Axe Access 910 System Description
-
Upload
nguyen-thua-cong -
Category
Documents
-
view
65 -
download
10
Transcript of Axe Access 910 System Description
AXE Access 910Introduction
1999-10-01
Rev PA4
3
Table of Contents
1. Introduction 51.1 Purpose. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51.2 Knowledge of the reader. . . . . . . . . . . . . . . . . . . . . . . . . . 51.3 This is a training document . . . . . . . . . . . . . . . . . . . . . . . . 5
2. System Overview 72.1 Chapter Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72.2 Some General Points About Access Nodes . . . . . . . . . . . 72.3 Main Hardware Structure . . . . . . . . . . . . . . . . . . . . . . . . . 92.4 Access Units . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122.5 AUS, Access Unit Switch . . . . . . . . . . . . . . . . . . . . . . . . 132.6 AUS Network . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152.7 Test Unit (TAU) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 172.8 Equipment in the Local Exchange . . . . . . . . . . . . . . . . . 172.9 Improved Characteristics . . . . . . . . . . . . . . . . . . . . . . . . 19
3. Hardware Structure, BYB 501 233.1 Chapter Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . 233.2 BYB 501, a New Building Practice . . . . . . . . . . . . . . . . . 233.3 Subracks in AXE Access 910 . . . . . . . . . . . . . . . . . . . . . 303.4 Cabling Inside Access 910 . . . . . . . . . . . . . . . . . . . . . . . 333.5 Printed Circuit Boards . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
4. Software Structure 434.1 Chapter Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . 434.2 Set of Parts, CRT level . . . . . . . . . . . . . . . . . . . . . . . . . . 434.3 Access Unit V5 Application, AUV5 . . . . . . . . . . . . . . . . . 444.4 Multiple Access Unit Switch, MAUS . . . . . . . . . . . . . . . . 494.5 Multiple Access, Operation, Administration and
Maintenance, MAOAM . . . . . . . . . . . . . . . . . . . . . . . . . . 50
AXE Access 910
4
5. New Functions and Features 535.1 Chapter Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . 535.2 Hardware-Related Functions . . . . . . . . . . . . . . . . . . . . . 535.3 Equipment Protection Switching . . . . . . . . . . . . . . . . . . . 555.4 HDSL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 575.5 ADSL. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 585.6 SDH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 625.7 Operation and Maintenance Functions . . . . . . . . . . . . . . 645.8 New EMRP platform . . . . . . . . . . . . . . . . . . . . . . . . . . . . 665.9 V5 Related Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . 695.10 Stand Alone Function, SAF. . . . . . . . . . . . . . . . . . . . . . . 715.11 Subscriber Line Maintenance Functions. . . . . . . . . . . . . 715.12 Modified and Removed Functions . . . . . . . . . . . . . . . . . 71
6. Operation 736.1 Chapter Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . 736.2 Concepts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 736.3 Definition of Equipment in the Local Exchange . . . . . . . 746.4 Definition of a MACCG . . . . . . . . . . . . . . . . . . . . . . . . . . 77
7. Maintenance 857.1 Chapter Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . 857.2 Maintenance Principles. . . . . . . . . . . . . . . . . . . . . . . . . . 857.3 Equipment Protection Switching . . . . . . . . . . . . . . . . . . . 87
8. Future Functions 898.1 Chapter Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . 898.2 Compatible Hardware . . . . . . . . . . . . . . . . . . . . . . . . . . . 898.3 Remotely Controlled MDF. . . . . . . . . . . . . . . . . . . . . . . . 908.4 Integration of IP and ATM . . . . . . . . . . . . . . . . . . . . . . . . 91
5
1. Introduction
1.1 PurposeThe main purpose of this book is to describe the new functions and products in AXE Access 910. The book gives an overview of the AXE Access 910 and describes some of the most important functions. Main focus of the contents is on the hardware structure but information is provided describing software as well as operation and maintenance.
This book does not provide any information about the compatibility between AXE Access 910 and different versions of APT or APZ. This will be described in separate documents when the system is released.
1.2 Knowledge of the readerTo fully understand the subject matter in this book, the reader must have some knowledge of AXE as well as the previous version of the subscriber switching subsystem (SSS5).
1.3 This is a training documentPlease note that this is a training document and not a formal description of the system. Therefore, it may include simplifications of the system. Implementation details may also change while this book is being written. For accurate information about the system, please consult the official system descriptions.
AXE Access 910
6
7
2. System Overview
2.1 Chapter IntroductionThis chapter will give you an overview of AXE Access 910. Basic concepts and the main structure of the system will be explained as well as some points about access nodes in general. By reading this chapter, you will get a general picture of the different parts of AXE Access 910 and its functions.
2.2 AXE and Ericsson Access 910Ericsson develops two variants of the access system Access 910. One variant, referred to as AXE Access 910, can only be connected to AXE exchanges. One can say that AXE Access 910 replaces the existing SSS/RSS as some proprietary interfaces are kept. The other variant, the Ericsson Access 910, can be connected to any suppliers local exchange as long as it supports the standard interface V5.2. More about the V5 interface later on in the book.
At the same time, both indoor and outdoor versions of these two variants are developed in different sizes. Main focus of this document is to describe the AXE Access 910 in indoor version. Figure 2.1 shows the variants developed and how they relate to each other.
After completing this chapter, you will be able to:• Describe the general system structure of AXE Access 910• Describe how the different parts of the system co-operate• State the units used in the system and understand their basic
functions.
Chapter Objectives
AXE Access 910
8
Figure 2.1Relationship between AXE and Ericsson Access 910
From a hardware point-of-view, the difference between AXE and Ericsson Access 910 is one single board. The differences between the in-door and out-door version is the mechanics surrounding the subracks.
2.3 Some General Points About Access NodesToday, the development of access nodes takes two paths: one which keeps the access tied to the local exchange and one which tries to loosen-up this connection. In the latter case, a standardised interface is used: ETSI V5. In the first case, proprietary interfaces are still in use.
For AXE Access 910, a combination of V5 and proprietary interfaces are used. This means that the access node should be seen as a part of the AXE local exchange, just as with the old SSS5. Figure 2.2 illustrates the main idea.
AXE Access 910 Ericsson Access 910
In-door
Out-door
AXE management Separate managementsystem (UNIX based)
xDSL
MiniMidiMaxi
MiniMidiMaxi
This document
xDSL management
System Overview
9
Figure 2.2AXE Access 910 can be used as a remote access node for an AXE local exchange
The access nodes will in most cases be remote from the local exchange. The main reason for this is economy: putting the access nodes close to the subscribers results in a less costly access network. For broadband services, like ADSL (Asymmetrical Digital Subscriber Line), it is also important to have short subscriber lines as the bandwidth depends on the quality and the length of the subscriber’s copper cable. The “transport network” indicated in Figure 2.2 will in the future most likely be based upon optical fibres in a ring structure. For that reason, the access nodes are equipped with SDH interfaces which can connect them to the optical fibre (add/drop multiplexers). This will create a high-capacity access transport network that is very flexible and fully prepared for broadband access.
2.3.1 New Services in the Near FutureA “hot issue” within telecom is how operators should handle Internet access, broadband services and other new functions affecting the access. The ideal solution is to have common hardware for all types of access. It is difficult for an operator to anticipate the new services coming soon. How many subscribers in a given area will be interested in the new services? When will they be interested? The absence of precise answers to such questions makes it difficult to plan the network. It is best to have one common access node for a large number of services delivered through the traditional copper wire. You will find more information about future functions and features in chapter 8. Please study Figure 2.3.
AXE Access 910
AXE Access 910
AXE Access 910
Transportnetwork
Core part of AXE
AXE Access 910
10
Figure 2.3Future services delivered by AXE Access 910
2.3.2 V5 Interface Gives FlexibilityAn important issue for network operators is the use of an open protocol between the local exchange and the access nodes. Many operators wish to have local exchanges and access nodes which come from different suppliers. These operators can buy the best local exchange and connect that to the best access node, regardless of manufacturer. This is already a possibility in mobile systems (e.g. GSM) where base stations and exchanges can be supplied by different manufacturers.
ETSI, European Telecommunications Standardisation Institute, has developed a standard interface which can be used between the local exchange and the access node: the V5 interface. There are two different variants of this interface:
• V5.1 is used for multiplexers connected by a standard 32-channel 2 Mbit/s line to the local exchange.
• V5.2 is used for concentrators having the ability to concentrate the traffic towards the local exchange.
Figure 2.4 illustrates the main principle.
Figure 2.4The two types of V5 interfaces
AXE
?
Access 910
POTS
ISDN
ADSL
HDSL
VDSL
PABX
Multiplexer
Concentrator
Local Exchange2 Mbit/s
V5.1
V5.21
~ 1000
1
30
2 Mbit/s
System Overview
11
In most applications, the concentrator connects between 500 and 2000 subscribers, and concentrates the traffic to a few 2 Mbit/s lines. The multiplexer cannot concentrate the traffic, so each subscriber is permanently connected to the same time slot on the 2 Mbit/s link.
2.4 Main Hardware Structure
2.4.1 Access Unit and Access Unit SwitchThe hardware structure of AXE Access 910 is much more simple than the SSS5 structure. There are less board types, and more functions are put on each printed board assembly (PBA). The mechanics, which will be explained in chapter 3, is based upon the state-of-the-art building practice BYB 501. The boards in BYB 501 are larger than in the existing SSS based upon BYB 202.
We will now leave the hardware for a while and focus on the structure of the system. Figure 2.5 shows the hardware structure.
Figure 2.5The main hardware structure of AXE Access 910
The Access Units (AU) are line boards, Line Interface Boards in the context of SSS5. The AUs differ in size and capacity. Different access units are used to deliver different types of services (e.g. POTS, ISDN-BA, HDSL or ADSL). For test of both the AUs and the subscriber lines, there is a test unit referred to as TAU. TAU stands for Test, Maintenance and
AU
AU
TAURPG
AU
AU
TAU
ETC
CP-A CP-B
ETC
ETC
ETC
RPG
RPRP
AU
2 Mbit/s
AUS
AU
TAURPG
AU
AUS
AU
TAU
ETC
CP-A CP-B
ETC
ETC
ETC
RPG
GS
RPRPRPB
ISDN-PRA
AU
SDH (155 Mbit/s)
ET
AXE Access 910 AXE core part
ISDN-BA
ADSL
PSTN
AXE Access 910
12
Administration Unit. The TAU corresponds to the SLCT in the old SSS5 structure. The number of subscribers per TAU is determined by the intensity of subscriber line test.
The Access Unit Switch (AUS) is the common parts assembled in one single board. The AUS contains a time switch, keyset code receivers, tone senders, and a processor. Several AUs are connected to one AUS by means of standard 2 Mbit/s lines. The AUS concentrates the traffic to a few 2 Mbit/s lines towards the local exchange.
In the local exchange, the 2 Mbit/s lines are connected via ETCs, Exchange Terminal Circuits, to the group switch. For communicating with the AXE Access 910, a number of RPGs are needed. RPG stands for regional processor with group switch interface.
2.4.2 The AUS NetworkAll the AUSs in one access node are connected to each other. Please study Figure 2.6.
Figure 2.6AUS in one access node, and the AUS network
Figure 2.6 shows a number of AUSs in one access node. From each AUS, there are a number of 2 Mbit/s lines going to the local exchange. The dimensioning of this is explained in chapter 2.11.6 on page 22 but the number is in the range of 1-5. The AUS network, which is further explained in chapter 2.8 on page 16, is used for EMRP communication and for the overflow traffic. One can say that the AUS network replaces both the EMRP bus and the Time Switch Bus in SSS5. The AUS network is also based on standard 2 Mbit/s links.
2.4.3 V5 interfaceIt was mentioned earlier that the V5 interface is used in AXE Access 910. The V5 variant for multiplexers, the V5.1 interface, is used. How, then, is
AUAUS
AU
AUAUS
AU
AUAUS
AU
To Local Exchange
AUS Network
System Overview
13
that possible since the whole AXE Access 910 is a concentrator and not a multiplexer? The answer is that each AU, Access Unit, is regarded as a multiplexer (and it is...) and is controlled via the V5.1 protocol. The AU has a powerful processor which runs the V5.1 software. The other end of the protocol is in the local exchange where an RPG is used for the V5.1 software. Note that the V5.1 interface is only used for AU of type PSTN and ISDN-BA (not for broadband access). Please study Figure 2.7.
Figure 2.7The V5.1 protocol used in AXE Access 910
2.5 Access UnitsThe general term “access unit” is used to denote all types of accesses that can be used in AXE Access 910. Different access units will be developed for different types of narrowband and broadband applications. Today, there are two main variants for narrowband:
• Two different access unit for PSTN access
− LIC30 based upon standard SLIC circuits with or without 12/16 kHz private meter pulse sending
− ALB30 with high functionality requested on some markets only
• An access unit for ISDN-BA access (2B+D).
As broadband is included in AXE Access 910, there will be special line boards for this type of access as well:
• An access unit for HDSL, high-speed digital subscriber line• An access unit for ADSL, asymmetrical digital subscriber line
ISDN PRA, primary rate access, can also be connected to the AXE Access 910 system. However, it is connected directly to the AUS without using any specific access unit.
AU
AU
AU
AUAUS
ETC
GroupSwitch
RPG
CP-A CP-B
T. 16
T. 16
V5.1
AXE core partAXE Access 910
AXE Access 910
14
All existing narrowband access units have some common parts. Figure 2.8 shows a block diagram valid for all types of narrowband access units.
Figure 2.8Block diagram for an Access Unit, AU (narrowband)
2.6 Connection of ISDN-PRAEach AUS, Access Unit Switch, contains a large number of ET circuits for connection of 2 Mbit/s E1 links. Instead of connecting an AU board, the ET circuit can connect an ISDN PRA connection. The PRA connection is made via a standard E1 link of 2 Mbit/s. The functionality will be in accordance with the ETSI standard. Please study Figure 2.9.
Figure 2.9Connection of ISDN Primary Rate Access
2.7 AUS, Access Unit SwitchThe AUS is, as already mentioned, the central unit in the access node. The unit performs the switching functions and concentrates the traffic to the local exchange. Common telephony functions like digit reception of
-48V
LineInterface
NetworkTerminal
AU Control(processor)
Power
Speech
Data
V5.1
AUS2 Mbit/s
PABX
ET ET
ET
ET
ET
AU AUS
ISDN-PRA
DDF
ET ET
ET
ET
ET
MDF
2.048 Mbit/s
System Overview
15
DTMF signals and tone sending are also performed by the AUS. The unit performs the following functions:
• Synchronisation of the local time switch (slave to the group switch in the local exchange)
• Switching of speech samples in a 1K time switch• Attenuation of speech samples• Transmission of tones to subscribers (e.g. dial tone)• Reception of DTMF signals (digits from push-button telephones)• Connection of the 2 Mbit/s digital links (E1 links).
