. 3.2).

The ATM multiplexer (AMX) consists of an ATM Multiplexer, type E (AMXE) and ASNController and clock generator (ACCG). The ACCG monitors the AMXE and provide theclock for the AMXE.

The ATM Multiplexer for ATM switching network (GMX) has up to 8 GMX:E multiplexers.In addition, the ATM Switching core module for ASN40 (ASMG16/16) is located in theATM switching network. A separate ACCG controller monitors the GMX and ASMG. Thepower supply unit PSAG is used for supplying power to the ASMG.

The central parts of the ASN (AMX, GMX, ASMG) are duplicated.

ATM Multiplexer, type E (AMXE)

The ATM multiplexer, type E (AMXE) is used in the SSNC as a concentrator stage tothe ASN. Up to 32 peripheral ports are possible between the AMXE and the peripheralunits – line interface card (LIC) or main processor unit (MPU). Each of the ports is con-nected with the AMXE via one or two STM1-equivalent ATM interfaces (each with207 Mbit/s). The ATM traffic from these peripheral units is concentrated by the AMXEinto up to 16 high-speed ATM links to the ASMG. In the opposite direction, the AMXEdistributes the ATM traffic from the ASMG to the different ATM ports of the peripheralunits. The interfaces between the AMXE and the peripheral units are implemented bymeans of electrical connections.

The AMXE itself is controlled via the ACCG.

ASN Controller and clock generator (ACCG)

The ACCG monitors and controls the ATM multiplexer, type E (AMXE). In addition, itsupports the clock pulse for the AMXE as well as for the peripheral units LIC and MPU.

The peripheral control platform (PCP) in the ACCG controls the configuration, testing,OAM and communications with the MPU. The hardware of the PCP is based on the IN-TEL 80386EX controller.

Communication with the MPU is performed using the internal transport protocol (ITP).

ATM Multiplexer for ATM switching network (GMX)

The GMX has the function of multiplexing sixteen 207-Mbit/s signals incoming from theperiphery and transferring them in the form of a 3.3-Gbit/s bit stream to the switchingnetwork (SN). In opposite direction the 3.3-Gbit/s signals have to be demultiplexed into16 serial 207-Mbit/s signals. The switching function ensures that the ATM cells are cor-rectly directed to the 16 outputs. A GMX:E chip is responsible for the multiplex function,while the switching network chip SE32/16B with an external multicast RAM is used forthe switching function. The GMX has an internal clock distribution system.

A50016-D1109-K401-1-7618 19



ATM Switching core module for ASN40 (ASMG16/16)

The module ASMG16/16 has two parallel connected SE-G16/8 switching network chips.The chips switch ATM cells at a data rate of 3.3 Gbit/s (an STM-16 equivalent) in a con-figuration with 16 inputs and 8 outputs. The data rate per port is 3.3 Gbit/s –physically connected in parallel on 4 lines, each with 828 Mbit/s. In addition to thetwo SE-G16/8 chips, the ASMG16/16 module has bipolar input and output drivers anda clock module.

Fig. 3.2 Structure of the ASN hardware

ASN

3,3 Gbit/s(STM-16)

GMXAMX

ACCG ACCGACCG

Powersupply

unit

ASMG16/16

AMXE GMX:E1

GMX:E8

LIC

MPU

207 Mbit/s(STM-1)

207 Mbit/s(STM-1)

3,3 Gbit/s(STM-16)

LIC

MPU

20 A50016-D1109-K401-1-7618


3.3 Line interface card (LIC)The line interface card (LIC) provides a E1/DS1 interface with 2 Mbit/s and 1.5 Mbit/srespectively. It converts the byte-oriented data stream on the STM side into a packet-oriented data stream on the ATM side, and vice versa.

The LIC operates 1:1 redundantly – i.e., both LICs receive ATM cells but only one LICsends this ATM cells to the ATM switching network (ASN). Each LIC has a common anda specific hardware part (see Fig. 3.3). The common part (which is identical for all LICs)contains the ATM part, the peripheral control platform (PCP), the power supply unit(PSU) and clock distribution. Specific to the LIC is the physical layer (PHY) for providingthe physical interfaces.

The individual functions of the different hardware parts are as follows:– The ATM part implements the ATM layer functions. It is logically divided into an up-

stream and a downstream part.– The peripheral control platform (PCP) is based on the INTEL 80386EX controller.

This controller is used for all LIC types and the ACCG. The internal communicationto the MPU is implemented with the aid of the ATM adaptation layer, type 5 (AAL5)and internal transport protocol (ITP).

– The power supply unit (PSU) generates the necessary voltages (3.3 and 5 V).– The clock generator monitors one of the two ASN clock inputs from the ACCGs and

supplies the clock generators for the physical layer and ATM parts.– The physical layer contains the physical layer functions and also the ATM adaptation

layer, type1 (AAL1).

Fig. 3.3 Structure of the LIC hardware

LIC

externallinks

ASNclock

ATM multiplexerASN

Crosschannel

V.24

physical layer ATM part

clockgenerator

powersupply

unit

peripheralcontrol

platform

upstream

downstream

A50016-D1109-K401-1-7618 21



3.4 ATM Bridge processor, type C (AMPC)The ATM bridge processor, type C (AMPC) is the interface between the ATM equipmenton the AMXE and the coordination processor 113C (CP113C). It converts the ATM datastreams to the CP communication mode. For functional purposes the AMPC belongs tothe SSNC, but it is located in the module frame of the CP.

The AMPC is realized as one module.

