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What do you mean by telecommunication network? Give its

architecture.A telecommunications network is a collection of terminals, links and nodes which connect to

enable telecommunication between users of the terminals. Each terminal in the network have a

unique address so messages or connections can be routed to the correct recipients. The collectionof addresses in the network is called the address space.

The links connect the nodes together and are themselves built upon an underlying transmission

network which physically pushes the message across the link, using circuit switched, message

switched or packet switched routing.

Components of telecommunication network:

All telecommunication networks are made up of five basic components that are present in each

network environment regardless of type or use. These basic components include terminals,

telecommunications processors, telecommunications channels, computers, and

telecommunications control software.

• Terminals are the starting and stopping points in any telecommunication network 

environment. Any input or output device that is used to transmit or receive data can be

classified as a terminal component.

• Telecommunications processors support data transmission and reception between

terminals and computers by providing a variety of control and support functions. (i.e. convert

data from digital to analog and back)

• Telecommunications channels are the way by which data is transmitted and received.

Telecommunication channels are created through a variety of media of which the most

 popular include copper wires and coaxial cables (structured cabling). Fiber-optic cables are

increasingly used to bring faster and more robust connections to businesses and homes.• In a telecommunication environment computers are connected through media to perform

their communication assignments.

• Telecommunications control software is present on all networked computers and is

responsible for controlling network activities and functionality.

Early networks were built without computers, but late in the 20th century their switching

centers were computerized or the networks replaced with computer networks.

In general, every telecommunications network conceptually consists of three parts, or planes:

• The control plane carries control information (also known as signaling).

• The data plane or user plane or bearer plane carries the network's users traffic.

• The management plane carries the operations and administration traffic required

for network management.

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 Network tree diagram

Traditionally, the Public Switched Telephone Network (PSTN) has been the dominant type of 

 public telecommunication network worldwide, and consists of telephone lines, fibre optic cables,

microwave transmission links, communication satellites and undersea telephone cables.

The advent of cellular technologies led to the interconnection of the mobile phone (cellular)networks with PSTN. The PSTN was based on circuit-switched technology, which had been

 primarily developed for voice traffic. Technologies developed for data transmission like PSDN,

ISDN, Dial-up, DSL and others also leverage the existing PSTN infrastructure.

Due to the growing demand for data and video services and the limitations of the circuit-

switched technology, telecom operators find it economically prohibitive to expand their circuit-

switched networks tomeet demand. This has led to a gradual move towards the adoption of 

 packet-based switching technology. Newer 2G and 3G mobile phone systems like GPRS, EDGE

and HSPA that are designed for data transmissions are also based on packet-based switching

technology.

The term, Next Generation Network (NGN), is generally used to refer to these packet-based

networks that transport all information and services – data, voice and media like videos. NGNs

are most commonly based on the Internet Protocol (IP). NGN is expected to reshape the current

structure of the telecommunication system and access to the Internet

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Today’s telecom networks are a combination of several technologies – PSTN, 2G, 3G – that

have evolved over a period of time. Generally speaking, the current telecom network comprises

the following parts:

Access Network  – This is the part of the network that connects the telecommunication

equipment – fixed or mobile – to the core network for provision of services. This includes the

local loop (telephone cables/fibre optic) of the fixed networks and the radio links in a mobile

network, the radio towers, base stations and controllers.

Core Network  – This consists of the network elements responsible for service delivery and

setting up of the end-to-end connection and handovers, and may be classified into circuit-

switched and packet-switched domains. The core network includes components such as switches,

the Mobile Switching Centre (MSC), the Host Location Register (HLR), the Visitor Location

Register, and the Authentication Centre.

Application and Management Network  – This consists of end-user application servers, and

systems and services that support the operation, administration and maintenance functions of the

network.Internal Network – This is the telecom operator’s internal network. This includes systems used

 by the operator’s employees.

External Network  – This is the externally visible network, typically deployed in the De-

Militarized Zone (DMZ). This includes the Web servers, application servers and mail servers

that are hosted by the telecom operator.