The unit also contains a new EMRP-T (Extension Module Regional Processor connected to the Time switch) and, in two of the AUSs in every access node, functions for an STR, Signalling Terminal Remote. Figure 2.10 shows the main parts of the AUS.
Figure 2.10The main parts of the AUS, Access Unit Switch
Here follows a short description of each unit shown in the figure:
• SwitchThe switch handles 1024 channels of 64 kbit/s each. The switch can also attenuate the speech samples.
• ClockOne AUS in the access node is master and all other clocks in the node follow the clock of the master. Another AUS has a clock which acts as stand-by master in case of failure. The timing information is distributed
ET
Clock
Switch andattenuation
DTMF,tones
HDLC
ET
ET
ET
ET
ET
ET
ET
pool
EMRP STR
ETKR TSW V24 STCON
“EMRPB”
“DEVCB”
To LocalExchange
AUS
To AU
To TAU
Network
Access Unit Switch
V.24
Sync. ring
EMRP-T
orPRA
AXE Access 910
16
via a separate, duplicated, bus in the backplane of the AUS subrack. The hardware is a VCXO, Voltage Controlled Crystal Oscillator, delivering 16,384 Mhz.
• ET, Exchange TerminalsThe ET circuits terminate the E1 links operating at 2 Mbit/s (2.048 Mbit/s). Channel 0 is used for synchronisation and the remaining 31 channels can be used for calls or signalling (e.g. V5.1 signalling). The links conform to ITU standard G.703, G.704, and G.706. The interface is a 120 ohms balanced interface. The standard AUS board has 28 ET circuits.
• HDLC poolThe HDLC circuit is a data communication circuit (high-level data link control) and it is integrated in the microprocessor. The hardware can handle 32 HDLC channels and they will be used for STC-STR communication, AUS interwork via the AUS network, and V5.1 concentration. In the case of standalone traffic, the V5.1 signalling links are terminated in the HDLC circuits.
• DTMF tonesThis hardware, that is used to receive DTMF tones, is based upon a DSP, digital signal processor. This hardware has the capacity to handle 32 devices (KRC devices). As well as receiving tones, it also generates them. New tones can be generated without changing the hardware.
• AUS control systemThe new powerful EMRP-T will replace the old EMRP, the device processors as well as the STR (in two AUSs per node). In the figure, dashed lines indicate that these latter functions are now handled by the same hardware. The software executed by the new EMRP has to be written in C or C++. Old PLEX-M programs are converted to C before being compiled.
• Serial interfaceThe AUS has two V.24/V.28 ports for connecting the local debugger and a portable terminal (PC).
2.8 AUS NetworkThe AUS network is a common name for two separate functions. One function, which replaces the EMRP bus in the old SSS5 structure, is for EMRP-T communication. The other function, which replaces the Time Switch Bus, TSB, in the old SSS5 structure, is for local connections and overflow traffic.
2.8.1 EMRP RingThe EMRP ring is the name for the function replacing the EMRP bus. It is used for EMRP-EMRP communication and uses standard 2 Mbit/s links. It is built as a ring because security and information can be sent in both directions on the ring. If one part of the ring becomes faulty, the ring can still handle signalling between all connected EMRPs. Figure 2.11 illustrates the principle, with 6 AUSs in the subrack.
System Overview
17
Figure 2.11The redundant EMRP ring
The 31 channels on the EMRP ring are not fully used for EMRP communications. The EMRP ring will probably need 4 time slots to have the same capacity as the EMRP bus in the old SSS5. Remaining channels can be used by the Mesh network (see next chapter).
2.8.2 Mesh NetworkThe Mesh network will replace the Time Switch Bus in the SSS5 structure and will consequently be used for calls. The Mesh network will also be implemented by standard 2 Mbit/s links and all AUSs will be connected to each other. That is why it is referred to as a Mesh network. Figure 2.12 shows some examples of configurations with 3 to 6 AUS in one subrack.
Figure 2.12The Mesh network with different numbers of AUSs
AUS
AUS
AUS
AUS
AUS
AUS
AUS
AUS
AUS
AUS
AUS
AUS
Faulty link
Example with fault:
AUS
AUSAUS
AUS AUS
AUS AUS
AUS
AUSAUS
AUS AUS AUS AUS
AUS
AUSAUS
AUS
3 AUS 4 AUS
5 AUS 6 AUS
AUS
AUSAUS
AUS AUS
AUS AUS
AUS
AUSAUS
AUS AUS AUS AUS
AUS
AUSAUS
AUS
AXE Access 910
18
The Mesh network is pre-cabled according to the customer’s wish of maximum number of AUSs. This means that the subrack is prepared for a maximum number of AUSs and that extensions are made easy and quickly without the need for additional cable work.
Please note that the spare AUS is not shown in the figure (there is always one spare AUS for reliability reasons).
2.9 Test Unit (TAU)TAU, Test, Maintenance and Administration Unit, is the unit in AXE Access 910 that replaces the SLCT, subscriber line and circuit tester, in the old structure of SSS5. The TAU is shared by a large number of subscribers - the exact number depends on how often it is necessary to perform line measurements. TAU has two connections to the Access Units:
• one analog test bus which galvanically connects the measurement equipment inside the TAU to the subscriber line and analogue side of the line circuit.
• one connection to the AUS which, via the time switch, connects the TAU to the digital side of the line circuit.
The TAU can measure the subscriber line as well as test the line circuit by means of simulated subscriber actions such as on and off hook.
The number of TAU needed for each access node depends on the total number of subscribers as well as the intensity of line tests. The test interval is set by the network operator and varies between different operators. Figure 2.13 shows where the TAU is located in the system.
Figure 2.13The TAU in the AXE Access 910
2.10 Equipment in the Local ExchangeThe local exchange contains all the main software functions for operation, maintenance and traffic control. Central software, stored and executed by the central processor, must communicate with the regional software in the
ET
ET
ET
ET
LICTest access
AU
TAU
Test Head
AUSSwitch
ET
ET
ET
LIC
ET
System Overview
19
access node. For this reason, reliable communication between the local exchange and the access node is vital.
One difference between the former SSS5 and the AXE Access 910 is that no centrally located version of the AXE Access 910 will be developed. All AXE Access 910 access nodes will be connected in the same way, regardless of location (via ETC in the local exchange). The reason for this is that it is estimated that 80% of all access nodes will be installed remotely. The hardware required to connect and signal to/from the AXE Access 910 can be divided into the following:
• Physical connection of the E1 digital linksThe connection is made by ordinary 2 Mbit/s ETCs in the local exchange. The hardware is the same as any standard ETC.
• Signalling with V5.1The V5.1 interface requires regional processors connected to the group switch. These regional processors are referred to as RPG, regional processor with group switch interface, developed for the AXE hardware BYB 501.
• Signalling to ISDN-PRA accessOne set of RPG is required for the signalling towards PRA access.
• Signalling to TAUA general signalling mechanism has been developed for AXE Access 910. This “transport function” is referred to as ICS, Internal Communication Service. The RPG is used for this type of signalling too.
• Signalling to EMRP software in AUSThis type of signalling is used to send orders to the functions implemented in the hardware in the AUS (for example, time switch, digit reception, tones, and I/O). The RPG is used for this type of signalling as well (STC and STR in the old SSS5 structure).
Figure 2.14 shows the hardware required in the local exchange for handling the V5.1 protocol, PRA access, the TAU communication, and the “STC-STR” signalling.
AXE Access 910
20
Figure 2.14Equipment needed in the local exchange to connect an AXE Access 910
The number of RPG in the local exchange is reduced due to the fact that each RPG has a large capacity and can in that way control several signalling links. As an example, one RPG can serve several access nodes regarding the TAU signalling. The RPGs are working in “n+1” redundancy. This means that one spare is used for a large number of RPG having the same functionality (e.g. one spare RPG for PRA signalling).
2.11 Improved CharacteristicsA large number of important improvements, relative to SSS5, have been made in the design of AXE Access 910. All figures and comparisons in the following list have been made in relation to the old SSS5 structure. The list contains the most important changes in characteristics; a complete list of all small changes and improvements cannot be made here.
2.11.1 Reduced FootprintIf compared with the old SSS5 structure, a reduction of footprint with a factor of 2.6 is achieved. The number of subscribers per node and the number of subscribers per subrack (magazine) is more in detail described in chapter 3. Figure 2.15 shows an example of a comparison.
ETC
ETC
ETC
ETC GroupSwitch
RPG AU V5
TAU
To/from AU
To/from TAU
To/from STR
ETC
ETC
ETC
ETC
CP-A CP-B
RPB
in AUS
V5
ICSRPG
STC-STR
ETC RPGTo/from PRA ETCV3 PRA
RPG
System Overview
21
Figure 2.15Reduction of footprint
2.11.2 Reduced Power ConsumptionThe power consumption has been reduced by some 40% for PSTN subscribers. Reduced power consumption also means reduced need for cooling, reduced costs for both power and cooling, and, in the end, that gives a lower cost of ownership for our customers.
2.11.3 Improved ISP, In Service PerformanceThe reduced number of circuits and improved design have improved the availability of the system considerably. Here are some figures supporting this statement:
• For an access node with mixed PSTN and ISDN-BA of some 2000 subscribers/B-channels, the MTBF is 0.5-0.6 years (6-7 months).
• The AUS has a failure rate of 79 years (Mean Time Between System Failure). For an access node of 2000 subscribers/B-channels having 5 AUSs, the MTBSF is then 16 years.
• The MADT, Mean Accumulated Down Time, is calculated to 5 minutes per year for a node having 200 PSTN subscribers. This figure is calculated on faults caused by hardware faults. The corresponding figure for SSS5 is 12.4 minutes.
• With the optional function equipment protection switching, the MADT is improved with a factor 14 (from 5 minutes down to 0.35 minutes).
2.11.4 Fewer Board TypesA reduction in the number of board types lowers the cost of spare parts for our customers. This will affect the “cost of ownership”, as less spare parts will reduce costs and capital tied up.
4 x LSM 6 x LSM 6 x LSM = 2 048 PSTN
= 3 000 PSTN
400
720
400
600
720 720
600
4 x Subrack 4 x Subrack
2 370 PSTN lines per m2
6 550 PSTN lines per m2
Reduction of footprint by factor 2.6
AXE Access 910
22
2.11.5 New Hardware FunctionalityThe hardware contains functions which enable the boards to be identified. Upon command, the operator gets product identity, revision information, serial number as well as position in the access node. Visual fault indication by means of LED is also provided. This will simplify the maintenance and reduce the risk of faulty handling.
2.11.6 Traffic CharacteristicsThe AUS Network has better traffic capacity than the old TSB, time switch bus. This makes the AXE Access 910 less sensitive to uneven traffic loads.
There are more keyset receivers (KRC) in the AXE Access 910 per subscriber than in the old SSS5.
23
3. Hardware Structure, BYB 501
3.1 Chapter IntroductionThis chapter will give you an overview of the building practice used in AXE Access 910. The building practice has many advantages for the customer and it gives future-proof and flexible mechanics adapted to future broadband services.
3.2 BYB 501, a New Building Practice
3.2.1 IntroductionAXE has always had a certain building practice for our telephone exchanges. For AXE, the building practice is given an ABC class, BYB. During the many years of AXE, there has been three different building practices in use:
• BYB 101This system was used between 1976 and 1986. Based upon racks and magazines to hold the printed circuit boards.
• BYB 202Still in use today (the blue cabinets) for some parts of AXE. Ericsson’s main building practice for AXE exchanges between 1986 and 1998.
• BYB 501The latest building practice optimized for the new compact hardware.
The main features of BYB 501 is that it complies with IEC and ETSI standards. This means that most supplier’s equipment can be mounted directly in the mechanical structure without any modifications. This includes equipment based upon 19 inch racks (common in the computer industry).
After completing this chapter, you will be able to:
• Describe the new building practice used: BYB 501
• Describe how the mechanics is built-up and structured as well as some important metrics
• Account for the main functions implemented in the hardware of the system.
Chapter Objectives
AXE Access 910
24
3.2.2 CabinetsBYB 501 can be built in many different sizes and the size used in Access 910 can be seen in Figure 3.1. Other sizes in BYB 501 are 2200 mm height and depth of 300 mm.
Figure 3.1Cabinet size in Access 910
Cabinets can be placed in different ways depending on the requirements from the customer. Figure 3.2 shows three different alternatives for arrangements of cabinets.
Figure 3.2Possible arrangements of cabinets
3.2.3 SubracksSubrack is the term used in BYB 501 instead of “magazine” which was used in BYB 202. The subrack in BYB 501 is much more flexible than the magazine in BYB 202. Plug-in units of various sizes may be used in one and the same subrack.
1800
400600
400
600
Back-to-wall
Free-standingsingle row
Back-to-back andthe possibility tohave double-depthcabinet
Hardware Structure, BYB 501
25
The standard subrack in BYB 501 is 450 mm wide and it can house up to 21 plug-in units with 20 mm spacing. There is also a half-width subrack available if needed (e.g. APZ 212 25). Figure 3.3 shows the basic dimensions of the subrack used in Access 910.
Figure 3.3Basic dimensions of a subrack
The subrack is of product type BFD 518 and the backplane is of product type ROJ 605.
3.2.4 CoolingCooling for access products is important as much heat is generated by the line circuits. The main reason for the generated heat is the current feed of the subscriber lines. In case of short subscriber lines, most of the energy is heating the line circuit itself.
The cooling principle used in Access 910 is based upon forced cooling using fans and a combination of serial and parallel cooling. Figure 3.4 shows the main principle.
485 250
300
AXE Access 910
26
Figure 3.4Cooling principles of BYB 501 when used in Access 910
It can be seen from the figure that the subracks are cooled by means of a fan that cools two subracks. The other two are cooled by another fan. Two subracks are cooled in series.
3.2.5 Cabling in BYB 501 in GeneralCabling is done by means of cable shafts at the side of the subracks inside the cabinet. From the cable shafts, the cables are put on cable shelves and then up to the connectors on the front of the board. All cabling is done from the front. Figure 3.5 shows the cabling area when looking at the cabinet from above.
Cable shelfFan
Air intake
Air flow
Chimney
FrontAir guiding plate
Fan
Air intake
Sub-rack
Back
Hardware Structure, BYB 501
27
Figure 3.5Cabling area when looking at the cabinet from above (cross section)
From the cable area at the sides of the cabinet, the cables are guided to the correct PCB via the cable shelf. There is one cable shelf for each subrack located just below the subrack. Figure 3.6 shows the main principle of the cable shelf.
