EWSD System Description EWSD - System Description 1.0 Introduction : The Department of Telecommunications had announced ambitious plans for the addition of 7.5 million lines to the existing 5.8 million by the end of the 8th plan (1992-97) as compared to only 3.2 million in 1982-92. Consequent upon delicensing of the Telecom. equipment and throwing it open to foreign investments, six new technologies were planned to be validated. These foreign suppliers set up their validation exchanges, each of 10,000 lines capacity (including two RSUs of 2K each), at different places, e.g. EWSD of Siemens (Germany) at Calcutta, AXE-10 of Ericsson (Sweden) at Madras, Fetex-150 of Fujitsu (Japan) at Bombay, OCB-283 of Alcatel (France) at Delhi etc. EWSD is one of the technologies selected for TAX and is also the technology for Intelligent Network and Mobile Communication. This article gives a general introduction to the EWSD system, its features, architecture and facilities. 2.0 System Features : EWSD Digital switching system has been designed and manufactured by M/s Siemens, Germany. The name is the abbreviated form of German equivalent of Electronic Switching System Digital (Electronische Wheler Systeme Digitale). EWSD switch can support maximum 2,50,000 subscribers or 60,000 incoming, outgoing or both way trunks, when working as a pure tandem exchange. It can carry 25,200 Erlang traffic. It is claimed that the ALTTC/SW-II 1/26 F11-Sys/01.10.2005
Transcript
EWSD System Description
EWSD - System Description
1.0 Introduction :
The Department of Telecommunications had announced ambitious plans for the addition of 7.5 million lines to the existing 5.8 million by the end of the 8th plan (1992-97) as compared to only 3.2 million in 1982-92.
Consequent upon delicensing of the Telecom. equipment and throwing it open to foreign investments, six new technologies were planned to be validated. These foreign suppliers set up their validation exchanges, each of 10,000 lines capacity (including two RSUs of 2K each), at different places, e.g. EWSD of Siemens (Germany) at Calcutta, AXE-10 of Ericsson (Sweden) at Madras, Fetex-150 of Fujitsu (Japan) at Bombay, OCB-283 of Alcatel (France) at Delhi etc.
EWSD is one of the technologies selected for TAX and is also the technology for Intelligent Network and Mobile Communication. This article gives a general introduction to the EWSD system, its features, architecture and facilities.
2.0 System Features :
EWSD Digital switching system has been designed and manufactured by M/s Siemens, Germany. The name is the abbreviated form of German equivalent of Electronic Switching System Digital (Electronische Wheler Systeme Digitale). EWSD switch can support maximum 2,50,000 subscribers or 60,000 incoming, outgoing or both way trunks, when working as a pure tandem exchange. It can carry 25,200 Erlang traffic. It is claimed that the system can withstand a BHCA of four million with CP-113C in case of EWSD Powernode (two million in case of EWSD Classic). However, the effective dynamic call set up performance depends on the available features and the actual call-mix. It can work as local cum transit exchange and supports CCS No.7, ISDN and IN and V5.X features.
3.0 System Architecture :
The main hardware units of an EWSD switch are as under:-
(1) Digital line unit (DLU) - functional unit on which subscriber lines are terminated.
(2) Line/Trunk Group (LTG) - Digital Trunks and DLUs are connected to LTGs.
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EWSD System Description
The access function determined by the network environment are handled by DLUs and LTGs .
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DLU
DLUCC
LTG
GP
LTG
GP
Common channel signaling/ Signaling System Network Control
CCNC/SSNC
Access
Coordination
CPSYPSYPC
MBMBC
CCG
EM
OMTSGC
Switching Network
Distributed controls in EWSD
EWSD System Description
(3) Switching Network (SN) - All the LTGs are connected to the SN which inter connects the line and trunks connected to the exchange in accordance with the call requirement of the subscribers. CCNC and CP are also connected to SN.
(4) Coordination Processor (CP) - It is used for system-wide coordination functions, such as, routing, zoning, etc. However each subsystem in EWSD carryout practically all the tasks arising in their area independently.
(5) Common Channel Signaling Network Control (CCNC) Unit or Signaling System Network Control (SSNC)- This unit functions as the Message Transfer Part (MTP) of CCS#7. The User Part (UP) is incorporated in the respective LTGs.
Block diagram of EWSD is given on previous page. It also shows that the most important controls are distributed throughout the system. This distributed control reduces the coordination overheads and the necessity of communication between the processors. It results in high dynamic performance standard.