Telecommunication network architecture

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Structure of Management Information ModelManaged objects are abstractions of data processing and data communication resources for the

 purpose of management... The design of systems management requires that an approach be

adopted that will allow the specifications to be standardized in a modular fashion and provide the

extensibility of the protocol and procedures. The information model makes use of object-orienteddesign principles because they provide the above capabilities and provide for reuse of pieces of 

specification.

Managed objects are defined for the purpose of managing systems. Each managed system may

contain a Management Information Base (MIB). In the MIB, managed objects are used to

represent the resources that may be managed within the system. A MIB is the conceptual

repository of the management information within an open system. It represents the resources in a

managed system that has been externalized for communication with a managing system. They

are externalized in the sense that a managing system has knowledge of the MIB, not of the actual

data structures of the managed system's internal database; and the two may be vastly different.

Resources that are not managed do not need managed object representations. By managing thisMIB, a managing system can control the managed system's actual resources. This control

includes the ability to retrieve information about the resources and to provision, reconfigure, or 

inhibit the capabilities of the resources within managed system.

A managed object is an abstraction of a physical or logical entity for the purpose of 

management. It contains the specific information associated with the management of that

 physical or logical entity.

A managed object class defines the characteristics of a type of physical or logical resource.

Instances of a managed object class exist to represent specific instances of a resource. Therefore,

a managed object is an instance of a managed object class.

 Management Information System of an Organization

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 Management Information Model 

Structure of TMN Information ModelThe term TMN is introduced by the ITU-T (the former CCITT) as an abbreviation for 

‘Telecommunications Management Network’. The concept of a TMN is defined by

Recommendation M.3010. TMN has a strong relationship with OSI management, and defines anumber of concepts that have relevance for Internet Management.

According to M.3010, “a TMN is conceptually a separate network that interfaces a

telecommunications network at several different points”. The relationship between a TMN and

the telecommunication network that is managed, is shown in Figure 1. According to this figure,

the interface points between the TMN and the telecommunication network are formed by

Exchanges and Transmission systems. For the purpose of management, these Exchanges

and Transmission systems are connected via a Data Communication Network to one or more

Operations Systems. The Operations Systems perform most of the management functions;

these functions may be carried out by human operators but also automatically. It is possible

that a single management function will be performed by multiple Operations Systems. In thiscase, the Data Communication Network is used to exchange management information between

the Operation Systems. The Data Communication Network is also used to connect Work 

Stations, which allow operators to interpret management information. Work Stations have man-

machine interfaces, the definition of such interfaces fall outside the scope of TMN (Work 

Stations are therefore drawn at the border of the TMN).

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 Physical Architecture

 Next to a functional architecture, TMN also defines a physical architecture. The latter 

architecture shows how TMN’s functions, which were defined by the functional architecture, can

 be implemented into physical equipment. TMN’s physical architecture is thus defined at a lower 

abstraction level than TMN’s functional architecture. The physical architecture shows how

function blocks should be mapped upon building blocks (physical equipment) and reference

 points upon interfaces. In fact, the physical architecture defines how function blocks and

reference points can be implemented.

 Functional Vs Physical Architecture

 Logical Layered Architecture

TMN recognizes that, corresponding to human society, a hierarchy of management

responsibilities exist. Such hierarchies can be described in terms of management layers; the

architecture that describes this layering is called the Logical Layered Architecture. To deal with

the complexity of management, the management functionality with its associated information

can be decomposed into a number of logical layers. A usual decomposition of management

functionality leads to the following layers of abstraction:

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• Element management layer.

• Network management layer.

• Service management layer.

• Business management layer.

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TMN Management LayersA usual decomposition of management functionality leads to the following layers of abstraction:

• Element management layer.

• Network management layer.

• Service management layer.• Business management layer.

 Element management layer 

The functions of individual Network Elements are managed by Operations Systems Functions

(OSF) in the Element Management layer. This layer deals with vendor specific management

functions and hides these functions from the layer above, the Network Management layer.

 Examples of functions performed at the Element Management layer are:

• Detection of equipment errors,

• Measuring power consumption,

• Measuring the temperature of equipment,

• Measuring the resources that are being used, like CPU-time, buffer space, queue length etc.,• Logging of statistical data,

• Updating firmware

 Network Management layer 

Whereas the responsibility of the Element Management layer is to manage NEFs implemented

within single pieces of equipment, the responsibility of the Network Management layer is to

manage the functions related to the interaction between multiple pieces of equipment. At

network management level the internal structure of the network elements is not visible; this

implies that buffer space within routers, the temperature of switches etc. can not be directly

managed at this level.