Figure 3.6The cable shelf and one connector, side view
3.2.6 Electromagnetic Compatibility, EMCOne of the main objectives in developing the BYB 501 was to create a system with excellent electromagnetic compatibility (EMC). EMC is defined as: “the ability of the equipment to function satisfactorily in its electromagnetic environment without introducing intolerable electromagnetic disturbances in that environment.”
By means of shielding subracks, cables, plug-in units and components, the BYB 501 equipment practice further improves a system’s EMC characteristics. The connection of cable shields at the front of a plug-in unit is extremely important to the system’s EMC performance. It is
Subrack
Cabling areaFront
Back
Connectors
Cable shelf
Connector
AXE Access 910
28
important to keep the cable from acting as an antenna for radiation to and from the system. Similar requirements apply to the earthing of filters for unshielded cables.
No requirements for shielding have been imposed on cabinets. Instead, all shielding functions have been allocated to the subrack level. There are two main reasons for doing so:
• Subracks installed in customer cabinets meet requirements for EMC without the need for further protection or re-design.
• Cabinet doors can be opened during maintenance work without causing the stipulated emission limits to be exceeded.
Figure 3.7 shows the design of a single subrack and the parts that have been specially adapted to the EMC requirements.
Figure 3.7Shielding of a subrack (top view)
3.2.7 Power DistributionBYB 501 uses two-step high-ohmic distribution (TS-HOD), which minimises the effects of short-duration voltage transients (spikes) produced by short-circuit currents. The power is distributed to all plug-in units in the subrack from the two Distribution Units (DU-2 boards) located to the left side in the subrack. All plug-in units gets current feed from both DU-2s as can be seen in Figure 3.8.
Backplane
Subrack shield
Shielded front panelShielded cable and connector
Components shieldingcoverP
IU
Hardware Structure, BYB 501
29
Figure 3.8Distribution of power to all plug-in units
The backplane is used to distribute the -48 volt to all plug-in units within the subrack. There are two separated distribution systems in the backplane. This allows for failure in one system without having any power failure in any part of the subrack. Figure 3.9 shows the main principle and how the power is distributed in the backplane to all units.
Figure 3.9Power distribution within a subrack
3.2.8 Mechanical KeysTo avoid that some boards end up in a not allowed subrack position, the printed circuit boards are equipped with a “mechanical key”. This makes it impossible to fully insert a printed circuit board in a position not allowed. Some combinations of backplane and printed circuit boards will damage the latter. Please study the table below.
DU
-2 #
AD
U-2
#B
- 48VPlug-in Unit
DC/DC convertere.g. 5 V=
=
DU-2 #ASlot #29
DU-2 #B
Subrack
Slot #30
#1 #8 #9 #16
A
B
to slot #1 to #8
to slot #9 to #16
A
B
to slot #1 to #8
to slot #9 to #16
A A
B B
- 48 V
AXE Access 910
30
3.2.9 Miscellaneous about BYB 501The following could also be added to the description of BYB 501
• Environment managementThe mechanics, and plastics, fulfil existing as well as anticipated environmental requirements.
• Handling and installationWith BYB 501, the installation time can be reduced as the mechanics permit fully equipped and tested cabinets to be delivered to the installation site. Earthquake resistance can be maintained with additional strengthening elements securing the cabinets to the floor.
• Cable distribution systemThe cable distribution system is either mounted above the equipment in cable trays, or below the equipment in raised floor. Optical fibre cables and AC power cables may be separated in separate routes.
3.3 Subracks in AXE Access 910
3.3.1 MUS, Multiple Access Unit SwitchThis subrack contains the switching part of the Access 910 as all the AUS boards are located in this magazine. The AUS boards contains all common equipment as well as the switch. The 2 Mbit/s lines from the connected AUs are connected via the AUS-C board. There are different configuration alternatives available and only one can be explained in this chapter. Figure 3.10 shows one variant of the MUS subrack.
Board Key #5 Key #4 Key #3 Key #2 Key #1 No key
AU X
AU-EP X
AU-EPS X
AUS X
AUS-EP (C) X
TAU X
TAU-C X
ET X
AU ADSL X
AU Filter X
Hardware Structure, BYB 501
31
Figure 3.10One variant of the MUS subrack
Up to 6 AUS can be housed in the subrack. If AUS protection switching is implemented, a spare AUS is needed in position 13. The subrack is prepared for having narrowband AU (access units) in position 1-15. This means that AUS and AU can be mixed within the subrack.
3.3.2 NBA, Narrowband Access SubrackThe narrowband access subrack is used to connect subscribers with POTS and ISDN service. Different AU boards will be used for POTS and ISDN-BA access. Figure 3.11 shows one configuration alternative for the subrack.
Figure 3.11Narrowband access subrack, NBA
Almost the whole subrack is filled with Access Units of type POTS or ISDN. Position 15 has a TAU or a 15:th AU. If no TAU is located in the subrack, a TAU in another subrack measures the AUs via cables going to the TAU-C board. AUs for POTS or ISDN-BA can be mixed in the subrack. Here are some examples of capacities:
AU
S C
DU
-2A
US
-5
AU
S-0
AU
S C
[AU
S s
pare
][T
AU
spa
re]
TAU
TAU
-C
DU
-2#
1#
2
# 11
# 12
# 13
# 14
# 15
# 16
AU
-1
DU
-2A
U-0
AU
-10
AU
-11
AU
-12
AU
-13
TAU
or A
U-1
4TA
U-C
DU
-2#
1#
2
# 11
# 12
# 13
# 14
# 15
# 16
AXE Access 910
32
The number of TAU used in the cabinets is determined by how often the customer would like to do line measurements. As indicated in the text above is it possible to have a TAU common for many subracks. The TAU-C boards are interconnected by means of a cable. The cable contains the following:
• A serial RS 485 bus for connection to AU processors (control test access bus, ACOM)
• Test access bus for measurements of line and LIC• Protection switching bus (LCOM)• PULSI extension bus, PEBUS
3.3.3 MUA, Multiple Access SubrackThe multiple access subrack has been developed to meet the demands of mixed access types in one and the same subrack. From an operator’s perspective, it is important that the hardware allows to slowly add more and more broadband accesses. It is difficult for operators to predict where and when subscribers wish to change from narrowband to broadband access. Figure 3.12 show the possible combinations of boards.
Figure 3.12Configuration of MUA subrack
It can be seen from the figure that it is possible to mix narrowband AUs, for POTS and ISDN-BA, and the broadband AUs in the same subrack. For
AU for POTS AU for ISDN No. of subscribers
15 0 450
14 0 420
13 1 390 + 15
12 2 360 + 30
11 3 330 + 45
AU
/ E
T (s
) / F
ilter
DU
-2A
U/E
T
AU
/ ET
(s) /
AD
SL
AU
/ E
T (s
) / F
ilter
AU
... o
r TA
UTA
U-C
DU
-2#
1#
2
# 13
# 14
# 15
# 16
AU
/ ET
(s) /
AD
SL
# 3
Cell-bus(pos 1-15)
Hardware Structure, BYB 501
33
ADSL lines, a filter board is required. This means that there are minimum two boards required for ADSL access. The cell-bus, which runs in the backplane of the subrack, is used to interconnect the ADSL boards with the ET. The first versions will have 4 subscribers per board pair for ADSL access. In the future, there will be 8 subscribers per board pair. This means that the following configuration alternatives are possible (it is assumed that there is a TAU in position 15):
3.3.4 SIS, Single Switch Subrack (used in out-door version and Ericsson Access 910)The single switch subrack is, as the name indicates, one complete access node in one and the same subrack. This means that AUS, TAU and AUs have to be located in the same subrack. The subrack is also optimized for the so called Outdoor-Midi cabinet. Figure 3.13 shows how one SIS subrack could look like.
Figure 3.13The layout of the SIS subrack
The AUs, or filter/ADSL boards can be mixed in the positions 1-12 in case of AXE Access 910 (can only be connected to an AXE exchange). In case of a generic access node (Ericsson Access 910), the ASC board is required.
AU for POTS AU for ISDN AU for ADSL No. of subscribers
14 0 0 420
10 1 1 300 + 15 + 4 (8 in 2:nd rel) =319
8 1 2 240 + 15 + 8 (16) = 263
6 1 3 180 + 15 + 12 (24) = 207
4 1 4 120 + 15 + 16 (32) = 151A
U/E
T/F
ilter
DU
-2A
U/E
T
AU
/AS
CA
US
AU
S-C
TAU
TAU
-C
DU
-2#
1#
2
# 12
# 13
# 14
# 15
# 16
AU
/ET(
s) /A
DS
L#
3
Cell bus(pos. 1-11)
AXE Access 910
34
3.4 Cabling Inside Access 910Access nodes contains many cables as subscribers are connected to these nodes. There are two wires required for each subscriber and there are additional cables needed to interconnect subracks with test buses and 2 Mbit/s lines. It is not possible to describe all cables and how all subracks are interconnected so one important example is described. Figure 3.14 show how subscriber lines are connected to the AU and how the AUs are connected to the AUS-C. From the AUS-C, the E1 links to the local exchange are connected to the DDF, digital distribution frame, via a connection field, CCF.
Figure 3.14Cabling inside Access 910, example with one AU and one AUS and only one cable of each type shown
The TAU-C board, always located to the very right in the subrack (in position 16), has cables inter-connecting then different TAU-C boards with each other. The interconnection makes it possible for one TAU to control and perform measurements in other subracks. The inter-connection contains:
• ACOMThe main communication link between the TAU and the AUs. The bus continues in the backplane of the subrack to all AUs within the subrack. The bus is a serial bus (RS 485).
• LCOMThis is the bus that makes it possible for the TAU to control the optional function equipment protection switching. The bus
AU
S-C
AU
MUS
NBACCF
To MDF
To DDF
AU
S2 Mbit/s from AUto AUS
2 Mbit/s from AUSto CCF, DDF andLocal Exchange
30 subscriber lines
Hardware Structure, BYB 501
35
interconnects the TAU with the AUS-EP and AU-EP. Also this bus continues in the backplane of the subrack.
• Test AccessThe test access connection. This bus inter-connects the measurement equipment on the TAU with the AU. Also this bus continues in the backplane of the subrack.
The inter-connection between the TAU-C boards can be seen in Figure 3.15.
Figure 3.15Connection of TAU-C boards within one cabinet
The TAU-C board also contains logic for fault indication by means of a LED located on each board in the subrack (this is valid for all types of subracks). Figure 3.16 shows how the TAU-C is connected to the LEDs.
TAU-C
MUS
NBA/MUA
NBA/MUA
NBA/MUA
TAU
TAU
TAU
TAU
Bus termination
Bus termination
AXE Access 910
36
Figure 3.16Fault/service indication
3.5 Printed Circuit Boards
3.5.1 Access Unit for PSTN, AUP3The AU board is the new board used to connect ordinary PSTN subscribers to the AXE Access 910. Basically, it contains the same functions as the former LIC board in SSS5, holding 4 or 8 Line Interface Circuits. However, due to increased board size and new building practice, it is possible to connect 30 PSTN subscribers to one AU board. The board contains the following functions:
• Current feed of the subscriber line can be programmed to be 2 x 400 ohms resistive feed or 30 mA constant current
• Ring signal and ring trip (up to 90V and frequencies set to 16, 20, 25 or 50 Hz)
• Detection of off-hook (loop closures)• Analogue to digital conversion and digital to analogue conversion• 2- to 4-wire conversion• Software controlled input impedance, balance impedance and levels• V5.1 interface• Over-voltage protection of the subscriber lines• Control of the test access relays.
The board is built up around 4 basic parts:
1. LI, line interfaceA line interface built up with two integrated circuits referred to as SLIC (Subscriber Line Interface Circuit) and QSLAC (Quad Subscriber Line Audio processing Circuit)
2. NT, network terminalA network terminal terminating the 2 Mbit/s link between the AU and the AUS
3. AUC, access unit controllerA processor with memory and I/O ports
Backplane
TA
U-C
PIU
PIU
PIU
Hardware Structure, BYB 501
37
4. POW, powerA power unit which also generates ring current and, optionally, signals to private meters.
Figure 3.17 shows a simplified block diagram of the board.
Figure 3.17The AU board for PSTN access, AUP3
The processor has two memory types:
• Flash memoryThis memory is used as a local backup instead of reloading all software from the CP in case of start-up or reload. This will make restarts faster.
• RAM memoryWhen the processor is started or restarted, the contents of the Flash memory is copied to the RAM memory for normal program execution.
The I/O ports connected to the processor have the following functions:
• Board positionThe position of the board in the subrack is given to the processor. Fixed for the address within the subrack and via a switch for subrack address.
• PBIST, processor based built-in self testThis interface is a standard RS232 (V.24) interface used during manufacturing test. The interface can also be used for local trace and debug.
• ACOMThe interface is a serial interface (RS485) which interconnects the AUs
SLIC
SLIC
SLIC
SLIC
SLIC
SLIC
QSLAC NTSpeechSynch.
Data
T.16
1
2
3
4
30
POW
AUC
SLIC
SLIC
SLIC
SLIC
~~
~
~
~
~
QSLAC
Flash
RAM
I/O
Board position
~~
~
RG + PRM-48V
-32V or -48V +5V
To/fromAUS
HDLC
(processor)
LI
PBIST (RS232)ACOM (RS485)
TAU(TestAccess)
AXE Access 910
38
to a TAU. The TAU can send orders related to Subscriber Line Maintenance of software upgrades via this interface.
The functions for one subscriber line can be seen, in a simplified way, in Figure 3.18.
Figure 3.18Functions for one subscriber
The SLIC performs the 2- to 4-wire conversion and the QSLAC performs analogue to digital conversion (and vice versa).
3.5.2 Access Unit for ISDN BAThere is one specific AU (Access Unit) board developed for connecting ISDN subscribers to AXE Access 910. The board can connect 15 ISDN basic access subscribers in accordance with ETSI standard ETR 080. The differences between the AU PSTN and the AU ISDN are, at this level, not very great. They use the same Network Terminal and a similar bus structure. The main differences are:
• Another LIC implementation is used, with two circuits specially developed for ISDN BA.
• Another processor is used due to higher demands for processing capacity.
• A slightly different power supply is used as no ring current is connected to the line interface.
Figure 3.19 shows the main features of the hardware.
TAU
Overvoltageprotection
Ringrelay
Ringingsignal
SLIC
Batteryvoltage
Data
Speech QSLACSpeech
(TestAccess)
Hardware Structure, BYB 501
39
Figure 3.19The AU board for ISDN access
I/O from the AUC is the same as for the PSTN board. Please study section 3.5.1 on page 36.