Like the other CP processors (BAP, CAP, IOC) the AMPC is connected to the bus forcommon memory (B:CMY), which provides it with access to common memory (CMY).

Pairs of AMPCs are operated in the CP in order to increase availability. An AMPC pairworks in working/spare mode - i.e., both AMPCs receive the same messages simulta-neously; messages are only sent by the active AMPC however.

In addition, the components of one AMPC are duplicated. Both halves operate mi-crosynchronously in order to detect hardware faults faster. One half operates as masterand generates data for the memory or external interfaces. The other half checks thatboth halves are running synchronously.

The AMPC hardware consists of the following major functional blocks (see Fig. 3.4):– Fiber optic transceiver type X (FOTX)

Each AMPC is connected to both halves of the duplicated AMXE via FOTX. TheFOTX modules are duplicated for redundancy reasons. If a FOTX or AMXE fails, theAMPC can still communicate with the ATM network via the other FOTX and AMXE.In the direction of the ATM network, the FOTX converts the electrical signals fromthe AMPC to optical signals, which it sends to the AMXE. The FOTX has a clock re-covery circuit for extracting the 207-MHz synchronization clock from the optical datastream.

– ATM interface chip ATM230Two ATM230 and the two FOTX modules implement the 207-Mbit/s interface to theATM network. The FOTX module generates a 207-MHz clock and sends it to the twoATM230. One of these chips is implemented as master, the other as checker. Sig-nals are exchanged between both ATM230 for synchronization purposes.

– Clock generatorThe clock generator is not duplicated. It is monitored by the interface controller to theB:CMY (AMPIFC) for the case that the clock frequency is not within the permissiblerange.

– Control unit (with microprocessor MC68EC040, with 50 MHz clock)Used for handling the programs and protocols to transfer messages across the ATMnetwork.

– Access and cycle control (PROAMP)These ASICs control bus and memory for the microprocessor and the interface chipATM230.

– Local memory unit (LMY) and flash EPROM (FEPROM)The size of the LMY is 32 Mbytes. The FEPROM memory has 4 Mbytes. Neithermemory unit is duplicated.

– Duplicate interface controller to the B:CMY (AMPIFC)This unit constitutes the interface to the bus for common memory (B:CMY). Its cen-tral function is the transmission of messages between local memory (LMY) and theB:CMY (and vice versa). In addition, the dynamically critical parts of the internaltransport protocol are implemented by means of two integrated processors in theAMPIFC.

22 A50016-D1109-K401-1-7618


Fig. 3.4 Structure of the AMPC hardware

AMPC

AMXE0 AMXE1

B:CMY1 B:CMY0

FEPROM

LMY

FOTX1

AMPIFC(Checker)

FOTX0

ClockGenerator

Control 0(MC68EC040)

AMPIFC(Master)

ATM230 0(Master)

ATM230 1(Checker)

Control 1(MC68EC040)

PROAMP1(Checker)

PROAMP0(Master)

A50016-D1109-K401-1-7618 23



3.5 ATM Interface module (ATM230)For the main processor (MP), ATM bridge processor, type C (AMPC) and message buff-er D (MBD) platforms, the ATM interface module (ATM230) is the functional unit whichpermits communication with all other system units, and the outside world, on an ATMbasis.

It forms the interface to the redundant ATM multiplexers, type E (AMXE) of the ATMswitching network, and for this purpose it has a duplicated high-speed interface(HSATM) for the internal ATM cell format with 207 Mbit/s.

All ATM cells are transmitted simultaneously by the module via both switching networkhalves. Received ATM cells are processed using redundant path combining. In thiscase, only the first valid cell with the expected sequence number is passed on, while thesecond cell from the other switching network half with the same sequence number is re-jected.

In order to ensure reliable processing of received cell bursts, the ATM230 has a bufferfor 100 cells.

The ATM230 is connected via a 32 bit bus architecture to the memory system of the rel-evant platform and operates as a coprocessor with intelligent DMA features parallel to,and independently of, the main processor.

The ATM230 allows two modules to be interconnected for microsynchronous operation(MP platform), and for use on the AMPC it also permits monitoring of the ATM interfaceon the transmit side in master/checker mode.

An important function of the ATM230 is to support and take over the realtime tasks forthe following signaling protocols:– internal transport protocol (ITP) on the basis of AAL3 and AAL5 for point-to-point

connections– integrated ring structures that are formed with the aid of ITP point-to-point connec-

tions– MTP level 1 and 2– ATM Adaptation Layer No.5 (AAL5)– ATM Adaptation Layer for signaling (SAAL)

3.6 Standalone STP ArchitectureThe SSNC can be used as a cost-effective standalone transfer point (STP) as no otherEWSD functional units (i.e. CP, SN, LTG) are required. In this configuration the AMPCis not deployed.

24 A50016-D1109-K401-1-7618


4 SSNC Software

4.1 Software architectureThe SSNC software is split up into different applications which may sometimes have toshare a main processor (MP). The software structure is as follows (see Fig. 4.1):– Virtual CPU (VCPU)– Service provision unit (SPU) inc. Service addressing– Recovery suite (RS)

Virtual CPU (VCPU)

A virtual CPU (VCPU) is a logical group of processes which have to fulfill a commonfunction on a main processor (MP), and which share a specific portion of the CPU timefor this purpose. This portion of the CPU time is specified via the VCPU budget, whichis defined in an MP-specific Load model.

This ensures that different functions which are executed on one MP always receive afair portion of the CPU time and that processes of one function cannot completely ex-clude processes of a different function.