 Examples of functions performed at this layer are:

• creation of the complete network view,

• creation of dedicated paths through the network to support the QoS demands of end users,

• modification of routing tables,

• monitoring of link utilization,

• optimizing network performance, and

• detection of faults.

The OSFs at the Network Management layer use the vendor independent management

information that is provided by the OSFs in the Element Management layer. In this interaction

the OSFs at the Network Management layer act in a manager role and the OSFs in the ElementManagement layer in an agent role.

 Service Management layer 

The Service Management layer is concerned with management of those aspects that may directly

 be observed by the users of the telecommunication network. These users may be end users

(customers) but also other service providers (administrations). Service Management builds upon

the management information that is provided by the Network Management layer, but does not

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‘see’ the internal structure of the network. Routers, switches, links etc. can therefore not directly

 be managed at Service Management level.

 Examples of functions performed at the Service Management layer are:

• Quality of Service management (delay, loss, etc.)

• Accounting

• Addition and removal of users

• Address assignment

• Maintenance of group addresses.

The notion of Service Management can be regarded as the most valuable contribution of TMN

and other management frameworks, most notably the Internet management framework, may

take advantage of this idea and extend their management frameworks with this notion.

 Business Management layer 

The Business Management layer is responsible for the management of the whole enterprise.

This layer has a broad scope; communications management is just a part of it. Business

management can be seen as goal setting, rather than goal achieving. For this reason businessManagement can better be related to strategical and tactical management, instead of operational

management, like the other management layers of TMN.

 Functional hierarchy

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Management servicingThe four basic management functions: planning, organizing, leading and controlling.

 Planning:

 Definition: The function of management of systematically making decisions about the goals to

 be achieved and activities or actions needed to achieve those goals that an individual, a group, awork unit, or the overall organization will pursue in the future. Plans are developed for the entire

organizational unit and individuals for certain period of time.

Its activities include:

• Analyzing current situations.

• Anticipating the future.

• Determining the organizational objectives.

• Deciding the activities to be involved.

• Choosing strategies.

•Determining resources to achieve organizational goals.

Organizing:

 Definition: “The management function of assembling and coordinating human, financial,

 physical, information and other resources needed to achieve organizational goals.”

Its activities include:

• Specifying job responsibilities.

• Grouping jobs into work units.

• Resource allocation.

 Leading:

 Definition: The management function that involves the manager's efforts to stimulate high performance by employees and includes directing, motivating and communicating with

employees, individually and in groups.

Its activities include:

• Directing the workforce.

• Motivating your subordinates.

• Communicating with employees.

Controlling:

 Definition: The function of management of monitoring progress and making needed changes to

make sure that the organizational goals are achieved.Its activities include:

• Setting performance standards that indicate progress toward long-term goals.

• Monitoring staff performance through performance data evaluation.

• Identifying performance problems by comparing performance data against

standards and take corrective actions.

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TMN MANAGEMENT FUNCTIONThe TMN management function is associated with management functionality in a managed

system. It may be triggered by internal events of the managed system (for example, report alarm)

or invoke by the managing system. They are usually grouped into five functional areas:

1. Performance management2. Fault (Maintenance) management

3. Configuration management

4. Accounting management

5. Security management

Performance management  includes all activities necessary to maintain the short term

customer view of quality of service. It gathers statistical data for monitoring and controlling the

effectiveness and behaviours of the network, NE or equipment.

1.  Performance monitoring (PM)

PM involves the collection of data relating the performance of the NE. It is designed to

measure the overall quality using monitored parameters and also to detect characteristic pattern before the quality of signal drops below an acceptable level.

1. The Common function

 NE sends current PM data to TMN on its request. It may be generated

 periodically by the NE and sent to TMN whenever it demands or by parameter 

threshold triggering. TMN directs the NE to start/stop the collection and to reset

storage registers for PM data.