For inter-processor communications , 64 kbps semipermanent connections are set through SN. This avoids the necessity for a separate interprocessor network.
3.1 Digital Line Unit (DLU)
Analog or Digital (ISDN) subscribers, PBX lines or V5.1 interface are terminated on DLU . DLUs can be used locally within the exchange or remotely as remote switch unit , in the vicinity of the groups of subscribers.
DLUs are connected to EWSD sub-systems via a uniform interface standardized by CCITT, i.e., Primary Digital Carrier (PDC) to facilitate Local or Remote installation. A subset of CCS# 7 is used for CCS on the PDCs.
One DLU is connected to two different LTGs for the reasons of security. A local DLU is connected to two LTGs via two 4 Mbps (64 TSs) links, each towards a different LTG. In case of remote DLUs, maximum 4 PDCs of 2 Mbps (32 TSs) are used per DLU, two towards each LTG. Hence total 124 channels are available between a DLU and the two LTGs, out of which 120 channels are used for user
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PDC3 without CCSPDC2 with CCS
PDC1 without CCS
PDC0 with CCS
Subscriber lines and PBX lines for small and med- ium-sized PBXs
Remote application
Local application
4Mbps
SNLTG
LTG
CP
4 MbpsDLU
DLU
Subscriber lines and PBX lines for small and medium-sized PBXs
CCITT standard interface G.703Remote application :
in same directory number area,in another directory number area,as extension to conventional exchange.
Applications and connection of Digital Line Unit
EWSD System Description
information (speech or data) and signaling information is carried in TS16 of PDC0 and PDC2. In case of a local DLU interface, TS32 carries the signaling information.
Within the DLU, the analog subscribers are terminated on SLMA (Sub-scriber Line Module Analog) cards (module). Similarly Digital (ISDN) subscribers are terminated on the SLMD modules. Each module can support 16 subscribers,
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EWSD System Description
hence has 16 SLCA/SLCDs (Subscribers Line Circuit Analog/Digital) and one processor SLMCP.
One DLU can carry traffic of 100 Erlangs. A standard rack of DLU (local ) can accommodate two DLUs of 952 subscribers each.
In case the link between a remote DLU and the main exchange is broken, the subscribers connected to the remote DLU can still dial each other but metering will not be possible in this case. For emergency service DLU-controller (DLUC) always contain up-to-date subscribers data. Stand Alone Service Controller card (SASCE) is provided in each R-DLU for switching calls in such cases ( call setup and release for analog and ISDN subscribers and enables DTMF dialling for push-button subscribers). This card is also used for interconnecting a number of remotely situated DLUs (maximum 6), in a cluster, called a Remote Control Unit (RCU), so that subscribers connected to these remote DLUs can also talk to each other in case the link of more than one DLU to the main exchange is broken.
All DLUs are provided with a Test Unit (TU) for performing tests and measurements on SLCAs, subscribers lines and telephones. An ALEX (ALarm EXternals) module is used for forwarding external alarms, i.e., fire, temperature, etc. to System Control Panel (SYP). Numbers of SLMAs are accordingly reduced to accommodate these modules. The main components of a DLU are:
SLMAs and / or SLMDs
Two Digital Interface Units for DLU (DIUD) for connections of the PDCs.
Two DLU Controls (DLUC)
Two 4 Mbps networks for the transmission of user information between SLMs and the DIUDs.
Two control network for the transmission of control information between SLMs and DLUCs.
Test Unit (TU), External Alarm module (ALEX) Alarm modules.
The latest type of DLU is DLUG which can accommodates upto 1984 analogue subscribers with 32 ports per SLMA but the SLMD still accommodates 16 subscribers. It can be connected to four LTGs with 16 PDCs with a provision of one signalling channel (CCS) per LTG. It can handle up to 390 Erlangs of traffic.