Example: Maintenance and administration processes run under the VCPU ’OAM’. MTPnetwork management processes are assigned to the VCPU ’Network Management’,while MTP Level 2 and Level 3 functions run under the VCPU ’Protocol Handler’.

Service provision unit (SPU)

The service provision unit (SPU) is a unit comprising processes and data modules witha strong relationship of functions. The unit enhances safety and communications be-cause data are exchanged only at operating system level between SPUs. The SPU isdesigned in such a manner that it can be used platform-transparently. It can even beused simultaneously on several platforms if similar tasks need to be processed in par-allel.

Recovery suite (RS)

Within an SPU processes can be compiled in a recovery suite, which can be started in-dividually without impairing the operation of the other software. With the recovery suite(RS) one can restrict the effects of software errors.

Service addressing

Since the SPU design units can be reproduced on different processing platforms forloadbalancing reasons, a system function is required for assisting in communicationsbetween two SPUs. This function is known as service addressing.

Services provided by an SPU are announced to the system. If an SPU wishes to com-municate with another SPU it calls the operating system. The calling SPU is given a uni-versal buffer ID with which the communication to the called SPU is performed. Thecommunication can take place by sending messages or by calling remote procedures.

A50016-D1109-K401-1-7618 25



Appropriate communication mechanisms enable the following– increased fault tolerance:

If a processing platform is taken out of operation, both messages and remote proce-dure calls can be forwarded to another platform by additionally calling the serviceaddressing function.

– more equal distribution of the load in the system:If the processing platform is overloaded, the load can be diverted to another platformby regularly calling up the Service Addressing function.

Fig. 4.1 Arrangement of software structure elements on a processing platform

Application program system (APS)

An application program system (APS) is the combination of all sub-APSs. A sub-APSsis the collection of all service provision units (SPU) belonging to a single processing plat-form (e.g. MP:OAM).

Processing platform 1

SPU m

SPU 1

Operating system

Communication only viathe operating system

Communication with otherprocessing platforms

Data moduleProcess

Processing platform n

RS 1

ProcessProcess

26 A50016-D1109-K401-1-7618


4.2 Software unitsThe following software units are distinguished in the SSNC (see Fig. 4.2):– Signaling link termination (SLT)– Signaling manager (SM)– Statistics support platform (STATS)– Operation, administration and maintenance platform (OAM)

In addition to its actual software functions, every main processor (MP) contains the op-erating system (OS), the internal transmission protocol (ITP) and the driver software forthe ATM interface module ATM230.

Fig. 4.2 Software function units in the SSNC

MTP level 1MTP level 2SAALMTP level 3 (MH)SCCP GTTMTP/SCCP MEASHPDBDBMS

ASN

OS ITP ATM230

MTP level 3 (NM)SCCP (SCMG)MTP/SCCP MTCHPDBDBMS

OS ITP ATM230

SLT

SM

MTP/SCCP ADMINMTP/SCCP MEASMTP/SCCP MONITMTP/SCCP MTCDBMSOMAP

OS ITP ATM230

OAM

207 Mbit/s

measurementcollectionSTATS

SSNC

207 Mbit/s

207 Mbit/s

207 Mbit/s

to LIC

to MBD

to CP

A50016-D1109-K401-1-7618 27



The main processor (MP) can operate as a software function SLT, as Signaling man-agement (SM), as Statistics support platform (STATS), or as MP:OAM platform. De-pending on the application, an MP can be assigned a particular Load model from anumber of predefined load models. In accordance with the selected load model, theavailable processor time is divided among the individual virtual CPUs in order to meetthe individual function-dependent run-time requirements.

Signaling link termination (SLT)

The SLT is a software package containing the following functions:– MTP level 1 functions (message transfer)– MTP level 2 functions (message safeguarding)– Signaling ATM adaptation layer (SAAL)– MTP level 3 functions (message handling, MH, user part allocation, and parts of the

network management)– SCCP routing for incoming SCCP messages (inc. global title translation, GTT)– MTP/SCCP measurements (MEAS)– Database functions (HPDB and DBMS)– Screening functions

Depending on the performance requirements for the network node, the SSNC can beconfigured with up to 47 MP:SLTs. Depending on the link load up to 60 conventional sig-naling links (64 kbit/s / 56 kbit/s) or two high speed signaling links (2 Mbit/s / 1.5 Mbit/s)can be connected to each MP:SLT.

Signaling manager (SM)

The SM is a software package that contains the following SSNC management functions:– MTP level 3 network management (NM)– SCCP management (SCMG)– MTP/SCCP maintenance (MTC)– Database functions (high performance database, HPDB and database management

system, DBMS)

There is exactly one MP:SM in an SSNC.

Statistics support platform (STATS)

In addition to the two platforms MP:SLT and MP:SM, the SSNC also contains the plat-form MP:STATS. The SSNC measurement data are collected by the MP:STATS, for-matted and sent at intervals of 5 or 15 minutes to the MP:OAM, which in turn writes thedata to the local hard disk. From there the data records are transferred to the relevantprocessing centers.

28 A50016-D1109-K401-1-7618


Operation, administration and maintenance platform (OAM)

The platform MP:OAM, which only exists once in the SSNC, only performs OA&M tasks.It contains the following functions:– MTP/SCCP administration (ADMIN)– MTP/SCCP measurements (MEAS)– MTP/SCCP monitoring and alarming (MONIT)– MTP/SCCP maintenance (MTC)– MTP/SCCP database management system (DBMS)– Operations, maintenance and administration part (OMAP)

Due to this separate OAM platform and the fact that it performs the functions listedabove, the SSNC can be operated, administered and maintained independently of theCP. The database management system (DBMS) is the MTP/SCCP master database.From there, SS7 relevant semipermanent and transient data in the EWSD database ofthe CP are updated when necessary.