The hardware for ISDN subscribers comprises not only the Line Interface Circuit (LIC) but also an HDLC (high level data link control) which handles the D-channel. The D-channels and the V5.1 signalling are multiplexed into channel 16 and taken care of by the RPG in the local exchange.
3.5.3 Access Unit for ADSLThe line boards for broadband access is based upon the internationally standardized ADSL technology. This gives up to 8 Mbit/s to the subscriber and up to 1 Mbit/s from the subscriber. The line boards have 4 ADSL modems which can be working in so called “Full Rate ADSL” or “Lite” mode. The latter is an application giving 1.5 Mbit/s to the subscriber but a cheaper installation without splitters on the subscriber side. The main function blocks of the line board can be seen in Figure 3.20.
LIC
LIC
LIC
LIC
NTSpeech and/or dataSynch.
Data
T.16
1
2
15
POW
AUC
Flash
RAM
I/O
-48V+9V +5V-97V
To/fromAUSLIC
LIC
HDLC
LI
Board positionPBIST (RS232)ACOM (RS485)
TAU(TestAccess)
AXE Access 910
40
Figure 3.20Functions of ADSL line board
3.5.4 Filter for ADSLEach board contains 4 filters (splitters) which are used to separate the narrowband PSTN traffic from the broadband traffic. The POTS band frequency range is set to 300 - 4000 Hz.
3.5.5 AUS, Access Unit SwitchThe AUS has already be described in great detail in chapter 2. The front of the AUS has some connectors for connector of a local debugger (software on EMRT-T) and the duplicated synchronization ring.
3.5.6 AUS-CThis board connects all cables, except for the synchronization ring, that are connected to the AUS. Figure 3.21 shows all the cable positions at the front of the AUS-C.
ADSLModem
ATMCore
BoardController
Cell BusInterface
Power
ADSLModem
ADSLModem
ADSLModem
2
-48V
CellBus
2
2
2
Hardware Structure, BYB 501
41
Figure 3.21Cables connected to the AUS-C (front of AUS-C shown)
3.5.7 TAUThe following measurements can be performed by the TAU:
• Measurement of resistance, capacitance and voltage on the subscriber line.
• Measurement of voltage and current feed from the Line Interface Circuit.
• The TAU can simulate subscriber actions such as off-hook and on-hook and then verify that these actions are detected by the Line Interface Circuit.
• Measurement of decadic digits (pulse/pause ratio).
RST-0
RST-1RST-2RST-3RST-4RST-5
AU-0AU-1
AU-2AU-3AU-4AU-5AU-6AU-7AU-8AU-9AU-10
AU-11AU-12AU-13AU-14
alt. AU-15alt. AU-16
alt. TAU
Mesh
not usednot used
MeshMeshMeshMesh
Maximum 6 E1 links to/fromlocal exchange.Less in case of low traffic.
Maximum 15 AUs connectedto one AUS. If low traffic (less than0.23E) up to 17 AUs per AUS.
Mesh network inter-connectingall AUSs
2 E1 links not used
AXE Access 910
42
• Measurement of the private meter signal and ring signal sent from the AU.
• Test of the ISDN subscriber line.
Figure 3.22 shows the main structure of the TAU board.
Figure 3.22The main structure of the TAU board (note, only one AU shown as an example)
The “test head” is the actual measurement equipment in the TAU. It is this unit that performs the measurements of the subscriber line and the subscriber’s Line Interface Circuit. The test head consists of:
• A multimeter instrument including a micro controller and analog measurement circuits.
• Relays connecting the measurement circuits to the subscriber line or the line circuit via the analog test bus.
• A serial link to the main processor system. The link is an optical link, as the analog test circuits should be galvanically separated from the other parts of the board.
3.5.8 TAU-CThe board TAU-C is a connection board which connects all cables to the TAU board. The TAU-TAU-C connection is done in the backplane of the subrack. The cabling of TAU-C is explained in Figure 3.15.
Test Access Bus
AU
Power
NT
ProcessorI/O
To/fromAUS
Test Head
LIC
Processor
Data
ACOM
(T/A bus)
TAU
(RS 485)
43
4. Software Structure
4.1 Chapter IntroductionThis chapter will give you an overview of AXE Access 910 software structure. The basic structure is explained as well as the set of parts (CRT). Important function blocks involved in traffic handling which provide insight into the functions inside the system will also be explained.
4.2 Set of Parts, CRT levelSSS, Subscriber Switching Subsystem, is divided into a number of “sets of parts”. The ABC class for a set of parts is CRT. Each set of part is further divided into function blocks (CNT) and hardware function units (COA and BFD). Under each function block, there is one or several software modules (CAA). Figure 4.1 shows the general structure.
After completing this chapter, you will be able to:
• Describe the general system structure of AXE Access 910
• Give a short description of the three set of parts (CRT) created to implement AXE Access 910.
Chapter Objectives
AXE Access 910
44
Figure 4.1System structure
The following set of parts are unique for AXE Access 910:
• AUV5, Access Unit V5 Application• MAUS, Multiple Access Unit Switch• MAOAM, Multiple Access, Operation, Administration and
Maintenance.
The set of parts SWITCH and SLM (subscriber line maintenance) are also used for the existing SSS5 product. For example, subscribe line maintenance functions are basically the same in both product variants.
4.3 Access Unit V5 Application, AUV5Access Unit V5 Application, AUV5, is the set of parts within subsystem SSS that handles physical connection and traffical functions for PSTN and ISDN-BA subscribers connected to the Multiple Access Group (MACCG).
The central application functions are:
• Protocol handling for Control and PSTN protocols.• System management for the V5.1 interface.• Traffic handling functions for ISDN-BA and PSTN connected
subscribers.• Measurement of line down time for PSTN access.
AXE
APT
Equipped ANT (SSS)
AUV5 MAUSSWITCH SLM
MAOAM
CNT
NBAMAU
MUS
Cabinets
Access Functions Switching Functions Maintenance Functions
CRT CRT CRT
COA/BFD CNT COA/BFD CNT COA/BFD
MACCG
SIS
Software Structure
45
• Private metering for PSTN subscribers.• Connection, disconnection and maintenance of internal signalling
paths.• Redundancy switch over of STs.• Communication channel concentration.• Measurement of line down time for ISDN-BA and PRA accesses.
The remote PSTN application functions are:
• Protocol handling for control and PSTN protocols.• System management for the V5.1 interface.• Current feeding of the subscriber line.• Analogue to digital conversion.• Subscriber line signalling.
The remote ISDN-BA applications are:
• Protocol handling for the control protocol.• System management for the V5.1 interface.• Current feeding of the subscriber line.• ISDN-BA Layer 1 (2B1Q).
4.3.1 Blocks for PSTNThe blocks in the set of parts AUV5 for PSTN can be seen in Figure 4.2
Figure 4.2Blocks in AUV5 for PSTN
Hardware
Load
AUPSTN
Local Exchange
Module
AXE Access 910
DLAU CTRLAU PSTN
DLAU CTRLAU PSTN
AUPSTN
LIMALIAU CPRM
V5.1
Central Software
Regional Software
HardwareRPG
in EMRP-T
GAM SAH
GAM
SAH
AXE Access 910
46
• AUPSTN, Access Unit PSTN. The function block AUPSTN is divided into a number of sub software units (CAY). Each CAY is assigned specific functions for configuration, traffic handling, maintenance, measurements, etc. The main functions handled by AUPSTN are:
− Current feeding of the subscriber lines.− Analogue to digital conversion.− Line signalling.− Digit reception.− AU V5.1 System Management and Layer 3 of the Control
protocol.− AU PSTN V5.1 Layer 3 port control protocol.
• DLAU, Data Link Layer V5. The function block DLAU is the data link layer handling block for V5.1. It implements the envelope function, the mapping function, the flow control function and the data link handling.
• CTRLAU, Control Access Unit. The function block CTRLAU performs message and protocol handling of the control protocol messages that are conveyed over a V5.1 interface. It implements the V5.1 system management functions and performs the data link management for the control and PSTN data links.
• PSTN, PSTN protocol handler. The function block PSTN performs message and protocol handling functions for the PSTN layer 3 messages that are conveyed over the internal V5.1 signalling interface.
• CPRM, Central Private Metering. The function block CPRM is a command handling block which handles Private Metering connections. The block has commands for connection of Private Metering, disconnection of Private Metering and printing information about Private Metering connections.
• GAM, Generic Access ManagerThe block allows the operator to connect, disconnect, and maintain signalling channels. In the case of Access 910, GAM is used for V5 and V3 signalling channels.
• SAH, Stand-alone HandlerThe block handles PSTN emergency traffic if the control link to the local exchange is out of order (blocked due to a fault). The block has central software and regional software in the EMRP.
4.3.2 Blocks for ISDN-BAThe blocks in the set of parts AUV5 for ISDN-BA can be seen in Figure 4.3
Software Structure
47
Figure 4.3Blocks in AUV5 for ISDN-BA (not all interfaces shown)
• AUBA, Access Unit Basic Access. The function block AUBA is divided into a number of sub-software units (CAYs). Each CAY is assigned specific functions as configuration, traffic handling, maintenance, measurements, etc. The main functions handled by AUBA are
− ISDN Layer 1− AU System Management and Layer 3 of the Control protocol.− ISDN Layer 3 port control protocol for the AU board.− AUBA consists of remote software (AUC) and hardware.
• DLAU, Data Link Layer V5. The function block DLAU is the data link layer handling block for V5.1. It implements the envelope function, the mapping function, the flow control function and the data link handling. It also maintains the L2 supervision and statistics function for Basic Accesses and participates in the signalling terminal board supervision.
• CTRLAU, Control Access Unit. The function block CTRLAU performs message and protocol handling of the Control Protocol messages that are conveyed over a V5.1 interface. It implements the V5.1 system management functions and performs the data link management for the Control and PSTN data links.
• MANAU, Management Basic access Access UnitThis function block handles management of terminal end point
Hardware
Regional
AUBA
Local Exchange
Software
AXE Access 910
DLAU CTRLAU MANAU
DLAU CTRLAU MANAU
LIBAMALIAU
V5.1
MHAU
MHAU
RPG
Regional Software
Central Software
Hardware
in EMRP-T AUBA
LIHHLIHHX PSTNHMA
AXE Access 910
48
identification, layer 2/layer 3 interwork and layer 3 supervision and statistics.
• MHAU, Message Handler basic access Access UnitThe function block buffers and analyses the layer 3 messages coming from the user. MHAU also builds layer 3 messages in the network to user direction.
• LIAU, Line Interface Access UnitThe block acts as an interface for the GAM and it contains administration of user ports and bearer channels as well as blocking and deblocking of the interface.
• LIBAMA, Line Interface Basic Access Multiple AccessThe block is the device owning block for the BA devices and contains subscriber line functions. Examples of functions are blocking and deblocking, subscriber data administration and traffic handling.
• PSTNHMA, PSTN protocol handler for PSTN over ISDN-BAThe block is used for the function PSTN over ISDN-BA. The block contains the interface to the hardware for PSTN traffic or “home-highway access”. The block consist of central and regional software.
• LIHHThe block is used for the function PSTN over ISDN-BA and is the device owner for the PSTN part. It supports the so called H-link.
• LIHHXSimilar function as LIHH but for the so called XSS part (existing source system).
4.3.3 Blocks for GS Connected EquipmentThere are three blocks in AUV5 that have hardware connected to the Group Switch. Basically, all blocks are used to send information to the subscribers. Figure 4.4 shows the hardware and the blocks.
Figure 4.4Blocks in AUV5 for group switch connected equipment
Hardware
Local Exchange
CSKD
Regional Software
Central Software
CSR-D CSKD CSFSK
CSKD
CSR-D
CSR-D
CSFSK
CSFSK
Software Structure
49
• CSR-D, Code Sender/Receiver DigitalThe hardware sends MFC signals which can be used to send signals to older PABXs. The hardware has 16 devices and it is connected to the Group Switch.
• CSKD, Code Sender, DigitalThe hardware sends DTMF signals to the subscribers. It may be used for Direct In Dialling towards PABXs or towards subscribers in some markets. The hardware has 32 devices and it is connected to the Group Switch.
• CSFSK, Code Sender FSK signallingThe hardware sends FSK (frequency shift keying) signals to subscribers. Many markets use this function for A-number presentation (CLIP, calling line presentation). The hardware has 32 devices and it is connected to the Group Switch.
4.4 Multiple Access Unit Switch, MAUSThis set of parts implements the functions needed for the AUS, Access Unit Switch. Functions implemented are:
• Administration of the AUS hardware and fault supervision• Switching functions between connected ET interfaces and the internal
DSP device (digital signalling processor implementing KRC and tone sending)
• Keyset receiver and tone sending from the DSP• Concentration of V5.1 signalling channels, so called C-channels• Administration of different applications which can be connected to the
platform.
The blocks included in MAUS can be seen in Figure 4.5.
AXE Access 910
50
Figure 4.5Blocks in MAUS
The blocks have the following functions:
• ANH, Access Network HandlerThis block owns and handles the AUS Network interconnecting all AUSs in the same access node. The block seizes time slots and performs traffic measurements.
• AUS, Access Unit SwitchThis block is the hardware owner of the AUS board and it co-ordinates administration, configuration, and maintenance for other blocks. Functions such as network node, DIP and device administration, and clock handling are also performed by the block.
• DIPHID, Digital Path Historical DataThis block stores quality supervision data (logging of data received from DIPST).
• DIPST, Digital Path Supervision and TestThe block handles the DIPs between the access node and the local exchange.
• ET, Exchange TerminalThere are two variants of ET blocks in the set of parts:
− ET for the access node side taking care of hardware supervision and test of the ET circuits on the AUS board.
− ET for the local exchange side taking care of the same things but for the ETs located in the local exchange.
TSMT
TS
ANH
KRT
AUS
ET
AUSTS KRT ET ET
ET
Central
Hardware
Regional
Local Exchange
TSMT
TS
ANH
KRT
AUS
ET
AUSTS KRT ET
ETC
ET
ET
Software
Software
DIPSTDIPST
ETDIF
in EMRP-T
Regional Softwarein RP
DIPHID
RST155
RST
AUS Board
Software Structure
51
• ETDIF, Exchange Terminal InterfaceThis is an interface block adapting the RST block to the standardized ET interface used in AXE.
• KRT, Keyset code Receiver and Tone sendingThis block is the merged KR2 and SSTONE and takes care of keyset code reception and tone sending.
• RST, Remote Stage TrafficThis block owns the traffic channels in the 2 Mbit/s lines between the access node and the local exchange. The block also interworks with the GAM, Generic Access Manager, platform when selecting time slots for signalling (e.g. V5).
• RST155, Remote Stage Traffic, 155 Mbit/sSame as for RST but handles the 155Mbit/s interface between the local exchange and the Access 910.