3.2 Line/Trunk Groups
The line/trunk groups (LTG) forms the interface between the digital environment of an EWSD exchange and the switching network (SN). MaximumMaximum traffic handling capacity per LTG is 100 Erltraffic handling capacity per LTG is 100 Erlang. The LTGs are connected in any of the following ways :
(i) Via 2/4 Mb/s PDCs with remote/local DLUs to which subscribers are connected
(ii) Via 2 Mbps digital access lines to other digital exchanges in the network ( MF( MF R2 Trunks, CCS#7 Trunks)R2 Trunks, CCS#7 Trunks)
(iii) Via Primary rate Access lines to ISDN PBXs (ISDN subscribers with PA)
(iv) V5.2 Trunks, Announcements Trunks, OCANEQ, X.25 Links for PSPDN, IP (iv) V5.2 Trunks, Announcements Trunks, OCANEQ, X.25 Links for PSPDN, IP (SSP)(SSP)
Functions
The primary functions of the LTG are as follows:
(i) Call processing functions, i.e., receiving and analyzing line and register signals, injecting audible tones, switching user channels from and to the switching network, etc.
(ii) Safeguarding functions, i.e., detecting errors in the LTG and on transmission paths within the LTG, analyzing the extent of errors and initiating counter-measures such as disabling channels or lines, etc.
(iii) Operation and maintenance functions, i.e., acquiring traffic data, carrying out quality-of-service measurements, etc.
The LTGs can work with all standard signaling systems (e.g. CCITT No. 5, R2, No.7). Echo suppressers like DEC120 can be incorporated in the LTGs for the connection of long-haul circuits (e.g., via satellite).
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EWSD System Description
Although the subscriber lines and trunks employ different signaling systems, the LTGs present signaling-independent interface to the switching network. This facilitates the following:
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Frame TYPEFrame TYPEFunctional TYPEFunctional TYPE
DIFFERENT FUNCTIONAL TYPES IN LTGDIFFERENT FUNCTIONAL TYPES IN LTG
LTGNLTGN
LTGLTG
B Function (For DLUs[L&R], PRI,V5.2,OCANEQ,COU)
C Function (For Trunks on CAS & CCS and CCS#7 signalling channels)
B Type (for special functions like COUC, PHMA ( V5.2), ATE:N, OCE:N)
A Type (For DLUs[L&R], PRI, Trunks)
In case of LTGP, A type frame is used for all type of functions In case of LTGP, A type frame is used for all type of functions except for user interactive LTG where B type frame is usedexcept for user interactive LTG where B type frame is used
EWSD System Description
- flexible introduction of additional or modified signaling procedures,- a signaling-independent software system in the CP for all applications.
The bit rate on all highways linking the line/trunk groups and the switching network is 8192 kbps ( 8 Mbps ). Each 8 Mbps highway contains 128 channels at 64kbps each. Each LTG is connected to both planes of the duplicated switching network.
The functional units of the line/trunk group are:
Line / Trunk Unit (LTU) is a logical unit that comprises a number of different functional units, i.e.
- Digital Interface unit ( DIU30 ) for connection of 2 Mbps digital trunks and either DLU or PA. One LTG can comprise four DIU30.
- Code Receivers (CR) are Multi-frequency code receivers for trunks or DTMF subscribers.
- Conference Unit, module B or module C (COUB or COUC) for conference calls. This is installed in special function LTGMs or LTGNs.
- Automatic Test Equipment for Trunks (ATE:N) checks trunks and Tone Generators (TOG) during routine tests. This is installed in special function LTGMs or LTGNs.
Signaling Unit (SU) comprises Tone Generator (TOG) for audible tones, Code Receivers (CR) for MFC signaling and push-button dialing and Receiver Module for Continuity Check (RM:CTC), etc.
Group Switch (GS) which functions as non-blocking time stage switch ( 512 TS) controlled by the GP.
Link Interface Unit (LIU) connects LTG to SN via two parallel 8 Mbps SDCs.
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EWSD System Description
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(8Mbps)
Address signals
SIHO
SIHI
SPHO
SPHI
LTU
DIU30
LTU
COUB
LTU
CR
LTU
ATE:T
CR TOG CTC
SU
SN0
SN1
to/from SN (8Mbps)
GSLIU
or
or
or
GP (PU, MU, SMX and GCG) SILC
Internal Structure of LTG
DIU:LDIB
COUC
PHMA
OCANEQ
EWSD System Description
Group Processor (GP) controls the functional units of the LTG. The received signals from LTU, SU, GS and LIU are processed with the help of GP software.
In LTGG, GS and LIU have been combined into GSL module. One LTG rack can accommodate 40 PCMs in five LTGG frames, each containing two LTGGs.
LTGM was the next standard type of LTG. Only three modules are necessary for a complete LTGM namely DIU120A or DIU:LDIM, GPL and GSM. Upto 30 LTGM can be installed in one rack with each frame containing 5 LTGM.