The operations, maintenance and administration part (OMAP) is also located on theOAM platform. The ITU-T Q.751.n series of recommendations defines object modelscontaining managed objects which allow to administer SS7 data - e.g. routing data,availability of SS7 managed items, measurements results etc. - via the Q3 interface.Such Q3 models are provided for the following functions:– MTP (Q.751.1)

(see description Signaling System No.7 (SS7))– SAAL signaling links (Q.751.1)– MTP monitoring and measurements (Q.751.1 main body and Annex E)

(s. chapter 7.1)– MTP accounting and verification (Q.751.3)– MTP screening (Q.751.1 and adaptation of Q.751.3)– MTP route verification test - MRVT (Q.751.1 main body and Annex F)– SCCP (Q.751.2)

(see description Signaling Connection Control Part (SCCP))– SCCP monitoring and measurements (Q.751.2 and proprietary improvements)

(see description Signaling Connection Control Part (SCCP))– SCCP accounting and verification (Q.751.4)

A50016-D1109-K401-1-7618 29



4.3 Load modelTo support the concept of the virtual CPU (VCPU) every main processor (MP) needs aload model which defines the budgets for the VCPUs on this MP. In order to be able tomake optimum use of the available processor capacity on an MP in accordance with thefunctions that are being executed on it, several different load models are defined, fromwhich the load model management assigns to each MP the most suitable model for thefunction of the MP.

In order to achieve the maximum possible performance of the various functions, the loadmodel management provides the following functionalities:– Easy integration of a load model for an MP platform into the system.– Automatic adjustments to the VCPU budgets due to time-limited events so as to re-

tain the performance and delay time requirements for situations of this kind.– Changes to current load model data without the MP platform having to perform a re-

covery.

All load model data are centralized in a service provision unit (SPU), which exists onceon each MP platform.

30 A50016-D1109-K401-1-7618


5 FeaturesNetwork consolidation requires powerful and scalable signaling nodes. Deregulation ofnational telecommunication markets results in a multitude of networks with frequent net-work interworking. Besides superior performance and flexibility the SSNC therefore of-fers a number of new and innovative features:– SS7 Screening– SS7 Accounting– High-Speed Signaling Links (HSL)– Multiple SS7 Networks– Global Title Translation (GTT)– MTP Route Verification Test (MRVT)– Extended load sharing– SS7 Traffic structure measurement

5.1 SS7 ScreeningSupervision of the message flow, especially in deregulated networks, calls for the useof screening (firewall/policing) in Signaling System No. 7 (SS7). The SS7 Screening fea-ture ensures that only authorized signaling traffic is forwarded. Unauthorized traffic is re-jected and can be registered. The screening function has no effect on the link throughputcapacity.

The signaling system network control (SSNC) supports the following SS7 screeningfunctions:• Screening in the message transfer part (MTP)• Screening in the signaling connection control part (SCCP)

5.2 SS7 AccountingThe SS7 Accounting feature (based on ITU-T Q.751) is used for usage metering regard-ing Signaling System No. 7 (SS7) traffic between different operators. Usage meteringdata can be recorded for messages in the message transfer part (MTP) as well as formessages in the signaling connection control part (SCCP).

MTP Accounting records the traffic volume of transferred SS7 messages (number ofmessages and number of bytes). Sent SS7 messages are recorded by MTP AccountingVerification.

SCCP Accounting enables operators to determine what traffic is using the SCCP globaltitle translation (GTT) function in the own signaling transfer point (STP).

A50016-D1109-K401-1-7618 31



5.3 High-Speed Signaling Links (HSL)The High-Speed Signaling Links (HSL) feature increases the bandwidth between SS7network nodes. High-speed signaling links can, for example, be used to set up a verypowerful SS7 overlay network consisting of (fully or partially meshed) standalone signal-ing transfer points (STP). The signaling end points (SEP) of the SS7 network are con-nected to the assigned mated pairs of standalone STPs via conventional signaling links.High-Speed Signaling Links can also be used to connect the service control points(SCP) of an intelligent network (IN) to the standalone signaling transfer points (STP).

5.4 Multiple SS7 NetworksThe Multiple SS7 Networks feature expands the range of network planning options inderegulated markets. With this feature, up to 32 Signaling System No. 7 (SS7) routingdomains (internal networks) can be administered in one network node. This means thata node can be connected to up to 32 separate signaling networks.

The Multiple SS7 Networks feature is fully compatible with ITU-T SS7 standards, i.e. itis transparent for all SS7 protocols.

5.5 Global Title Translation (GTT)Global Title Translation (GTT) is a powerful function for translating the address datacontained in SS7 messages from users of the signaling connection control part (SCCP).This function allows SCCP users to use a centrally administered address system that isindependent of the MTP network (e.g. special service numbers).

Global Title Translation is used, for example, in the mobile radio network in connectionwith international roaming and in the intelligent network (IN) for addressing the servicecontrol point (SCP).