• TS, Time SwitchThe block connects and releases paths in the time switch in the AUS.
• TSMT, Time Switch MaintenanceThe block administrates some operation and maintenance functions related to the time switch.
4.5 Multiple Access, Operation, Administration and Maintenance, MAOAMThis set of parts contains functions for operation and maintenance related to AXE Access 910. The main features are:
• Command interface for configuration of the system for maintenance• A communication service (ICS) for communication between
applications in the CP and applications in the TAU or AU• An interface to the GAM platform for connecting the TAU• TAU handling in general.
The set of parts consists of 15 blocks as depicted in Figure 4.6.
AXE Access 910
52
Figure 4.6Blocks in MAOAM
The main functions of these blocks are:
• MXTAU, Message Multiplexer, TAUThis block is the layer 3 message handler for messages between the CP and the TAUs.
• DLTAU, Digital Line TAUThis block handles layer 2 messages between the TAUs and the RPGs. The block is implemented in regional and central software.
• TAUCMAN, TAU-C ManagerThe block is the hardware owner of the TAU-C board which contains functions for test access selection, external alarm connection as well as LED control.
• BBMAN, Broadband ManagerThe block is the hardware owner for the broadband hardware boards and the block makes it possible to define and remove hardware. The block maintains a list of all boards.
• MAADMC, MACCG AdministrationThe block handles the configuration commands for the MACCG as well as printout of exchange data.
AUMAN
DLTAU
MAADMC
TAUMAN
LITAU
ALTAU
AUSCORD
CTRLLEDFCMAH
NNADMC
PSHWCTL
TAUCMAN BBMAN
TEAU
MXTAU
MXTAU DLTAU
AUMAN
DLTAU
MAADMC
TAUMAN
RPG
LITAU
TAUHardware
RegionalSoftware
CentralSoftware
ALTAU
AUSCORD
CTRLLEDFCMAH
NNADMC
PSHWCTL
TAUCMAN BBMAN
TEAU
MXTAU
MXTAU DLTAU
Applications
AUSCORDAUCORD
Software Structure
53
• AUMAN, Access Unit ManagementThe block is the hardware owner of the AUs and it receives information about faults in the AUs and inserts/removes alarms. The block also handles the configuration of the AUs.
• NNADMC, Network Node AdministrationThe block handles all command related to the concept of Network Node (please study chapter 6).
• TAUMAN, TAU ManagerThe block is the hardware owner of the TAU and handles functions like configuration and blocking of the hardware.
• AUSCORD, Co-ordination of AUS Protection SwitchingThe block handles the co-ordination of protection switching for AUS within one access node (MACCG).
• AUCORD, Co-ordination of AU Protection SwitchingThe block handles the co-ordination of protection switching for AU within one access node (MACCG).
• PSHWCTL, Protection Switching Hardware ControlThe block controls the protection switching procedure.
• FCMAH, Function Change Multiple Access HandlerThe block is responsible for software upgrades of device processor software (processor software in TAU and AU processors)
• CTRLLED, Control of LED in MACCGThe block handles commands and printouts to configure the LED control function within an access node (MACCG).
• ALTAU, External Alarm HandlerThe block handles external alarms connected to the access nodes.
• TEAU, Test Manager for Access UnitsThe block is responsible for the tracing and debugging function within AU and TAU.
AXE Access 910
54
55
5. New Functions and Features
5.1 Chapter IntroductionThis chapter will give you information about functions in AXE Access 910 not described in any other chapter. For example, there are some specific AUS functions that are described here. However, the telephony-related functions described in chapter 2 will not be described again.
5.2 Hardware-Related Functions
5.2.1 Hardware IdentificationHardware identification enables each hardware unit (PCB, printed circuit board) to identify itself. Hardware identification is a standard function in BYB 501. This means that the each board can indicate:
• Product identity, for example ROJ 123 45• Revision information, for example R1A• Serial number• Physical location in the subrack, for example, 5.
The identification information is supplied to the AXE Hardware Inventory Management System which helps the operator keep track of the hardware installed at each site. This information makes operation and maintenance easier and cheaper as less manual inventory work is required. Figure 5.1 shows an example of a printout of an Access Unit.
After completing this chapter, you will be able to:
• Describe some important hardware functions in the new building practice used.
• Describe how equipment protection switching is implemented.
• Describe ADSL and SDH and how it is implemented in AXE Access 910.
• Describe the main functions and features of the new EMRP platform, EMRP-T
• Describe the different V5 functions in the system.
Chapter Objectives
AXE Access 910
56
Figure 5.1Example of printout of hardware inventory
5.2.2 Visual Fault IndicationAll Plug-In Units (PIU) have a visual fault indication on the board. The fault indication helps the repairman to pull out the correct unit when changing a board. Many fault situations in live exchanges are caused by human errors. The LED indication is made by small light emitting diodes (LED) having the following functions:
• Extinguished LEDThe unit is fault-free and should not be pulled out.
• Flashing LEDThe unit is faulty but not blocked. The unit should not be pulled out.
• Steady light from LEDThe unit is blocked and can be pulled out.
5.2.3 External AlarmsExternal alarms are used to indicate alarms from external sources, for example, fire, burglar, cooling and transmission alarms. These alarms are transmitted into the alarm system of AXE. This makes operation and maintenance easier as one common function receives all the alarms related to one site (for example one RSS in a basement of a large house). Up to 6 external alarms can be connected to each TAU-C (to the front of the board).
EXHWP:PIU=AUS-1;HARDWARE INFORMATION DATA
MACCG PIU PIUPOS RESULTTOWER AUS-1 2 EXECUTED
PRODUCTNO SERIALNO REVBFB 520 08/1 A87AAAEZLH R1A
HARDWARE SPECIFIC INFORMATIONINFO1
INFO2ROA 510 02/1
INFO3ROA 510 02/1
INFO4
INFO5
END
New Functions and Features
57
5.3 Equipment Protection SwitchingEquipment protection switching is a function which will significantly increase the reliability of the AXE Access 910 access nodes. The main idea behind the function is taken from transmission systems where one cable is active and the other is stand-by. When a fault occurs in an active unit, the stand-by is activated and replaces the faulty unit. The principles of protection switching in AXE Access 910 is to have spare units that can be connected in case of faults. The function can be used to:
• Increase In Service Performance by having redundant units in the system
• Introduce planned maintenance.
The two variants of the functions available in the system are described in the following two chapters.
5.3.1 Equipment Protection Switching of AUSThe main idea behind this function is to reduce the disturbances when an AUS gets faulty. The probability of an AUS of getting completely faulty (blocked) is low but when it happens, up to 450 subscribers cannot use their telephone.
Inside the MUS subrack, one of the AUSs will be a spare AUS. The AUS-C board will be replaced by a board referred to as AUS-EP (equipment protection). In the back plane of the MUS subrack, there is a protection switching bus which all AUS-EP connects to. Figure 5.2 shows the main principle.
Figure 5.2Main principle of AUS protection switching
Up to 28 E1
AUS-EP
ProtectionBus in back-plane of MUSsubrack
AUS
AUS Spare
28
Up to 28 E1
AUS-EP AUS
28
28
AXE Access 910
58
If an AUS gets fault, and blocked by the system, the AUS-EP will switch all E1 links to the protection bus in the backplane of the MUS subrack. As the spare AUS is connected to the protection bus, all E1 links previously connected to the faulty AUS is now connected to the spare AUS.
5.3.2 Equipment Protection Switching of AUThis function makes it possible to have protection switching on AU level. The main reason for having this function is to introduce “planned maintenance”. This means that a faulty unit can be replaced at scheduled visits to the site instead of almost immediately. The higher costs for the function can well be compensated by reduced maintenance costs for the operator.
The function is based upon a special subrack, having a protection bus in the backplane, and a new board type: AU-EP- The AU-EP connects all cables to the AU and it also has the ability to connect all 30 subscribers and the E1 link to the protection bus. The protection bus is wired with a cable between the subracks making it possible to have one spare AU of each type for the whole node (up to 3000 PSTN subscribers). Figure 5.3 shows how it is implemented and Figure 5.4 shows how a faulty AU is replaced by the spare AU.
Figure 5.3Main principle of AU protection switching
AU-EP AU
AU Spare
Protection Bus
Subrack A
Subrack B
30
E1
30 x LIC
AU-EP AU
30
E1
30 x LIC
AU-EP
30 x LIC
AU-EP AU
30
E1
30 x LIC
New Functions and Features
59
Figure 5.4One faulty AU is replaced by a spare AU
5.4 HDSL
5.4.1 General About HDSLHDSL, which stands for high-speed digital subscriber line, is a technology which makes it possible to have up to 2 Mbit/s digital transmission on a 4-wire copper cable. Note that HDSL requires 4 wires and not 2 as in ordinary subscriber access. HDSL makes it possible to connect digital PABXs via ordinary copper wires avoiding expensive coaxial cables or optical fibre cables. The distance depends on the quality of the copper wires. Here are some examples related to the existing HDSL product from Ericsson:
• Up to 3.5 km with 0.4 mm cable• Up to 6.0 km with 0.6 mm cable• Up to 8.5 km with 0.8 mm cable.
The interface will be a standard G.703 interface with a bit rate of 2.048 Mbit/s. Please study Figure 5.5.
AU-EP AU
AU Spare
Protection Bus
Subrack A
Subrack B
30
E1
30 x LIC
AU-EP AU
30
E1
30 x LIC
AU-EP
30 x LIC
AU-EP AU
30
E1
30 x LIC Blocked AU
AXE Access 910
60
Figure 5.5Example of an HDSL application
5.5 ADSL
5.5.1 General About ADSLADSL, which stands for asymmetrical digital subscriber line, was first specified in 1995. The term “asymmetrical” is used because the bit rate is higher in the direction towards the subscriber than in the other direction. Today, there are two main variants of ADSL on the market:
• “Ordinary” ADSL as first specified in 1995This gives up to 8 Mbit/s from the network to the subscriber and some 0.5 to 1 Mbit/s in the other direction.
• ADSL Lite specified in 1997The main idea is to create a “low-budget” ADSL which is easier to instal and thus cheaper for the subscriber. The technology allows up to 1.5 Mbit/s from the network to the subscriber
The exact bit rates are hard to specify as it depends on the quality of the access network. Many factors may affect the delivered bandwidth:
• cable type (diameter and isolation material)• length of the copper cable• loop structure in the access network• noise sources like crosstalk, impulse nose and radio frequency
disturbers.
The system components can, slightly simplified, be seen in Figure 5.6.
2 Mbit/s 4PABX
New Functions and Features
61
Figure 5.6Main principles of ADSL
The NT in the figure is a “Network Termination” and it contains the ADSL model as well as some interfaces such as Ethernet.
5.5.2 DMT, Discrete MultitoneDMT is the technology used by the ADSL modems. It means that the modem is actually using a large number of frequencies to transmit the data. Lower frequencies are not used as the telephone traffic will be sent there. If some frequencies are disturbed by the access cable, they are not used and the total bandwidth is reduced. Figure 5.7 shows the main principle of DMT.
Figure 5.7Main principle of discrete multitone, DMT
The number of sub-channels and their usage differs to some extent between ADSL and ADSL Lite. In the latter, there are only 128 sub-channels.
In ADSL, it is the filter that separates the POTS traffic from the broadband traffic. In Figure 5.7 it can be seen that the lowest frequencies are used by the POTS traffic and it is the task of the filter to separate the traffic. POTS traffic will be sent to the AXE local exchange and broadband traffic will
1.5 or 8 Mbit/s
0.3 - 1 Mbit/s
Video and TV(digital)
Telephony
Internet via PC
ATM, 25.6 Mbit/s
POTS/ISDN
Ethernet
NT
Bits/subchannel
Frequency
PO
TS
Upstream Downstream
Sub
chan
nel 2
55
1.1 MHz
Disturbance
AXE Access 910
62
be sent via an Exchange Terminal to a broadband network built-up by, for example, Internet routers. Figure 5.8 shows the main principle of the filter.
Figure 5.8The function of the filters
The main difference between ADSL and ADSL Lite is that the subscriber side in ADSL Lite can be without filter (or splitter). This simplifies the installation and can thus be a cheaper product for the operator and in the end the subscriber.
In ADSL, there are more things than simply DMT. Framing is done to keep track on bits used for traffic and operation and maintenance. There are synch words to keep track on the frames (compare with channel 0 in an ordinary 2 Mbit/s system).
On top of the physical layer, the ADSL layer, there is an ATM layer. ATM stands for asynchronous transfer mode and is developed by the telecommunications industry to support both real-time and non-real-time applications. ATM is based upon small packets referred to as cells. Each cell has a 48 byte pay-load and a 5 byte header. Within ATM, there are different protocols serving different types of applications. They are:
• ATM Adaptation Layer number 1, AAL-1This protocol handles constant bit rates. Circuit emulation and real-time video are examples of applications using this layer.
• ATM Adaptation Layer number 2, AAL-2This protocol handles variable bit-rate for services requiring real-time. An example could be coded speech at other bit rates than 64 kbit/s.
• ATM Adaptation Layer number 5, AAL-5This protocol handles bursty data traffic with non-real-time requirements. Internet access for web services or e-mail could be an example of an application.
5.5.3 The Exchange SideThe exchange side has three main components as was described in chapter 3:
High-
Low-
Subscriber side Exchange side
POTS traffic
Broadband trafficADSL
POTS lineinterface (LIC)pass
filter
pass filter
modemHigh-
Low-pass filter
pass filter
ADSL modem
New Functions and Features
63
• The Access Unit for ADSLThis PCB contains the ADSL modems as well as other subscriber unique equipment.
• The FiltersThe role of the filters was to separate the POTS traffic from the broadband traffic. Frequencies below 4 kHz are only sent to the telephone.
• The Exchange Terminals (ETs)The ETs connect the broadband access parts with the broadband core parts. In most cases there is a so called edge router connected to the network to take care of the internet traffic.
There are different variants of the ET board available. Which one selected depends on the traffic demands from the connected subscribers and how the operator has built the access transport network. The variants available are:
• E1, up to 4 x 2.048 Mbit/s links connected to one board.• E3, one 34 Mbit/s line if higher capacity is required. • STM-1, one 155 Mbit/s line based on SDH (please study chapter 5.6 on
page 64).
All broadband units within the subrack are connected to a so called cell-bus. The cell-bus runs in the backplane of the subrack and is a high-speed bus based upon cells similar to ATM. The speed of the bus is about 850 Mbit/s. It is usually the ET board that is “master” on the bus. This means that it is the cell-bus port on this board that determines who should have access to the bus at any given moment.