LTGN was introduced next to LTGM. Only one module (GPN) makes up a complete LTGN for the basic tasks. Upto 16 LTGN can be installed in frame F:LTGN(A) and a rack can contain 64 LTGN. However, if module like COUC, PHMA for V5.2, ATE:N, DEC120 or OCE:N is to be accommodated alongwith GPN to implement a special function, only 8 LTGN can be accommodated in F: LTGN(B).
LTGP is the latest release of LTG. One GPP module accommodates four LTG with a provision of one additional module like PHMA, DEC120 or OCE:N etc for each GPP to implement a special function. Up to 32 LTG can be installed in one frame F:LTGP(A) and a rack can accommodate 192 LTG using six frames. However, if one of the LTG is to work as a user Interactive LTG requiring module OCE:N and one or two modules VPU:N, the frame required will be F:LTGP(B) which can accommodate 28 LTG in one frame.
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EWSD System Description
3.3 Switching Network
Different peripheral units of EWSD, i.e., LTGs, CCNC, MB are connected to the Switching Network (SN) via 8192 kbps highways called SDCs (Secondary
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LTG 1
LTG n
CCNC
CP
SPACE STAGE GROUP
TIME STAGE GROUP
SGC
SGC
Switching Network
SDC:LTG
SDC:LTG
SDC:CCNC
SDC:TSG
SDC:SGC
SDC:SGC
SN
MB
SDC:SSG
SDC:SSG
EWSD System Description
Digital Carriers), which have 128 channels each. The SN consists of several duplicated Time Stage Groups (TSG) and Space Stage Groups (SSG) housed in separate racks. Connection paths through the TSGs and SSGs are switched by the Switch Group Controls (SGC) provided in each TSG and SSG, in accordance with the switching information from the coordination processor (CP). The SGCs also independently generate the setting data and set the message channels for exchange of data between the distributed controls.
The switching network is always duplicated (planes 0 and 1). Each connection is switched simultaneously through both planes, so that a standby connection is always immediately available in the event of a failure.
Each TSG can accommodate 63 SDCs from LTGs and one SDC to MB. One SDC is extended from SGC of each TSG and SSG towards MB. Thus one TSG can handle upto 63 LTGs. The switching network can be expanded in small stages by adding plug-in modules and cables and if necessary by assigning extra racks.
Optimized switching network configurations are available in a range of sizes. The smallest duplicated SN:63 LTG configuration which can handle 30,000 subscriber lines or 7,500 trunks when fully equipped is installed in a single rack and can handle 3150 erlangs traffic. In its maximum configuration, the EWSD switching network has 8 TSGs and 4 SSGs (in 12 Racks) to connect 504 LTGs and has a traffic - handling capacity of 25,200 erlangs. SNs for 126 LTGs and 252 LTGs are also available which can handle 6300 and 12600 erlangs traffic respectively.
SN(B) has only 5 types of modules and each TSG and SSG is accommodated in only two shelves of the respective racks. Remaining four shelves accommodate LTGs.
Main Functions:*Speech Path Switching
*Message Path Switching
*CCS#7 signaling channels connection (NUC)
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Maximum configuration of CP113C
CAP0 IOC1IOC0BAPSBAPMCAP5
IOP
IOP IOP
IOP
CMY1
CMY0
IOC3IOC2
IOP IOP
IOP IOPBasic configuration of CP 113C,
11 . .
0
11 . .
0
B:IOC B:IOC
AMP0 AMP1
Hardware Structure of CP 113 C
EWSD System Description
3.4 Coordination Area
3.4.1 Coordination Processor
The coordination processor (CP) handles the data base as well as configuration and coordination functions, e.g.:
- Storage and administration of all programs, exchange and subscriber data,
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BCMY0
BCMY1
EWSD System Description
- Processing of received information for routing, path selection, zoning, charges,
- Communication with operation and maintenance centres,
- Supervision of all subsystems, receipt of error messages, analysis of supervisory result messages, alarm treatment, error messages, alarm treatment, error detection, error location and error neutralization and configuration functions.
- Handling of the man-machine interface.
The CP113C is multiprocessor and can be expanded in stages. In the CP113C, two or more identical processors operate in parallel with load sharing. The rated load of n processors is distributed among n+1 processors. This means that if one processor fails, operation can continue without restriction (redundancy mode with n+1 processors).