5.6 MTP Route Verification Test (MRVT)The MTP Route Verification Test (MRVT) feature is a management function of SignalingSystem No. 7 (SS7). This feature is used to verify the routing of signaling traffic betweenan originating point and a destination point in the SS7 network. The test covers all rele-vant routing tables of the message transfer part (MTP). The test function works in a de-centralized manner. Test commands are distributed to the nodes in the SS7 network.Each network node checks the routes that pass through it, leading to the destinationnode. This check covers, among other things, compliance with maximum length and ab-sence of loops.

32 A50016-D1109-K401-1-7618


5.7 Extended load sharingA distinction is made between load sharing for the message transfer part and for the sig-naling connection control part (SCCP).

MTP load sharing

Load sharing ensures that the signaling traffic is distributed as evenly as possible overall signaling links and signaling transfer points (STP) in the network. In the case of MTPload sharing of the SSNC, up to eight possible routes can be created per destination,and these are divided into load sharing groups, i.e. routes with equal priority.

The signaling traffic can be distributed over the first two signaling linksets of a load shar-ing group. If one route (linkset) fails, this traffic is diverted to the next signaling link setof the same load sharing group. Only when all routes of one particular load sharinggroup have failed is the traffic transferred to the next load sharing group.

In addition the SSNC optionally provides an extended loadsharing algorithm in order tocompensate for an uneven SLS distribution in incoming message streams. Dependingon network configuration and traffic characteristics it is thus possible to distribute outgo-ing traffic over all available links of a linkset even if the SLS addresses only a subset ofthem. An additional advantage of this option is that it can eliminate the need for detailedagreements between operators regarding traffic distribution in network interconnection.

SCCP Loadsharing

In the SCCP, load sharing between main and backup translators is possible, as well asload sharing between subsystems. Remote SCCPs can be combined to form translatorgroups consisting of two main nodes and two backup nodes in which the same transla-tions are performed. If a main node fails, the backup node takes over its task at once.Load sharing between the two main or backup translators is possible.

Remote subsystems can be combined to form subsystem service groups consisting ei-ther of a main subsystem and a backup subsystem or of two main subsystems on whichthe same service is available.

If a main subsystem fails, switchover to the backup subsystem takes place at once. Loadsharing via the main subsystems is possible.

A50016-D1109-K401-1-7618 33



5.8 SS7 Traffic structure measurementThe feature SS7 traffic structure measurement evaluates the message flow in theSSNC. The data of every nth message (n=trace rate) is traced. The data in this file canthen be evaluated by the operator, and this statistical evaluation can be used to verifythe network design. For example, the ratio of transit signaling traffic to terminating sig-naling traffic can be determined.

5.9 Additional featuresA number of additional features extend the SSNC functionality:– MTP networks can support destination point codes (DPC) and originating point

codes (OPC) with a length of 14 bits (ITU-T) or 24 bits (ITU-T/ANSI, for national ap-plication).

– Enforcement of message length compatibility according to ITU-T Q.701 §7.2.5.– In the event of a lengthy route overload (this could be due to a routing loop) the MTP

checks whether the OPC of received messages and of messages that are to be senton the overloaded route corresponds to its own point code. In this case the messageis rejected and counted as a routing error (“routing loop”). This information allowsthe operator to take appropriate counter-measures.

– If a message is transmitted on the same signaling link set as the one on which it wasreceived (“ping-pong loop”), this message is rejected and a TFP concerning the des-tination is sent to the adjacent node, with the result that the loop is removed withoutany intervention by the operator.

34 A50016-D1109-K401-1-7618


6 SSNC PerformanceThe SSNC uses the main processor (MP) as signaling manager (MP:SM), signaling linktermination (MP:SLT), STATS platform (MP:STATS) and OA&M platform (MP:OAM).

Technical Data

Number of signaling manager (SM) per node: 1

Max. number of signaling link termination (SLT) per node: 47

Transmission rate of a digital signaling link: 64 kbit/s56 kbit/s

Transmission rate of a high speed signaling link: 1 920 kbit/s1 536 kbit/s

Number of different network indicators:Number of SS7 networks:

432

Maximum possible number of signaling links per SLT: 60

Number of high speed signaling links per SLT: 2

Number of possible signaling links per node: 1 500

Number of possible link sets per node: 1 024

Number of possible signaling links in a signaling link set: 16

Number of possible routes in a route set: 8

Number of possible route sets per node: 4 096

Number of possible routes via a link set: 2 048

Number of trunk groups per node: 4 096

Number of trunk groups per destination point code (DPC): 64

Number of possible trunks per node: 120 000

Number of possible trunks per trunk group: 4 096

Number of configurable code points (SCCP GTT): up to 16 384

Message throughput per node(average MSU length: 33 byte):SEP:STP:SEP/STP:

100 000200 000200 000

A50016-D1109-K401-1-7618 35



GTT throughput per node(average MSU length: 100 byte): 40 000

Signaling traffic load per signaling link:normal load:maximum load:overload (max. for 3 sec):

0.4 Erl0.8 Erl1.0 Erl

MTP message length (including signaling information field, SIF, andservice information octet, SIO)maximum (64 kbit/s):maximum (broadband links, high speed signaling links):

273 Byte4 096 Byte

Downtime:of a signaling channel (only the hardware):of a signaling channel (hardware, software, procedure error, O&Mactivities):total system downtime):

0.15 min/year

1.6 min/year0.06 min/year

STP message transfer time (delay) fulfill the requirements of ITU-TQ.706GTT transfer time (delay) fulfill the requirements of ITU-T Q.706

36 A50016-D1109-K401-1-7618


7 SSNC Operation, administration and mainte-nanceSSNC operation, administration and maintenance can be performed via the separateMP:OAM platform. A distinction is made between:– Operations, maintenance and administration part (OMAP)– Administration– Maintenance

7.1 Operations, maintenance and administration part (OMAP)The main parts of the OMAP functions handled in the SSNC are located in the functionunit MP:OAM.