5.5.4 The Subscriber SideThe subscriber has the little “box” referred to as Network Termination. Inside the NT, you will, among other things, find the following:
• The remote ADSL modem. It is referred to as ATU-R.• A small ATM multiplexer.• An Ethernet interface based upon the 10BaseT interface.• Two ATM-F 25.6 interfaces
5.5.5 Protocols, an ExampleATM is used as it supports different types of services with different demands. In most cases, the ADSL access will be used for Internet access. In that case, an IP protocol is used on top of the ATM protocol AAL-5. The Internet protocol used is PPP, Point-to-Point Protocol, which is intended for use over serial lines, including dial-up telephone connections. Figure 5.9 shows the protocols used over the ADSL access.
AXE Access 910
64
Figure 5.9Example of an Internet connection via the Ethernet interface
5.6 SDH
5.6.1 PDH and SDHPDH, which stands for Plesiochronous Digital Hierarchy, was developed to increase the capacity of digital transmission. However, as the different transmission standards evolved, flexibility was lacking. PDH is:
• bit interleaved which makes it impossible to extract data at higher rates than 2 Mbit/s
• controlled by hardware which makes the multiplexers inflexible.
The different bit rates in PDH can be seen in Figure 5.10.
Figure 5.10Bit rates in PDH
The problems in PDH has to a great extent been solved in SDH, Synchronous Digital Hierarchy. The development of SDH started some 10 years ago and the main characteristics are:
• Not bit interleaved as address information is sent along with the information. This makes it possible to “drop” the information even at high bit rates.
• The multiplexers are software controlled. This means that the operator can configure the network from a remote terminal.
• Developed for higher bit-speeds (Giga bit/s)
Physical layer ADSL
ATM layer
ATM
AAL-5
Internet layer
User NT AU ADSL Router
ADSL
ATMEthernet
PPP
SDH
ATM
AAL-5
PPP
SDH
ATMEthernetor Ethernet
10BaseT 10BaseT
ET
E1E2
E3E4
2.048 Mbit/s8 Mbit/s
34 Mbit/s140 Mbit/s
565 Mbit/s
MUXMUX
MUXMUX
New Functions and Features
65
5.6.2 Bit Rates in SDHThe basic bit rate in SDH is 155 Mbit/s. This bit rate is referred to as STM-1, Synchronous Transport Module-1. Just as in PDH, the bit rates are increased by a factor 4 in several steps. The table below shows the different bit rates, what they are referred to and the number of simultaneous calls on the same optical fibre pair/coaxial cable pair.
For the lowest bit rate, the 155 Mbit/s, it is possible to have electrical format by using a coaxial cable. It is possible to have optical format too. However, for higher bit rates, only optical format will do.
5.6.3 Add/Drop and Terminal MultiplexersIn SDH, there are basically two ways to use the multiplexers. Either as a so called terminal multiplexer (TM) or as a so called add/drop multiplexer (ADM). Figure 5.11 shows the two variants.
Figure 5.11Terminal and add/drop multiplexers in SDH
It is the same hardware that can be used as a terminal or an add/drop multiplexer.
5.6.4 Inside an AXD 155Inside an SDH multiplexer, there is a duplicated switch and interfaces. Figure 5.12 shows the main components inside the multiplexer.
STM-n Bit rate Number of 64 kbit/s calls
STM-1 155 Mbit/s (electrical or optical)
~1900
STM-4 622 Mbit/s (optical) ~7500
STM-16 2500 Mbit/s (optical)
(2.5 Gbit/s)
~30 000
STM-64 10 000 Mbit/s (optical)
(10 Gbit/s)
~120 000
TerminalMultiplexer
Add/DropMultiplexer
SMUX(AXD 155)
SMUX(AXD 155)
AXE Access 910
66
Figure 5.12Blocks inside an AXD 155
5.6.5 Usage of SDH in AXE Access 910The ET board, which is used in the MUA subrack for broadband access, is in fact an SDH multiplexer. This means that the access node can be connected to an electrical or optical ring and configured as an add/drop multiplexer. The future access network will look like the example in Figure 5.13.
Figure 5.13The access transport network when SDH is used
5.7 Operation and Maintenance Functions
5.7.1 Central Trace and DebugThis function makes it possible to perform tracing and debugging in Access Unit software from a centrally located position (for example, an Operation and Maintenance Centre, OMC).
The AUs belong to APT and they are “invisible” to the APZ. This means that the function is an APT function and not, as the Program Test System, an APZ function. The operating system for the AU contains most of the
Interface
Tributary
Switch A
Switch B
East West
Interface
Tributary Tributary
Interface
Interface
BA BA BA
e.g. 2 Mbit/s
AXE Localexchange
Router
SDH opticalring, 155 Mbit/s
New Functions and Features
67
functions, but communication with the AU and presentation of results are made by APT. Examples of trace and debug activities are:
• Display of system and process status• Tracing of operating system signals• Simulation of operating system signal sending• Read and write in the physical memory• Restart control.
It is also possible to connect a portable PC directly to an AU (and TAU for that matter) and perform the same trace and debug activities. Please study Figure 5.14.
Figure 5.14Local and central trace and debug
5.7.2 AU ConfigurationThis function makes it possible to configure the analogue line circuits from the local exchange or from an Operation and Maintenance Centre, OMC. For this, various configuration parameters are sent to the AU board and stored in the processor’s memory. The system downloads the parameters via the TAU. Please study Figure 5.15.
Local trace
LocalExchange
Central traceand debug
and debug
AXE Access 910
68
Figure 5.15Download of configuration parameters to the AU
Examples of parameters that can be downloaded to the AU are:
• Line signalling parameters• Transmission parameters• Semi-permanent connection indicator• Private metering indicator.
5.7.3 Software Upgrade (Local/Central)The software in the AU and in the TAU is stored in a so called FLASH memory which retains it during power off. The contents of the FLASH memory are copied into the primary memory of the AU/TAU processor upon initial start and restart.
The memory of the AU/TAU can be upgraded from the central control system in the local exchange. The reason for such an upgrade could be new functions, correction of software, setting of market-specific parameters etc. There will be two ways to load the software in the AU/TAU:
• One which uses the TAU as the loading platform• One which directly loads the software into the AU/TAU. For this, the
AU/TAU must be blocked and taken out of traffic.
5.8 New EMRP platformOne important part of the AUS is a completely new EMRP platform. In the old SSS5 structure, there was one EMRP, Extension Module Regional Processor, for each LSM (Line Switch Module). In the basic configurations, the LSM connected 128 PSTN subscribers or 64 ISDN-BA subscribers.
In AXE Access 910, the Access Units have a powerful microprocessor executing, among other things, the V5 protocol. In the AUS, there is still need for a processor that takes care of the following functions:
AU
TAU
AU
AU
TAU
AUSETC
GroupSwitch
RPG
CP-A CP-B
AU
New Functions and Features
69
• Regional software for the time switch (TSR), Keyset Code Receivers and tone handling (KRT) and some more functions
• In two of the AUSs: functions for the STR, Signalling Terminal Remote.
The solution is to have a microprocessor powerful enough to replace the old EMRP and the old STR. The chosen processor is based upon Motorola PowerQUICC which contains all functions needed for a standalone processor except for the memory. Figure 5.16 illustrates the general principle of the new EMRP.
Figure 5.16Parts in the new EMRP
The CPU is a 32-bit micro processor running at 25, 40, 50 or 66 MHz and powered by 3.3 V. The FLASH memory will be 6 Mbyte and the RAM memory 16 Mbyte. In most applications there will be 32 HDLC circuits and two V.24 interfaces.
The FLASH memory is used as a local backup and will be used for reloading the RAM memory in case of restarts. If all the software can be stored in the FLASH memory, no CP-EMRP load is needed during the restart. This will shorten the time needed for the restart. The software is compressed in the FLASH memory to save space.
The name of the EMRP is EMRP-T where the T stands for “time switch connected”. The reason for having this name is of course that all buses have been removed and the EMRP is connected to the time switch and uses connections via the time switch to communicate with other units in the system.
In two of the AUS in each access node, there will be functionality for STR, Signalling Terminal Remote. However, the STR function will be implemented in software and be part of the EMRP. When implemented like this, the STR is referred to as STR-T. The software modules of the EMRP can be seen in Figure 5.17.
Supportcircuit
CPU
Clock
Flashmemory
RAMmemory
HDLC I/O, V24
System bus
AXE Access 910
70
Figure 5.17Software modules in the EMRP
The following information shows what the operating system does and how its functions have been divided into smaller parts:
• OS Kernel
− Memory handling, allocation of memory − Process scheduling, determines which process to run− Inter-process communication, handles signals between
processes− System timing, “job table”
• Boot and Basic System
− Cold start, reset and power-on− Load and store program in Flash memory− Compress and decompress programs
• Start and Restart
− Hardware reset− Warm restart of operating system− Warm restart of application
• Memory Management− Physical memory handling− Memory allocation and memory protection
• Real Time Clock• Diagnostic Functions
− Overload protection− Load measurements
ResetBoot
OSE-Delta
STR-T
CSL
EMRP-T
Application
APT:TSRKRTRetc.
EMRPB-T
APZ:EMGFDSEMGFDRTEETR
New Functions and Features
71
5.9 V5 Related Functions
5.9.1 Access Unit V5 ApplicationThe V5 interface is used between the local exchange and the Access Units in the access node. The interface uses V5.1 as each AU is a multiplexer. In the local exchange, the RPG executes the V5 software and the AU processor executes the V5 software in the AU. Figure 5.18 shows the main principle.
Figure 5.18Internal V5 signalling between the RPG in the local exchange and the AUs
The V5.1 signalling uses time slot 16 in the E1 link between the AU and the AUS. From the AUS to the local exchange, any time slot can be used.
5.9.2 External InterfacesExternal V5 signalling means that the local exchange talks to an external unit outside the AXE Access 910, or with a unit other than AXE Access 910. The external V5 signalling could be a radio access system like DRA 1900 or any other type of access node supporting V5.1 or V5.2.
5.9.3 C-channel Concentration, CCCThe C-channel is the V5.1 signalling channel between the AU and the AUS. According to the V5.1 protocol, time slot/channel 16 should be used for this signalling. However, in the AUS, several C-channels can be concentrated to one C-channel (statistically multiplexed). The amount of signalling traffic on one channel, for only 30 subscribers, is not great (particularly not for PSTN). Depending on the traffic, a large number of C-channels may be concentrated in the AUS. Inside the AUS, the HDLC-pool, high level data link control pool, will terminate the V5.1 protocol and multiplex the signalling traffic to one time slot/channel towards the local exchange. Figure 5.19 shows the main principle.
AU
AU
AU
AUAUS
ETC
GroupSwitch
RPG
CP-A CP-B
T. 16
T. 16
V5.1
AXE Access 910
72
Figure 5.19C-channel concentration
The concentration of C-channels is always done on an individual AUS basis. In most cases, the number of AUs connected to one AUS is in the range of 14-15. The number of concentrated C-channels that can be handled per RPG depends on the processor used and the traffic. Each configuration has to be dimensioned individually.
5.9.4 Generic Access Manager, GAMThe Generic Access Manager is not a function that is unique to AXE Access 910 but one can say that it is essential for the AXE Access 910 concept. As the name indicates, it is the function used for many types of accesses. The main aim of GAM is to enable different types of signalling protocols to access a group of RPGs. One group of RPGs handles one type of protocol. Redundant hardware can be defined which means that all channels handled by one RPG, are transferred to another RPG if the original processor becomes faulty. Figure 5.20 illustrates the main principle.
Figure 5.20Example of signalling terminals administrated by GAM
AU
AU
AU
AU
AUS
ETC
GroupSwitch
RPG
CP-A CP-B
T. 16
T. 16
HDLC
ETC
GroupSwitch
RPG
RPG
RPG
RPG
ETC
ETC
ETC
ETC
ETC
V5.1, Executive
V3 (PRA), Executive
V5.1, Stand-by
V3 (PRA), Stand-by
AX
E A
cces
s 91
0
New Functions and Features
73
Note that one single command is needed to arrange signalling from one E1 link. The GAM function will then establish a path through the time switch, allocate an RPG, reserve a channel in the E1 link and then interconnect the two via the group switch.
5.10 Stand Alone Function, SAFThis function existed in the “old” SSS5 and is used in AXE Access 910 with some modifications. The main aim of the function is to allow certain traffic in the access node even if the link to the local exchange is broken. The most important types of calls are those to emergency numbers (112 in most countries in western Europe).
The following points can be made about the SAF function:
• The SAF function can only deliver PSTN calls. ISDN calls are not handled during SAF mode.
• The Mesh network carries all the traffic between the AUSs.• The function will only allow traffic to emergency numbers and no
“normal” traffic between subscribers.• An optional announcing machine can deliver a recorded message
during the period of the restricted traffic.• The HDLC circuits in the AUS terminate the V5.1 signalling and can
send call requests to software inside the AUS.
5.11 Subscriber Line Maintenance FunctionsAll the well proven functions for Subscriber Line Maintenance will be copied from the “old” SSS5 and reused in the AXE Access 910. These functions, which have been developed over a number of years, incorporate a lot of experience. The following functions will be included in AXE Access 910:
• Test calls• Seizure supervision• Howler• External line test• Subscriber-assisted line tests• Repairman-ordered line tests• Line circuit test.
AXE Access 910
74
75
6. Operation
6.1 Chapter IntroductionThis chapter will give you some information about how AXE Access 910 is defined by means of commands. The information is based upon the definition of a node in a test plant and some details may change in the released product. However, most of the new commands and printouts will be found in the chapter. A complete access node is defined by command.
6.2 ConceptsThe OPIs used to operate the AXE Access 910 introduce some new concepts. This chapter describes some of the most important concepts used in OPIs and commands. The concepts are listed in alphabetical order, not in the order of importance.
• AG, Access GroupAll V5 control channels controlled by the same RPG are grouped in a so called access group. In case of reconfigurations due to hardware faults, all control channels are kept together.
• AN, Access NetworkThe term originates from the ETSI standard V5.1 and is defined there as: “a system implemented between the Local Exchange (LE) and user, replacing part or the whole of the local line distribution network.”
• Communication PathSignalling information originating from the V5.1 communication software or from the ISDN subscriber’s D-channel.
• Communication Channel (C-channel)A 64 kbit/s time slot on a V5.1 interface used to carry one or more communication paths.
• CSL, Control Signalling LinkThe duplicated 64 kbit/s signalling link between an STR and an STC.
• CSP, Control Signalling PathA signalling link terminating in an RPG instead of in an STC. At the remote end, the STR is included in the EMRP-T.
After completing this chapter, you will be able to:
• Describe new concepts used in the commands when operating the AXE Access 910
• Define a new access node by means of commands.
Chapter Objectives
AXE Access 910
76
• EM, Extension ModuleUsed to show how AXE can be extended with new hardware.