The Basic functional units of CP 113C are as follows:
- Base Processor (BAP) for operation & maintenance and call processing,
- Common Memory (CMY)- 64 to 1024 MB in 4 memory banks consisting of 4 Mb DRAM chips.
- Input / Output Controller (IOC) - 2 to 4 IOCs coordinate and supervise accessing of CMY by IOPs.
- ATM Bridge Processor (AMP) – If a SSNC (EWSD powernode) is connected, the AMP is used (usually instead of the second IOC pair). It represents the interface between the ATM equipment in the SSNC and the CP. Its task is to convert the ATM oriented data streams from SSNC to the internal EWSD format.
- Input/output processors (IOP) - Various types of IOPs are used to connect the CP113C to the other subsystems and functional units of the exchange as well as to the external mass storage devices (EM i.e., MDD, MTD, MOD), the two O&M terminals (OMT/ BCT), to OMC via data lines etc. Maximum 12 IOPs can be connected to one IOC. The figure is shown on next page.
The other functional units of CP 113C are call processors (CAPs) which deal only with call processing functions. Hardware wise they are similar to BAPs
3.4.2 Other units assigned to CP are:
Message Buffer (MB) for coordinating internal message traffic between the CP, the SN, the LTGs and the CCNC in an exchange.
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EWSD System Description
Central Clock Generator (CCG) for the synchronization of the exchange and,
where necessary, the network. The CCG is extremely accurate (10-9). It can,
however, be synchronized even more accurately by an external master clock (10-
11).
System Panel Display (SYPD) to display system internal alarms and the CP load. It thus provides a continuous overview of the state of the system. The SYP also displays external alarms such as fire and air-conditioning system failure for example. It is installed in the Equipment Room or in the Exploitation Room.
Operation and Maintenance Terminals/ Basic Craft Terminal for Input/output. Two OMTs/ BCTs are provided for O&M functions.
External memory (EM), for
- Programs and data that do not always have to be resident in the CP,- An image of all resident programs and data for automatic recovery,- Call charge and traffic measurement data.
To ensure that these programs and data are safeguarded under all circumstances, the EM is duplicated. It consists of two magnetic disk devices (MDD). The EM also has a magneto optical disk ( MOD) and/or magnetic tape device (MTD), for input and output.
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EWSD System Description
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Alarm function : monitors fans of CP racks
BIOC0
CCG
MBG
CCNP
IOP:MB
IOP:MB
IOP:MB
IOP:MB
IOP:MB
IOP:TA
IOP:TA
IOP:UN1
Number depends on SN size.
IOP:MB
MDD
MOD
MTD
OMT/BCT/
NetM boot
Data lines
MDD
MOD
MTD
OMT/BCT/
NetM bootData lines
BIOC1
IOP:UN1
IOP: SCDP
LCUB LAUB
LCUB LCUB
(IOP:LAU) ((LAU)
(IOP:LAU) ((LAU)
X.25 links to e.g. OMC, CT or billing center normally with EWSD Classic
IOP:MB
IOP:MB
SYPC
IOC1IOC0
BCMY0
BCMY1
Structure of the CP113C input/output system with 2 IOCs
Normally with EWSDClassic
EWSD System Description
3.5 Units for Message transfer part (MTP) of CCS#7
The CCITT- standardized signaling system No.7 (CCS#7) is one of the systems that is used for interexchange signaling in EWSD. To promote flexibility in the use of this system a distinction is made between a message transfer part (MTP) and the user parts (UP). The user parts vary according to the specific application (e.g. TUP: telephone user part, ISDN-UP: ISDN user part, MUP: mobile user part). The common MTP functions in an EWSD exchange are handled by the common channel signaling network control (CCNC) or Signaling System Network Control (SSNC). The UP is incorporated in the software of the relevant LTG.
(a) Common Channel Signaling Network Control (CCNC)A maximum of 254 common signaling channels can be connected to the
CCNC via either digital or analog links. The digital links are extended from the LTGs over both planes of the duplicated switching network and multiplexers to the CCNC. The CCNC is connected to the switching network via two 8 Mbps highways (SDC: CCNC). Between the CCNC and each switching network plane, 254 channels for each direction of transmission are available (254 channel pairs). The channels carry signaling data via both switching network planes to and from the LTGs at a speed of 64 kbps. Analog signaling links are linked to the CCNC via modems.