The operations, maintenance and administration part is divided into:– MTP Monitoring– SCCP Monitoring (for details see description Signaling Connection Control Part

(SCCP))– MTP Measurements– SCCP Measurements (for details see description Signaling Connection Control Part

(SCCP))– MTP Route Verification Test

MTP Monitoring

Monitoring delivers information (e.g. alarms) about specific events (e.g. link failures) inSS7 networks after a configurable smoothing period (delay) to system alarming or theNetManager. This smoothing period is used to prevent that the system is flooded byshort term alarms. In the event of failures of link sets, links or route sets the alarms areheld back for up to 10 minutes depending on the time set for the object.

SS7 events (e.g. link inhibiting) are analyzed by Monitoring and forwarded directly viathe Q3 interface to the NetManager. Events and alarms which are to be reported bymonitoring are defined in ITU-T Q.752.

E.g. a link failure will be recognized by the MTP level 2 and reported to network man-agement. Network management informs MTP maintenance which updates the link statein the database management system (DBMS) and informs monitoring about the statechange (see Fig. 7.1).

Monitoring updates the alarm state (attribute in the DBMS) for this link via the centralsystem alarming function. System alarming then forwards the corresponding alarm no-tification via the Q3 interface to the NetManager. The notification specifies the failurereason as determined by MTP Maintenance.

A50016-D1109-K401-1-7618 37



Fig. 7.1 Position of MTP Monitoring in the OA&M

MTP Measurements

Measurements report the frequency of specific events in SS7 networks.

The MTP measurement functionality is distributed on MP:OAM, on MP:SM, all MP:SLTand on coordination processor (CP). The functions for administrating the measurementsare located on the MP:OAM for the Q3 commands from the NetManager and on the CPplatform for MML-commands and Q3 Get commands for the traffic structure measure-ments.

The MTP measurements are based on ITU Q.751.1 / Q.752 and are defined in the MTPobject model. The MTP measurements Q3 commands originate from NetManager, areadministrated according to the Q.822 standard, and are processed at the MP:OAM.

MP:OAM

MP:SM

MP:SLT

level 2,signaling ATMadaption layer

MTP maintenance

MTP maintenance

network management

MTP monitoring

Q3 platform

NetManager

systemalarming

DBMS

38 A50016-D1109-K401-1-7618


On the MP:SLT platform and MP:SM platform measurements data are continuously col-lected by the MTP functions and recorded in the measurement tables of the high perfor-mance data base (HPDB). The measurement counters in these tables are incrementedby network management, message handling and signaling ATM adaptation layer-(SAAL) applications. The measurement data from the HPDB measurement tables is de-livered to STATS on the statistics support platform MP:STATS. Due to performance rea-sons there exists an own main processor (MP) handling exclusively this functionality.STATS collects measurement data received from the providers, formats them andsends them to the Q3 platform on the MP:OAM, which in turn writes the data to the localhard disk. The files and data records are transferred from there to the relevant process-ing centers.

Fig. 7.2 below shows the Measurement interfaces within the main processor (MP) andto the NetManager.

Fig. 7.2 Messageflow of the MTP-Measurements

MP:OAM

MP:SLT /MP:SM

Q3-Platform

NetManager

DBMS

MP:STATS

STATS

MTP-Measurements

A50016-D1109-K401-1-7618 39



7.2 AdministrationThe Administration functions are implemented on the MP:OAM. The administration ofthe MTP is in accordance with Q.751.1, Q.2751.1 and Q.822.

The MTP administration provides the Q3 interface for basic MTP object classes (i.e. theMTP signaling network elements), object classes for measurements, for MTP screening,for MTP accounting and for the MTP route verification test (MRVT).

The function of the SSNC administration is to accept user requests for all administration-specific SSNC functions, to perform the maximum possible number of plausibilitychecks on user inputs, to enter data in the master database as well as reading data outof the database.

The software for the SSNC administration comprises the following (see Fig. 7.3):– MTP administration– SCCP administration:

(see description Signaling connection control part (SCCP))– Monitoring and alarm administration– Measurement administration

Fig. 7.3 Software structure of the SSNC administration

MP:OAM

NetManager

database

Q3 platform

MTP administrationSCCP administration

Monitoring and alarm administrationMeasurement administration

40 A50016-D1109-K401-1-7618


MTP administration

The MTP administration in the SSNC controls the handling of the input and output com-mands entered by the operating personnel via the Q3 interface of the NetManager. Q3requests enter the system from the OAM platform and are forwarded to the MTP admin-istration.

All MTP administration functions run on the MP:OAM and affect the other MP platforms;no administration is required in the other processors (line interface card, LIC, and ATMbridge processor, type C, AMPC).

The following administration functions are available for objects that are defined in theSSNC object model:– creation/modification/cancellation/display of the signaling network elements

These functions enable the signaling network to be modified. The signaling networkelements are the objects in the object model and represent, e.g., signaling links.

– configuration of signaling network elements– Testing of signaling network elements

Monitoring and alarm administration

Monitoring and alarm administration configures the parameters for the individual han-dling of alarms and messages. This includes also the specification of the destination(e.g. NetManager) where alarms and messages have to be routed to.

Measurement administration

The task of the measurement administration is to create and cancel measurement ob-jects, etc. This means that the measurement objects are entered by the measurementadministration onto the database management system (DBMS) and the high perfor-mance database (HPDB).

A50016-D1109-K401-1-7618 41



7.3 MaintenanceThe SSNC maintenance is responsible for evaluating the impact of hardware statechanges on SSNC functions and to trigger the appropriate handling. The maintenancereceives messages from network management about state changes of SSNC elements,transforms the states according to Q.704 used by network management to those ac-cording to Q.751.1 to be stored in the database management system (DBMS) and in-forms monitoring about the state changes. Maintenance is responsible for providing thepermanent virtual channel addressing data for the ATM230 on the main processors aftera reset after recovery or on demand. Furthermore it is responsible for building, deletingand verifying the level 1 paths (through the switching network (SN)) connected at aline/trunk group (LTG).

All maintenance functions are divided into four levels:

The levels 1 - 3 are processor-oriented. They mainly concern actions specific to individ-ual functions (switchover, loading, activating, etc.).In contrast, the level 4 (maintenance managers) effect a much larger area. It possesslittle or no information as to which specific actions have to be carried out (this is the func-tion of the maintenance scheduler). Instead, the maintenance managers know the rela-tionships between the processors, evaluate their states in the database and perform thecommunication between the maintenance software running on different processors.

4th level Maintenance manag-ers

Global coordination and supervision of actions.Handling of concurrent requests

3th level Maintenancescheduler

Execution of specific actions accordingto the object-specific tables

2nd level Programs Execution of specific action1st level Hardware/data

42 A50016-D1109-K401-1-7618


The following maintenance functions are distinguished:– Configuration– Error handling– Diagnosis– Routine testing– Audits– Recovery

Configuration

The configuration processes the status changes of all hardware units. It is responsiblefor maintenance of the statuses and for consistency of the device database. In addition,it coordinates the various requests from other managers, such as the managers for di-agnosis or routine testing. It is the control element for all alarm events and forwardsalarm information to the maintenance control interface.

Error handling

The error handling function is the first function activated for all spontaneous events inthe hardware. Using the diagnosis function, it verifies and locates errors and requestsstatus changes from the configuration function.

Diagnosis

Diagnosis is used to localize errors that occur in units that are not in operation. The di-agnosis function is used both by operating personnel as well as by the error handlingfunction. It provides the operating personnel with access to the out of service units sothat the error information can be read.

Routine testing

Routine tests run in the background and check the operability of units that are runningand units that are not in operation. Units which are administratively blocked are notchecked.

Audits

An SSNC maintenance audit verifies the consistency of transient data in the high per-formance database (HPDB) on the signaling manager as master data and in the data-base management system (DBMS) on the MP:OAM. Inconsistencies result in triggeringrepair actions and reports via the audit sequencer.

A50016-D1109-K401-1-7618 43



Recovery

After high level recoveries of the MP:OAM and the MP:SM a post recovery handling isstarted on the MP:OAM to find and continue aborted SSNC maintenance jobs and to up-date the transient signaling managed object instance states in the DBMS:MTP. After re-covery of the MP:SLT the channel data in the ATM230 for user node interface links andAAL5 connections will be reestablished, if the ATM230 was reset during the recovery.

The SSNC has the following recovery levels:– PROREC

PROREC on MP:SLTRecovery level PROREC is performed fast enough so that no timeout and conse-quently no route failure and no message loss occurs. Timers which may have beenactive as the recovery occurred are restarted. Message handling is restarted withoutexternal trigger and link supervision is executed as if no interruption had taken place.Failed links are reported to network management. There are no specific measuresto compensate the effects of a PROREC of an MP:SLT.PROREC on MP:SMThere are no specific measures to compensate the effects of this recovery level ofan MP:SM. The network management process, if affected, must ensure that anytask interrupted by the PROREC, is restarted. The SSNC maintenance function onthe signaling manager (SM) makes sure that no state changes have been lost.PROREC on MP:OAMThe effected processes must ensure that tasks interrupted by this recovery level arerepeated. Messages without acknowledgement are repeated. The SSNC mainte-nance function on the OAM makes sure that no state changes of hardware ele-ments, communication capabilities or network elements have been lost.

– FULLRECFULLREC on MP:SLTThe recovery level FULLREC of an signaling link termination (SLT) is handled as arecovery level LOADREC.FULLREC on MP:SMNetwork management performs audit checks to ensure that distributed data arecompatible and that failed links are taken into restoration. The SSNC maintenancefunction on the signaling manager (SM) makes sure that no state changes havebeen lost.

FULLREC on MP:OAMThe recovery level FULLREC is performed locally without disturbing other proces-sors. No external measures are necessary. Interrupted measures triggered by exe-cuted Q3 commands are reestablished.

– LOADREC3The recovery level LOADREC3 will format all memory areas and may be executedonly during manual activation of the unit.

– LOADREC Scope platform (LOADREC2)The recovery level LOADREC2 includes a selective memory formatting (withoutsymptom storage area) and may be executed due to recovery escalation.LOADREC on MP:SLTThe recovery level LOADREC of the MP:SLT is supervised by hardware mainte-nance. The startup info service on MP:OAM informs SSNC maintenance on theMP:OAM and network management on MP:SM about the beginning of the recovery.The network management evaluates the affected links and performs the measures

44 A50016-D1109-K401-1-7618


on failure: changeover and report to SSNC maintenance. The network managementalso reacts in the appropriate way if the SLT affected is the only one available. TheMTP routing tables are downloaded to new active SLT platform under network man-agement control. After the end of recovery, the SLT reaches the active state again.Startup info service informs SSNC maintenance. SSNC maintenance checks wheth-er the affected SLT can communicate undisturbed with all other platforms, and if so,it informs network management to restart restoration of the signaling links.LOADREC on MP:SMThe recovery level LOADREC of the MP:SM is supervised by hardware mainte-nance on the MP:OAM. The startup info service informs SSNC maintenance onMP:OAM about the beginning of the recovery. SSNC maintenance detects that theMP is the SM. If the signaling manager (SM) is out of service for more than 10 min-utes, all signaling links are deactivated. Whenever the SM is not available or not ac-tive, incoming Q3 commands are stored semipermanently and then executed whenthe SM is available again. During the recovery level LOADREC, the network man-agement performs an MTP restart for all networks which compensates any datalosses. All links will briefly go out of service.LOADREC on MP:OAMThere is no LOADREC scope platform for the MP:OAM.

– LOADREC System :LOADREC system is the normal startup of the SSNC. The network managementperforms an MTP restart.

Failure of LIC, ASN and AMXE

Reaction on state changes of hardware platforms:– LIC failure

When a line interface card (LIC) fails, all signaling links routed via this LIC fail as longas the LIC is out of service. After reactivation of the LIC the affected links are reac-tivated automatically.

– ASN failureWhen the ATM switching network (ASN) fails, all main processors (MP) are isolatedand all links fail immediately. This situation is reported to and treated by SSNC main-tenance as a total failure of SM and all SLT (and thus of all links) at the same time.Monitoring is informed about the link failures. After reactivation of the ASN, reactiva-tion of all MPs is reported to SSNC maintenance and handled accordingly.

– AMXE failureIf MP:OAM and MP:SM are isolated from the rest of the system (e.g. as a result ofdouble failure (side 0 and side 1) of the ATM multiplexer to which they are connect-ed), this does not initially have any effects on the other main processors (MP). Theseprocessors can communicate as before, so no link fails immediately. This situationhowever is reported to and treated by SSNC maintenance as a total failure of signal-ing manager (SM) and all signaling link terminations (SLT) (and thus of all links) atthe same time. Monitoring is informed. After reactivation of the AMXE, reactivationof all main processors is reported to SSNC maintenance.

A50016-D1109-K401-1-7618 45



Operating states of the hardware

The operating state of the hardware components is defined by three attributes:– the administrative state

The operating personnel can change administrative states. The system may issuewarnings for certain changes in states in some cases but always permits changes.Administrative states are stored semipermanently. The following administrativestates exist: not equipped (RSV), reserved (RES), maintenance blocked (MBL), up-grade (UPG), unblocked (UBL).

– the error stateThe error state indicates whether a hardware unit is faulty. Faults for which the hard-ware unit has completely failed are distinguished from faults for which the hardwareunit can still function. The following statuses exist: clear of faults (CLR), faulty (FLT),unavailable (UNA).

– the system stateThe system state is administered by the configuration function according to internaland external events. The operating personnel can only change a system state duringswitchover if requested. The system state is critical transient data. The system statecan have the following values: not accessible (NAC), out of operation (OOP), in test(TST), initialisation incomplete (INI), standby (STB), active maintenance (ACM), ac-tive (ACT).

Operating states are visible to the craft. The division into three states corresponds to thedifferent activities of the craft: administration tasks, hardware fault handling and config-uration. The craft can configure a unit to a specific administrative state at any time. Thesystem automatically attempts to provide the operating state offering as much serviceas possible. The administrative state is not changed by the system. Thus, after a repaircycle, a unit is reconfigured to its original state.

46 A50016-D1109-K401-1-7618


8 SSNC DatabaseIn the SSNC an object-oriented data model is used. The data are stored on different plat-forms.

Two databases are implemented:– Database management system (DBMS)– High performance database (HPDB)

Database management system (DBMS)

The database management system (DBMS) in the SSNC is the master database for themessage transfer part (MTP), the signaling connection control part (SCCP), etc. TheDBMS is located on the OAM platform, the signaling manager (SM) and the signalinglink terminations (SLT). All MTP data (level 1 - level 3) are administered and stored inthe master database of the OAM platform. As a result, the data are loaded exclusivelyfrom this platform to the platforms SM and SLT.

High performance database (HPDB)

This database allows very fast access by applications to the required data.

The main reasons for designing a high performance database are the runtime critical re-quests of the MTP functions (e.g., routing, network management, user allocation).Therefore the HPDB:MTP is closely connected to the MTP functions on SLT and SM.

In the following paragraphs only the MTP part of the HPDB is described. For more de-tails on the SCCP part please refer to the description Signaling Connection Control Part(SCCP).

The high performance database is located on software platforms SM and SLT. On theSM the HPDB contains tables for network management. On the SLT the HPDB containstables for e.g. routing. The tables of the HPDB contain both, transient (e.g., link status,counters) and semipermanent data. The semipermanent allocation data (trunkdata) isloaded from the coordination processor (CP) to the signaling manager (SM). All othersemipermanent data of the HPDB is derived from the database management system oneach platform directly.

Access to HPDB data on SM is possible only via access procedures. On the signalinglink termination (SLT), direct access to HPDB data is possible for all applications underthe protocol handler (mainly message handling).

Changes of HPDB data are caused by events from the SS7 signaling network. TheHPDB is also updated in case of startup or configuration and in case of NetManager in-put via the DBMS.

Documents

SSNC Introduction