• EMG, Extension Module GroupThe term used in the “old” SSS to denote a complete group of subscribers connected to the same TSB/STR pair. In AXE Access 910, the term denotes the APZ’s view of the access node. The APT part uses the MACCG. See description of the MACCG.
• GAM, Generic Access ManagerAn AXE function developed to control different types of accesses via controlling channels. GAM is used by AXE Access 910 when connecting V5 C-channels to AXE as well as ISDN-PRA accesses.
• LAPV5, Link Access Protocol for V5Signalling between the AN (access node) and the local exchange follows the standard LAPV5. An LAPV5 frame is the frame format used for all types of signalling information.
• MACCG, Multiple Access GroupThe term used in AXE Access 910 software to denote one complete access node (one EMG). The maximum physical size is two full cabinets with in total 8 subracks.
• Network NodeA concept used to denote an AUS, access unit switch.
• PIU, Plug-In UnitIs a generic name for all types of PCB, printed circuit board.
• V5A set of ETSI standards for connection of access nodes (AN) to the local exchange (LE). The V5.1 supports subscriber multiplexers while the V5.2 standard supports concentrators.
6.3 Definition of Equipment in the Local Exchange
6.3.1 RPG for AU CommunicationThe RPG handling AUs executes the V5.1 protocol software and communicates with the Access Units for both PSTN and ISDN BA. The RPG is defined by the following commands:
• EXRPI, defines the RPG with TYPE=RPG1A.• EXRUI defines the software to be executed and stored in the RPG. In
AXE Access 910, the software blocks RGEXR, RPFDR belong to the APZ and the blocks STAU, DLAU, CTRLAU, MANAU, MHAU, PSTNAU and PSTNHMA will be defined.
• EXEMI defines the EM individuals in the RPG. The block STAU will have 32 devices, one for each V5 channel.
• NTCOI and EXDUI are used to connect the RPG to the group switch.
Figure 6.1 shows a printout of the EMs in the RPG used for Access Unit control.
Operation
77
Figure 6.1Printout of EM in one RPG used for AU control
There can be several concentrated V5 links connected to one and the same RPG. The present number of channels enables all V5 channels to be connected from one MACCG to one RPG if the traffic is less than 0.2 E per subscriber. For higher traffic loads, two RPGs per MACCG will be needed.
6.3.2 RPG for TAU CommunicationAn RPG is also needed for the communication between the local exchange and the TAUs in the MACCG. The definition is the same as for the RPG used for AU communication. However, the command EXRUI and EXEMI will have other parameter values as other software should be stored and executed by the RPG. Figure 6.2 shows a printout from an RPG communicating with a TAU.
Figure 6.2Printout of EM in one RPG used for TAU communication
One RPG can control up to 30 TAUs. The number of TAUs per MACCG differs from customer to customer. If a standard value is used, then 2 TAUs per MACCG will be used and that means that one RPG can handle some 15 MACCGs (one RPG for up to 37000 PSTN subscribers).
EXEMP:RP=82,EM=ALL;
EM DATA
RP TYPE EM EQM TWIN CNTRL PP STATE 82 RPG1A 0 STAU-0&&-31 PRIM WO 82 RPG1A 1 DLAU-0 PRIM WO 82 RPG1A 4 CTRLAU-0 PRIM WO 82 RPG1A 5 PSTNAU-0 PRIM WO 82 RPG1A 6 MANAU-0 PRIM WO 82 RPG1A 7 MHAU-0 PRIM WO 82 RPG1A 10 PSTNHMA-0 PRIM WO
END
EXEMP:RP=80,EM=ALL;
EM DATA
RP TYPE EM EQM TWIN CNTRL PP STATE 80 RPG1A 0 STTAU-0&&-31 PRIM WO 80 RPG1A 1 DLTAU-0 PRIM WO 80 RPG1A 2 MXTAU-0 PRIM WO
END
AXE Access 910
78
6.3.3 RPG for PRA CommunicationISDN PRA, primary rate access, is connected via the Generic Access Manager, GAM, to the RPG in the local exchange. The RPG is defined as shown earlier in this chapter but the software and individuals differ in the two commands EXRUI and EXEMI. Figure 6.3 shows a printout of the RPG used for PRA access.
Figure 6.3Printout of EM in one RPG used for PRA access
The present version of the RPG can control 30 ISDN-PRA accesses.
6.3.4 Definition of STCIn the example studied, the test exchange had “traditional” STCs in the local exchange. This means that they have to be defined by the commands EXRPI and EXEMI. In the near future, most STCs will be implemented in an RPG (referred to as STC-G). Figure 6.4 shows the printout of one of the STCs in the local exchange.
Figure 6.4Printout of EM for the STC
6.3.5 Definition of ETC in the Local ExchangeThe last type of equipment that has to be defined in the local exchange is the ETCs terminating the E1 links from the MACCG. The commands will not be shown here as there are no differences between them and those in the SSS5.
EXEMP:RP=84,EM=ALL;
EM DATA
RP TYPE EM EQM TWIN CNTRL PP STATE 84 RPG1A 0 STPRAE-0&&-31 PRIM WO 84 RPG1A 1 DLPRAE-0 PRIM WO 84 RPG1A 2 MANPRAE-0 PRIM WO 84 RPG1A 3 MHPRAE-0 PRIM WO
END
EXEMP:RP=53,EM=ALL;
EM DATA
RP TYPE EM EQM TWIN CNTRL PP STATE 53 STC2C 1 CLC-4 PRIM WO
END
Operation
79
6.4 Definition of a MACCG
6.4.1 Definition of MACCG and EMGThe first command to use is:
EXEGI:EMG=SWITCH-01,RPA=53,RPB=57,STRTYPE=STRT1A;
This command, which defines the EMG, has not been changed since SSS5. Note again that EMG is an APZ concept and is used to address the access node from APZ functions. The following command defines the MACCG, Multiple ACCess Group:
EXMCI:MACCG=SWITCH-01,EMG=SWITCH-01,VAR=6;
The VAR parameter specifies the number of AUSs in the MACCG. Figure 6.5 shows the printout of the definition made by the commands above.
Figure 6.5Printout of EMG data and MACCG data
6.4.2 Definition of Access Unit Switch, AUSThe AUS is a completely new unit but many commands from the old SSS5 have been reused. The new EMRP-T has to be defined in each AUS but the commands are basically the same as in the old SSS5:
• EXEPI defines the EMs. The parameter TYPE is set to EMRPT1A.• EXEUI is used to define the software that should be loaded into the
EMRP-T. The software identities for this application can be seen in the printout in Figure 6.6.
• EXEEI is used to define the equipment in each EM. The printout in Figure 6.6 shows the names used as well as the software identities (software identities from a test plant with preliminary software are shown).
EXEGP:EMG=SWITCH-01;EMG DATA
EMG TYPE SIDE LINK ST MAST EMGNUMSWITCH-01 REMOTE A CLC-4 WO IDLE 2 REMOTE B CLC-5 WO IDLE 2END
EXMCP;MULTIPPLE ACCESS GROUP CONNECTION DATA
MACCG VAR EMGSWITCH-01 6 SWITCH-01
END
AXE Access 910
80
Figure 6.6Printout of EMG software and equipment data
6.4.3 Definition of Routes and DevicesThe next step is to define the routes and devices needed between the access node and the local exchange. A software route in block CJ, Combined Junctor, should also be defined. There are no major differences, in relation to these definitions, between the AXE Access 910 and the old SSS5.
• EXROI creates a bothway route with DETY=RST.• EXRBC alters route data.• EXDRI connects devices (from block RST) to the route.• NTCOI defines the SNT (Switching Network Terminal)• EXDUI connects the devices to the SNT.
6.4.4 Definition of the Position of AUSWhen the AUS has been defined, its position in the hardware can be defined by command EXPUI. Figure 6.7 shows a printout of the Plug-In Unit’s position.
EXEDP:EMG=SWITCH-01,EM=0;EMGEM SOFTWARE UNIT AND EQUIPMENT DATA
EMGSWITCH-01EM 0SUNAME SUID EQM SUPEIEX1R 9000/CAA 203 01 R1B06 H’0045TEETR 9000/CAA 140 054 R1A03 H’00B2EMGFDR 9000/CAA 140 007 R1A03 H’00ACAUSR 9000/CAA 203 03/3 R2A03 AUS-0 H’0095KRTR 9000/CAA 203 05/5 R2A01 KRT-0 H’0016TSR 9000/CAA 203 04/4 R2A01 TS-0 H’00D1ETR 9000/CAA 203 06/6 R2A01 ETAUS-0 H’00DDSTCONR 9000/CAA 140 178/F9 R1B01 STCON-0 H’00A3SAHR 9000/CAA 140 195 R1A01 SAH-0 H’00C8
END
Operation
81
Figure 6.7Printout of the position of a PIU
6.4.5 Definition of Network NodeNetwork node is a term used to denote the AUS and all the E1 links connected to it. In the old SSS5 and in the first phase of the AXE Access 910 there is no reference to the concept “network node”. It is completely new in AXE Access 910.
The network node is defined with a new group of commands starting with the letters NNxxx.
NNCOI:NODE=AUS-0,VAR=2;
This command defines the network node. The parameter VAR indicates the number of “ports” available in the hardware. A “port” is the same thing as an ET device handling an E1 link.
NNUPI:NODE=AUS-0,PORT=27,DEV=RST-0&&-31;
The command defines the equipment connected to each port. The port, in this case, is used for the E1 link to the local exchange. Figure 6.8 shows a printout of the network node when E1 links to the local exchange have been defined.
EXPUP:PIU=AUS-0;PLUG-IN UNIT DATA
MACCG SR POS PIU STATE BLSTATE STANDBYSWITCH-01 1 1 AUS-0
END
AXE Access 910
82
Figure 6.8Printout of Network Node
6.4.6 Definition of TAUThe TAU, Test, Administration and Maintenance Unit, is responsible for maintenance-related activities in the MACCG. The hardware connections between the TAU and the AUs are via buses between the subracks and also in the backplane of each subrack (LCOM and ACOM). The parameter SR, subrack, has to be used in the command defining the TAU.
The TAU is first of all connected to the AUS by connecting it to the network node:
NNUPI:NODE=AUS-0,PORT=21,DEV=LITAU-0;
The TAU is connected to port number 21 of the AUS and the next action will be to define the DIP, digital path.
DTDII:DIP=0LITAU,NODE=AUS-0,PORT=21;
NNUPP:NODE=AUS-0;NETWORK NODE USER TO PORT CONNECTION DATA
NODE PORT DEV DIP INTCONNAUS-0 0 YES 1 YES 2 YES 3 YES 4 YES 5 YES 6 YES 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 RST-32&&-63 27 RST-0&&-31END
Operation
83
The TAU’s position in the subrack is defined in the next step:
EXPUI:PIU=TAU-0,POS=15,MACCG=SWITCH-01; (?)
It was mentioned earlier in this chapter that a TAU is connected to one or more subracks for controlling the AUs from a maintenance perspective. The command EXTGI is used for this definition.
EXTGI:PIU=TAU-0,SR=0;
The definition of the subracks can be printed by command EXTGP. Please study Figure 6.9.
Figure 6.9Printout of Control Group data (only partly shown)
6.4.7 Definition of Access UnitThe Access Units are defined in a similar way as the TAU. The same commands are used and the parameters are almost the same. The commands below define one AU:
NNUPI:NODE=AU-0,PORT=7,DEV=LIAU-0;
DTDII:NODE=AU-0,PORT=7,DIP=0LIAU;
EXPUI:PIU=AU-0,POS=1,MACCG=SWITCH-01;
The digital link then has to be activated by the command DTIDC.
Figure 6.10 shows how the TAU and three AUs have been connected to the AUS (network node).
EXTGP:MACCG=SWITCH-01,CG=0;TEST MAINTENANCE AND ADMINISTRATION UNIT CONTROL GROUP DATA
MACCG PIU SR PIUSWITCH-01 TAU-0 0 AU-0 AU-1 ... ...END
AXE Access 910
84
Figure 6.10Printout of Network Node
6.4.8 Connection via Generic Access Manager, GAMGAM is a function for connecting several different types of accesses to the same signalling platform, the RPG-based signalling terminals in AXE. By having one common access manager, operation and maintenance is simplified. Each type of access (i.e. protocol) must have a dedicated RPG. This means that the TAU communication and V5 protocols have to be connected to different RPGs.
In GAM, the different applications are handled as different “access groups”. One access group comprises all interfaces connected to the same RPG. To connect the TAU and the AUs to two different RPGs, the commands below have to be used.
GNACI:DIP=0LITAU,AG=4,RPTYPE=RPG;
GNACI:DIP=0LIAU,AG=5,RPTYPE=RPG;
NNUPP:NODE=AUS-0;NETWORK NODE USER TO PORT CONNECTION DATA
NODE PORT DEV DIP INTCONNAUS-0 0 YES 1 YES 2 YES 3 YES 4 YES 5 YES 6 YES 7 LIAU-0 0LIAU 8 LIAU-1 1LIAU 9 LIAU-2 2LIAU 10 LIAU-3 3LIAU 11 12 13 14 15 16 17 18 19 20 21 LITAU-0 0LITAU 22 23 24 25 26 RST-32&&-63 27 RST-0&&-31END
Operation
85
When the command is executed, GAM defines a path from the DIP in the command to an RPG belonging to the access group. The access group is created when the first interface is connected to it. By defining the same access group number, it is possible to connect more interfaces to the same access group. Figure 6.11 illustrates the general principle.
Figure 6.11GAM reserves a path between the DIP and the RPG
Figure 6.12 shows a printout of the two access groups to the TAU and to the AUs.
Figure 6.12Printout of Generic Access Manager data
6.4.9 Connection of AU to V5The Access Units are still not connected to the V5.1 interface. The command EXPCI will connect each port on the AU to a specific, fixed, time slot in the V5.1 interface. Interface number 0 will be connected to time slot 1, and the process continued until all the 30 interfaces have been given a time slot. As usual, time slots 0 and 16 are excluded as they are used for synchronization and V5.1 signalling.
AU
AU
AU
AUSETC
GroupSwitch
RPG
CP-A CP-B
AU
T.16AG
DIP
GNACP:AG=4;GENERIC ACCESS MANAGER CONNECTION DATA
AG ORDERAG APPTYPE RPTYPE DEV DIP TS CONCG4 4 RPG 0LITAU 16END
GNACP:AG=5;GENERIC ACCESS MANAGER CONNECTION DATA
AG ORDERAG APPTYPE RPTYPE DEV DIP TS CONCG5 5 RPG 0LIAU 16 1LIAU 16END
AXE Access 910
86
EXPCI:PIU=AU-0,DIP=0LIAU,DEV=LIMA-0&&-29;
EXPCI:PIU=AU-1,DIP=1LIAU,DEV=LIBAMA-0&&-14;
The first command connected a PSTN access unit and the latter one an access unit for ISDN basic rate access.