For reasons of reliability, the CCNC has a duplicated processor (CCNP) which is connected to the CP by means of similarly duplicated bus system. The CCNC consists of :
- Upto 32 signaling link terminal (SILT) groups, each with 8 signaling links and
- One duplicated common channel signaling network processor (CCNP).
The functions of the CCNC depend on its position in a signaling link. In the originating or destination exchange in associated signaling, it operates as signaling end point (SEP) and in transit exchange in quasi-associated signaling, it operates as a signaling transfer point (STP).
The CCNC, equipped in one rack can handle upto 48 signaling links. Equipments handling upto 96 signaling links can be equipped in additional racks.
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CCS via digital data links
CCS via analog data links
0 310 31
0 70 7
SILT group 31SILT group 0
CCNP 0 CCNP 1
CP bus system
Common Channel Signalling Network Control
MultiplexerModem
EWSD System Description
(b) Signaling System Network Control (SSNC)
General Characteristics of the SSNC:
In the EWSD powernode the SSNC takes over the control of the SS7 network (instead of CCNC as was used in EWSD Classic). Here SSNC can be used as signaling end point (SEP) or signaling transfer point (STP) as was also done by CCNC.
Additionally the SSNC can also take over the tasks of a SCCP Relay Point SRP (Global Title Translation GTT for MTP users at non-user channel related SS7 signaling) and can function as a Local Number Portability Database Server.
In Contrast to the CCNC, the SSNC is equipped with its own O&M interface to the Netmanager NetM (Ethernet IP interface with Q3 protocol) and with back-up memories (magnetic disk / magneto-optic disk). Therefore with regard to the OAM, it is independent of the CP. Thus it is possible to also use the SSNC outside of EWSD as a stand-alone Signaling Transfer Point STP. Figures on the next page show how the CCNC or SSNC are connected in EWSD Classic and Powernode configurations respectively.
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EWSD System Description
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Trunks andSS7 Links
LTG
LTGSNB
CCNC
MB B
IOP:MB IOP:MBCP
EWSD Classic Configuration
PCM30
8 Mb/s
4 Mb/s OMT/CTOMT/CT
LTG
LTGSNB
SSNC
MB D
AMPC IOP:MB
CP
EWSD Powernode Configuration
Trunks andSS7 Links PCM30/24
270 Mb/s
207 Mb/s
High SpeedSS7 Links
NetM
EWSD System Description
Comparison Table for various traffic types between CCNC and SSNC:
Traffic Type CCNC SSNC (Ver. 16) SSNC Single Shelf Configuration (Ver.16)
The SS7 Signaling channels can be connected to the SSNC in three ways: Direct connection of 2 Mbps PCM transmission routes (E1) with 32 x 64Kbps slots
(Synchronous Transfer Mode STM) where the time slot 1-31 is used exclusively for 64Kbps SS7 Signaling channels(usually used when using the SSNC as stand-alone signaling transfer point (STP)
Direct connection of 2Mbps PCM transmission route (E1) with a 2 Mbps high speed SS7 signaling channel (Asynchronous Transfer Mode ATM)(usually used when using the SSNC as stand-alone Signaling Transfer Point STP)
Indirect connection (via EWSD) of 64 Kbps SS7 signaling channels located in 2Mbps PCM transmission routes which simultaneously transport user channels.
(not with stand-alone STP)
The connection of such an SS7 signaling channel occurs as a nailed-up connection (NUC) from the LTG to which the PCM route transporting the channel is connected via the EWSD switching network to the SSNC. Because the SSNC, however, has no direct interface to the SN, this NUC runs via the switching network only to another LTG (inward LTG). This collects several SS7 NUC’s from different LTG’s and the bundled routes in a 2 Mbps cable with maximum 31 signaling channels to the SSNC.
b) Interface to the CP :The connection to the CP is used to monitor and communicate with the CP for SS7 messages relevant for the CP and for Internal OAM- messages as e.g. Load Control,
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EWSD System Description
checking of data consistency. It is connected using 207 Mbps optical fiber cable to the AMP in the CP.
c) Interface to the MB D The SSNC has up to 10 ATM200 interfaces to the MBDA in the MB D. The EWSD internal exchange of the SS7 ISUP messages between the user LTGs and the SS7 MTP functions in the SSNC runs via these interfaces.