2. Performance controlling (PC)

1. The Common function

TMN makes NE to set up a schedule for reporting of PM data, to send the PM

data report schedule and to assign designated values to PM attributes. NE sends

current PM attributes to TMN on its request. In addition, TMN directs NE to

change or to set the PM parameter threshold, also to set up a schedule for the

execution of QoS test calls and sends the current QoS call schedule to TMN. NE

reports the result of QoS test calls to TMN whenever it demands or on a schedule

 basis. Beside that, TMN asks NE to change or to set the attributes of QoS test

calls, to start/stop sending test calls and sends the current QoS test call attributes.

Fault (Maintenance) Management includes all procedure necessary to handle

system alarm, correct and test falling equipment, and respond intelligently to customerscomplaints.

1.  Alarm

TMN is able to monitor NE failures in near real time. Indication is made by the NE when

a failure occurs. TMN determines the nature and severity of the fault basing on the

indication. It may determine the effect of the fault on the services supported by the fault

equipment in two ways. The first one is that a data base within a TMN may interpret

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 binary alarm indication from the NE, which requires little of the NE beyond self-

monitoring capability. The second is that it may transmit self- explanatory messages to a

TMN if the NE has sufficient intelligence, but requires additional support of message

syntax for the description of fault condition from both NE and TMN.

2. Correction

Automatic restoration report from NE to TMN indicates a specific line, service,

equipment or system that has been switched as part of NE's protection procedures.

TMN requests NE to start/stop hot-standby procedures for system or service so as to let a

redundant unit to take over with minimum disruption to traffic.

Reload procedure involves a request from TMN to NE for reconstruction of a service or a

system from a particular dump record. A reload report is the reporting of a reloaded

service or system from a dump, from NE to TMN.

3. Testing 

It can be done in two ways. The first way is that a TMN orders a NE to carry out analysis

of circuit or equipment characteristics, which is done entirely within the NE. Results arereported to the TMN automatically and immediately or on a delayed basis. Another way

is that the analysis is done within the TMN. It asks the NE to provide access to the circuit

or equipment concerned and no more messages are exchanged with the NE.

Configuration Management covers activities such as installing

equipment, provisioning equipment, behaviours of network and modifying parameter.

It provides functions for control over, identify, collect data from and provide data to NEs.

1.  Provisioning 

It consists of procedures need to bring an equipment into service, excluding installation.

When the unit is in service, supporting programs will be initialised with the TMN. Status

of the unit, for example, whether in service or not, may be controlled by provisioningfunctions.

Use of provisioning functions differs in different NEs. Frequent use of these functions is

required in digital switching and cross-connect equipment as circuits are put up and

dropped. While only one usage is usually required in small transmission elements.

2.  Status and control of NE 

TMN provides monitoring and controlling over the NE on request. A status check is

usually provided in conjunction with each control function so as to check that the

resulting action has taken place. These functions are corrective when dealing with faulty

conditions.

Status and control functions form part of routine maintenance which is done on a periodic

or automatic basis. TMN will stop the operation of a faulty equipment and may rearrange

equipment or re-route traffic. It can also enable entering of proposed configuration to

analyse the feasibility of the design before its implementation.

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 Accounting Management includes the measurement and control of costs and customers billing.

It provides a function set which enable the use of the network service to be measured and

determine the cost of it. It also collects the accounting record and

1.  Billing 

Some NEs is used to determine charges to customer accounts and it will send to the OS

within TMN if it requires these data. To enable the maintaining of the record of billing,

this type of function needs highly efficient and redundant data transport. Processing must

 be carried out in near real time for large number of customers.

•  Security Management is responsible for controlling access to customers, network data

and resources.

It is concerned not with the provision and use of encryption or authentication techniques

themselves but rather with their management, including reports concerning attempts to

 breach system security. There are two important function, first one is managing the

security and maintaining security audits. The other one is performing the network 

management task in a secure way.

COMMON MANAGEMENT FUNCTIONS

The common management functions are called system management functions. The following

system management functions are still in the standardizing process or have been completed:

• Accounting meter management

• Alarm report

• Event report

• Logging

• Measurement summarization

• Object management

• Objects and attributes for access control

• Relationships management

• Security alarm reporting

• Security audit trail

• State management

• Test management

• Workload monitoring