6.4.10 Deblocking All the defined equipment has to be deblocked before service can start. The new deblocking commands are:
NNBLE:NODE=AUS-0;
The command deblocks a network node (an AUS).
BLPUE:PIU=AU-0;
The command deblocks a Plug-In Unit (PIU) of type AU or TAU.
6.4.11 Connection of SubscribersThere are no new or modified commands used to connect subscribers to the system. As an example, the SULII command is still used to connect an ordinary PSTN subscriber:
SULII:SNB=1234567,DEV=LIMA-0;
For ISDN subscribers, the commands IUDCI, IUANI and IUAPC are still used.
6.4.12 Connection of Primary Rate AccessPrimary rate access, PRA, is connected in a very similar way as AU and TAU. The commands are the same but some parameters differ:
NNUPI:NODE=AUS-0,PORT=18,DEV=LIPRAM-0&&-31;
This command connects the PRA to the network node AUS-0 at port number 18 (the ET device number 18).
DTDII:NODE=AUS-0,PORT=18,DIP=0LIPRAM;
This command defines the DIP, digital path, between the AUS and the PABX.
GNACI:DEV=LIPRAM-16,AG=6,RPTYPE=RPG;
Figure 6.13 shows the printout of the GAM connection data.
Figure 6.13Printout of Generic Access Manager data for Primary Rate Access
GNACP:AG=6;GENERIC ACCESS MANAGER CONNECTION DATA
AG ORDERAG APPTYPE RPTYPE DEV DIP TS CONCG6 2 RPG LIPRAM-16 END
87
7. Maintenance
7.1 Chapter IntroductionMaintenance will change a lot when the new AXE Access 910 is introduced. The repair procedures will not change much but the maintenance efforts should be substantially lower with AXE Access 910 than with the existing SSS5.
7.2 Maintenance PrinciplesMuch effort has been put into improving the overall system characteristics. Any system replacing an older version must be better than its predecessor. There are many different parts that have been modified to make the system characteristics superior.
7.2.1 More Robust DesignThe AXE Access 910 has much less cabling than the SSS5 as more functions are put on single boards. Cables have connectors at each end, and these give problems when they get dirty or when they start to oxidize. By reducing the number of cables in the switch, these risks are reduced.
7.2.2 Different Communications Paths for Traffic and MaintenanceThanks to the TAU, the traffic and maintenance functions do not have to use the same communication channel between the local exchange and the access node. Figure 7.1 illustrates the main principle.
After completing this chapter, you will be able to:
• Describe the fundamental maintenance principles used in AXE Access 910
• Understand how the maintenance principles affect the total system characteristics.
Chapter Objectives
AXE Access 910
88
Figure 7.1Separate communication channels for traffic and maintenance
Because of this principle, the probability that both communication paths might be faulty, is extremely low. It also means that future maintenance functions can use the maintenance path without interfering with the traffic in the V5.1 interface. Similarly, new traffic functions do not have to interfere with the maintenance traffic.
7.2.3 Same Functions for Subscriber Line MaintenanceEricsson has a very long tradition of inventing, designing and implementing maintenance functions in its telecommunication systems. The functions for Subscriber Line Maintenance (SLM) have all been developed over a great number of years for AXE Access 910’s predecessor, the SSS5, and could be considered “state of the art”. For this reason we have retained the same SLM functions in the AXE Access 910.
7.2.4 Less HardwareEach circuit and component has a certain probability of becoming faulty. By reducing the number of components in a system, you also reduce the total risk of having faults stopping your system. Less hardware means less faults in the hardware. Simple enough...
7.2.5 Maintenance of Broadband FunctionsThe narrowband access units in AXE Access 910 are all managed and maintained by AXE. For the broadband parts (e.g. ADSL), there is a separate management system inherited from ANx-DSL. The system is referred to as “ANxMS”, ANx Management System.
Another difference is that most maintenance function for the broadband part rely on the maintenance protocol SNMP, simple network management protocol, defined by IETF, internet engineering task force. The SNMP protocol is the main standard protocol in the computer and data communications industry.
AU
TAU
AU
AU
TAU
AUS
ETC
GroupSwitch
RPG
CP-A CP-B
AU
ETC RPG
64 kbit/s formaintenance
n x V5.1 for traffic
38 kbit/s formaintenance
Maintenance
89
7.3 Equipment Protection SwitchingBy having any of the optional function “AUS protection switching” or “AU protection switching”, the maintenance cost for the system is reduced dramatically. Here are some figures related to a node with 2000 subscribers:
• Faults affecting the traffic is improved by a factor of 6.• Faults affecting more than one line board is reduced by a factor of 20
from one occurrence every 16 years to once every 320 years.• The line Down Time is improved from 5 down to 0.35 minutes.
AXE Access 910
90
91
8. Future Functions
8.1 Chapter IntroductionAXE Access 910 is not just a new access node. It is the start of a new access node platform that will be used for many types of narrowband and broadband applications. This chapter gives some information about future plans regarding hardware and IP/ATM integration. Please note that this information is rather preliminary and that plans may change due to products launched by competitors or for other reasons that are not under Ericsson’s control. The development plans are still not detailed enough to specify when different applications are available.
8.2 Compatible HardwareThe hardware in AXE Access 910 is based upon BYB 501 which is fully adapted to broadband applications. For example, all subracks are like sealed metal boxes which give them good EMC characteristics. This is important when high frequencies are handled by the boards.
Our customers benefit from having hardware that is fully adapted to broadband. They can buy a future-proof system which can be expanded with broadband applications as they become available. This hardware allows the operator to freely mix narrowband and broadband accesses. By using a standard 19-inch building practice, it is easy to integrate 3:rd party products or datacom products in the building practice. For example, a router or an ATM switch can easily be co-located in the same cabinet if there is free space.
AXE Access 910 will in the future use further decreased hardware. With the introduction of the AUS, the “system on board” was started. Next step will be to have “systems on chip” meaning that an ASIC contains all the functions of a system, for example the AUS.
After completing this chapter, you will be able to:
• Describe the advantage of having a remotely controlled MDF
• Describe how AXE Access 910 can be upgraded in the future to meet new demands.
Chapter Objectives
AXE Access 910
92
8.3 Remotely Controlled MDFA Main Distribution Frame, MDF, is a connection field which terminates external cabling and, using jumpers, allows interconnection to internal cabling. The external cabling is designed to operate in the outside environment while the internal cabling is more simple regarding insulation. The MDF connects one subscriber line to one Line Interface Circuit (LIC). As the MDF is a static connection field, someone has to go out to the site and move the cable if a subscriber wishes to change service. For example, if a subscriber, connected to a LIC delivering POTS, wishes to have ISDN BA, the subscriber’s line has to be physically moved to another position.
The remotely controlled MDF solves this problem by having a switch in the MDF. The switch is analogue and built up by means of relays. This switch makes it possible for the operator to remotely connect the subscribers to other LICs that provide new services. The switch is referred to as MXC, mechanical cross connect.
The advantages of the remotely controlled MDF are many:
• The operator can provide a new access service in a few minutes instead of within hours or days.
• The operator can increase revenue by having a faster connection to new services.
• The operator can decrease the operation costs significantly by avoiding staff going to the access node each time a subscriber wishes to change service.
Figure 8.1 illustrates the main principle.
Figure 8.1Remotely controlled MDF
POTSRemotely Controlled MDF
ISDN-BA
HDSL
ADSL
Customer Care Centre
Future Functions
93
An alternative to the MXC is to combine the LIC for POTS with the ADSL modem on the same board. This reduces the need for changing hardware position in the MDF as the combined line board itself creates the switch-over (from POTS to ADSL).
8.4 Integration of IP and ATMBoth Internet Protocol (IP) and Asynchronous Transfer Mode (ATM) are important components in the future network that will carry both voice and data. AXE Access 910 has a migration strategy towards future broadband solutions.
8.4.1 Voice over DSLThere is a possibility to have a derived voice channel carried by the DSL transmission system. This will give a digital speech communication end-to-end with higher quality. There are several alternatives discussed within different standardisation bodies. AXE Access 910 will support this service once standardisation is settled.
8.4.2 Voice over ATMVoice over ATM is a planned addition to the Access 910 product family.
8.4.3 Integration of IPIP can be carried by ATM in a highly efficient way. ATM will give the IP traffic “carrier class” and real-time problems in IP are taken care of by ATM. This means that AXE Access 910 already from the beginning has the possibility to carry IP traffic.
AXE Access 910
94
95
9. Index
19 inch rack 23AAAL, ATM adaptation layer 62Access Network Handler, ANH 50access unit for ADSL 39access unit for ISDN BA 38Access Unit Switch, AUS 50access unit switch, AUS 12access unit, AU 11access unit, definition of 83ACOM 34, 37ADM, add/drop multiplexer 65ADM, add/drop multiplexers 9ADSL 60ADSL Lite 60AG, access group 75ALB30 13ALTAU, external alarm handler (function block) 53AN, access network 75ANxMS, ANx management system 88attenuation of speech samples 15AU (ISDN), access unit for ISDN-BA 38AU (PSTN), access unit for PSTN 36AU configuration 67AU processor 36AUBA, access unit basic access (function block) 47AUCORD, co-ordination of AU protection switching (function block) 53AUMAN, access unit management (function block) 53AUPSTN, access unit PSTN (function block) 46AUS control system 16AUS Network 12AUS, access unit switch 14AUS-C, AUS Connection board 40AUSCORD, co-ordination of AUS protection switching (function block) 53AUV5, Access Unit V5 Application 44AXE hardware inventory management 55BBBMAN, broadband manager (function block) 52BYB 101 23BYB 202 23BYB 501 23Ccabinet in BYB 501 24
AXE Access 910
96
cabling in BYB 501 26C-channel 71central trace and debug 66CG, control group 75Clock in AUS 15command
BLPUE 86DTDII 82EXDRI 80EXDUI 80EXEDP 80EXEGI 79EXEGP 79EXEPI 79EXEUI 79EXMCI 79EXMCP 79EXPCI 86EXPUI 80, 83EXPUP 81EXRBC 80EXROI 80EXTGI 83EXTGP 83GNACI 84GNACI, PRA access 86GNACP 85NNBLE 86NNCOI 81NNUPI 81, 82NNUPI, PRA access 86NNUPP 82, 84NTCOI 80SULII 86
communication channel 75connection field, CCF 34cooling principles 25CPRM, central private metering (function block) 46CSFSK, code sender FSK signalling (function block) 49CSKD, code sender, digital (function block) 49CSL, control signalling link 75CSP, control signalling path 75CSR-D, code sender/receiver digital (function block) 49CTRLA, control access unit (function block) 47CTRLAU, control access unit (function block) 46CTRLLED, control of LED in MACCG (function block) 53DD-channel 39definition of RPG 76Digital Path Access Unit Switch, DIPAUS 50Digital Path Supervision and Test, DIPST 50distribution unit, DU-2 28DLAU, data link layer V5 (function block) 46, 47DLTAU, digital line TAU (function block) 52DMT, discrete multitone 61DTMF, tones 16Eelectromagnetic compatibility (EMC) 27
Index
97
EM, extension module 76EMG, extension module group 76EMRP ring 16EMRP-T 69Exchange Terminal Interface, ETDIF 51external alarms 56FFCMAN, function change multiple access handler (function block) 53filter for ADSL 40FLASH memory 68Flash memory 37footprint 20function blocks 43GG.703 16G.704 16G.706 16GAM 72GAM, generic access manager 76GAM, generic access manager (function block) 46Hhardware identification 55HDLC pool 16HDSL 59IICS, internal communication service 19ISDN PRA connection 14ISP, in service performance 21KKey-set code Receiver and Tone sending, KRT 51LLAPV5, link access protocol for V5 76LCOM 34LE, local exchange 75LIAU, line interface access unit (function block) 48LIBAV5, line interface basic rate access, V5 (function block) 48LIC, line interface circuit (ISDN-BA) 38LIC30 13local exchange 18MMAADMC, MACCG administration (function block) 52MACCG, multiple access group 76MAOAM, Multiple Access, Operation, Administration and Maintenance 44MAUS, Multiple Access Unit Switch 44MAUS, multiple access unit switch 49measurements, performed by TAU 41mechanical key 29mesh network 17MUA, Multiple Access Subrack 32multimeter instrument, in TAU 42
AXE Access 910
98
Multiple Access Unit Switch, set of parts 49MUS, Multiple Access Unit Switch 30NNBA, Narrowband Access Subrack 31NNADMC, network node administration (function block) 53NT, network terminal 36NT, Network Termination (for ADSL) 61PPDH, plesiochronous digital hierarchy 64PIU, plug-in unit 76power consumption 21power distribution 28PowerQUICC (processor used in EMRP-T) 69protection switching 57protection switching of AU 58protection switching of AUS 57PSHWCTL, protection switching hardware control (function block) 53PSTN, PSTN protocol handler (function block) 46QQSLAC, quad subscriber line audio processing circuit 36RRAM memory 37RAM, random access memory 37reception of DTMF 15Remote Stage Traffic, RST 51RPG, definition of 76SSAF function 73SDH, synchronous digital hierarchy 64set of parts 43Signalling to EMRP software in AUS 19signalling to ISDN-PRA 19signalling to TAU 19SIS, Single Switch Subrack 33SLIC 13SLIC, subscriber line interface circuit 36SLM, subscriber line maintenance 88SNMP, simple network management protocol 88Software upgrade of AU and TAU 68STM-1, synchronous transport module-1 65STR-T 69subrack in BYB 501 24switching of speech samples 15TTAU board 41TAU, definition of 82TAU, test, maintenance and administration unit 18TAU-C board 42TAUCMAN, TAU-C manager (function block) 52TAUMAN, TAU manager (function block) 53
Index
99
test access bus 35test, maintenance and administration unit, TAU 11time switch 15Time Switch Maintenance, TSMT 51Time Switch, TS 51TM, terminal multiplexer (SDH) 65transmission of tones 15two-step high-ohmic distribution (TS-HOD) 28VV.24/V.28 16V5 71, 76V5.1 10V5.2 10visual fault indication 56
AXE Access 910
100
EN/LZT xxx xxx RPA4© Ericsson T elecom AB
Ericsson T elecom ABInterna l T ra iningM V/ERA/G D P/K FS-126 25 Stock holm , Sw edenT elephone: +46 8 719 9222http://w w w .m v.etx.ericsson.se Su
bjec
t to
alte
ratio
ns w
ithou
t pri
or n
otic
e. P
rinte
d in
Sw
eden
.