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Output LTG
ISUP LTG
Inward LTG
AMP MB- D (MBDA)
CP
SNSignaling link
Affecting speech channel
SSNC
OAM
Level 2 & 3(MTP)
ATM- bridges (optical)
Net M
31 SS7- Linkswith 64 Kbit/sor 1 HS- Link with 2 Mbit/S
Direct connected E1 exclusively used for SS7 links
SSNC Interfaces
EWSD System Description
SSNC Functional Units/ Frames:Three types of module frames are used for the SSNC. The SSNC racks are manufactured in the ICN construction, i.e. they are somewhat deeper and wider than EWSD structure.
a) ATM Switching Network ASN (2 module frames for ASN 0 and 1) The ATM switching network (ASN) is a switch matrix which
Switches the communication- streams of the individual SSNC functional units with MB D and CP
Switches the communication-streams between the individual SSNC functional units
b) SSNC basic frames SCB Only this frame is required for single shelf configuration of SSNC. The SCB contains the following (internally duplicated) functional units of the SSNC:
Line Interface Card (LIC):The duplicated Line Interface Card LIC forms the physical interface between the SSNC units and the SS7 network.Up to 8 PCM 2Mbps lines can be connected to an LIC module. These PCM routes can come either directly from the transmission network or from different inward LTG’s. Therefore an LIC can provide the interfaces for maximum 248 x 64Kbps signaling channels.
Main Processor MP:The Main Processor (MP) are the central components of the SSNC. Each MP is duplicated (MPU0 and MPU1). The different MP’s fulfil different tasks:
MP: OAM (MP for Operation , Administration and Maintenance): It contains interfaces to connect Netmanagers NetM (Ethernet), the hard disks (SCSI bus for MDD and MOD) and the connection units for alarm lines ALIB (Alarm Line Interface Base).MP:SLT (MP for Signaling Link Termination):Each MP:SLT carries out the MTP tasks of an SS7 network control for maximum 127 signaling channels (depending on signaling traffic) when dealing with SS7 messages (discrimination, distribution, routing and back-up).The total number of the MP:SLT in the SSNC depends on the signaling requirements of the network node (maximum 47 MP:SLT can be provided).MP:SM (MP for Signaling Manager):It serves to permanently update the SSNC database. This also guarantees that each MP:SLT always has an up-to-date picture of the signaling database.MP:STATS (MP for statistics)The MP:STAT is used to administers the different SS7 statistics data which are collected in the individual MP:SLT.
ALTTC/SW-II 23/26 F11-Sys/01.10.2005
EWSD System Description
In case of SSNC single shelf configuration only two (duplicated) MPs are used. One is supplied with a mixed load type MP:OAM/SM/STATS while the other one performs the MTP tasks (MP:SLT)
ATM Multiplexer Type-E (AMXE):
The AMXE serves as a concentrator towards ASN and provides 32 x 207 Mbps ATM interfaces to connect the internal SSNC units LIC and MP and the optical cables to the AMP of the CP and MBDA of the MB
c) Extension frame SCE (maximum 7 for 1500 signaling channels)The SCE contains a duplicated AMXE and serves to include other MPs and LICs .
Annexure
ALTTC/SW-II 24/26 F11-Sys/01.10.2005
LTG
LTG
LTG
LTGDLU
LIC
LIC
MP:SLT
MP:SLT
MP:STATS
MP:SM
MP:OAM
AM
XE
AS
N
SSNC
Trunks and SS7 Links (64 kbps)
SS7 Links(64Kbps)
High SpeedLinks (2 Mbps)
MB DMB
DA
AMPC IOP:MB
CP113C
X. 25
Ethernet
MOD
MDD
NetM
EWSD System Description
System Data
Call-handling capacity No. of Subscriber lines max. 250 000No. of Trunks max. 60 000Switchable traffic max. 25 200 E.
Supply voltage -48 V nominal direct voltage
Clock accuracy Maximum relative frequency deviation :
plesiochoronous 10-9; synchronous 10-11
Signaling systems All conventional signaling systems,e.g. CCITT R2, No.5, No.7
Analog subscriber line Various loop and shunt resistance possible.and trunk accesses Push-button dialing, Multi-freq. signaling to
CCITT Recommendation Q.23Rotary dialing: 5 to 22 pulse/s
Traffic routing Per destination one primary route and max. 15 alternate routes.Sequential or random selection of idle trunk of a trunk groupNumber of trunk groups per exchange:
