OSS History / Standards

I like the dreams of the future better than the history of the past.”
Thomas Jefferson.

Operational Support Systems (OSS) is a term used to describe the information processing systems that assist an Organisation to manage their communications networks. These tools allow an organisation to coordinate resources, processes and activities to design, build, operate and maintain communications networks.

From the early days of telecommunications carriers (the companies that offered telecommunications services such as telephony), these activities were performed manually. With the advent of computers, carriers began to harness their processing power by developing applications to help them operate their vast networks.

These initial applications had a narrow range of functionality. However, disparate functional units within the carriers soon sought to improve efficiency by sharing data and leveraged multiple systems by integrating them. For example, a customer would place an order and their details would be stored in one system. The designers would then record the customer’s specific design configuration in another system and then this design would be implemented into the telephone exchange itself. In this case, the automatic sharing of information between systems is known as flow-through provisioning but requires significant integration effort.

1.1        TMN (Telecommunications Management Network)

In the early days OSS integration tended to require bespoke solutions. Efforts to bring a level of standardisation to OSS integration resulted in the ITU-T developing the TMN (Telecommunications Management Network) series of standards in 1988. These standards identified the following four layers of functionality

TMN Framework
Image sourced from here.

The framework identifies four logical layers of network management:

Business Management Layer (BML) – represents the functionality relating to strategic business planning such as trending, quality, etc and provides the basis for billing, budgeting and goal-setting.

Service Management Layer (SML) – is responsible for defining the services offered by the carriers. This provides the interface between a customer’s services and the network including definition, administration and charging.

Network Management Layer (NML)  – provides the overall management view of the network as a sum of component parts. This is particularly necessary for representation of end-to-end concepts such as circuits that traverse multiple element management domains. Is responsible for the end-to-end supervision, configuration and control of the network.

Element Management Layer (EML) – provides definition and coordination of a collection of network devices, albeit a sub-set of the entire network. This layer would normally include consolidation of alarm management, backup, logging, and maintenance of the systems that support the network devices.

A fifth layer, Network Element Layer (NEL) – Represents the network devices themselves that the customers’s services traverse.

It should be noted that there are no strict boundaries to these levels of abstraction, meaning that each vendor’s product position within the management system continuum can be blurred and resultant terminology can be confusing. In Common Terminologies we provide a discussion on the terminology that is commonly used in the industry and help the reader to better understand the ways that these terms are used in the context of PassionateAboutOSS.com.

Management Functional Areas presented in Recommendation M.3400 include:

1) Customer Administration;

2) Network Provisioning Management;

3) Work Force Management;

4) Tariff, Charging and Accounting Administration;

5) Quality of Service and Network Performance Administration;

6) Traffic Measurement and Analysis Administration;

7) Traffic Management;

8) Routing and Digit Analysis Administration;

9) Maintenance Management;

10) Security Administration;

11) Logistics Management.


1.2        FCAPS Model

Further extension of TMN model occurred when ITU-T incorporated ISO’s FCAPS (Fault, Configuration, Accounting, Performance and Security) model into their recommendation on Management Functions (M.3400).

Fault management – Aims to identify, isolate, remedy and log negative events that occur within a network. Fault logging can be extended to include trend analysis as a means of predicting errors or abnormal behaviour on the network. Network devices are able to propagate faults to higher network management layers that then provide advanced functionality such as root cause analysis. Fault severity analysis can be used to prioritise fault remediation activities.

Configuration management – Aims to store the attributes (or configurations) of network devices allowing the tracking of network resources and changes in the network. Pushing changes to the network, also known as provisioning, allows configuration updates such as the creation of circuits or paths through various network devices. Tracking of status allows an operator to plan for future designs and network build-out.

Accounting management – Aims to gather statistics for users such that billing characteristics and usage quotas can be managed. RADIUS and TACACS are commonly used protocols for accounting management. In some cases, the A in FCAPS represents Administration, the management of authorised network users, permissions and operational activities

Performance management – Aims to gather statistics that determine the level of efficiency that the network is operating at. The actual statistics, or counters, recorded can vary widely between network device types, determined by the specific performance analysis needs of the device. Counters can include throughput, signal strength, resource utilisation, error rates, latency, etc. These performance statistics can also be used to analyse capacity or reliability trending. By establishing threshold analysis of counters, such as failure rates, operators can be alerted to imminent fault conditions or establishment of load balancing measures to alleviate underperformance of the network before the issues become service affecting.

Security management – aims to control access to network assets, securing against unauthorised access.

1.3        Telecommunication Management Forum (TM Forum)

Evolution of the networks under management and sophistication of the services offered across them lead to the establishment of TM Forum‘s New Generation Operations Systems and Software (NGOSS) program. Rapidly evolving business models have necessitated more agile evolution of OSS tools.

Through collaboration by numerous service providers and equipment manufacturers, TM Forum models have gained widespread use in the field of OSS implementations. The main reference models proposed are:

  • An application model (the Telecom Applications Map or TAM) – aims to provide a framework of telecommunications applications, extending to the definition of which telecommunications functionality should appear within each application construct
    TAM Map
  • A process model (the enhanced Telecom Operation Map, or eTOM) – aims provide a common language and catalogue of business processes used in telecommunications environments. This level of standardisation aims to simplify the lines of communication between service providers and associated systems integrators
    eTOM Level 0 Map
  • An information model (the Shared Information / Data model, or SID) – aims to define the essential entities, relationships and attributes of data objects prevalent in telecommunications applications / databases. It also provides a common language for use by OSS developers / integrators. TMF has also sought to develop standardised SID-based APIs (Application Programming Interfaces) such as OSS/J to expedite integration of disparate systems
  • A system integration framework (the Technology Neutral Architecture, or TNA) – aims to provide architectural standardisation, whilst remaining technology neutral, including common interfaces, mechanisms and policies


1.4        ITIL

Just as there has been an increasing overlap between IT (Information Technology) and telecommunications network technologies, there has also been an increased prevalence of IT frameworks (such as ITIL) being used alongside telecommunications frameworks (such as NGOSS’s eTOM). Telecommunications service providers are reliant on highly reliable IT infrastructure (eg servers, etc) and ITIL is currently seen as best-practice for the management of these types of assets. Similarly, customers are outsourcing the management of end-to-end IT and telecommunications infrastructure, making demands on their service providers to supply high quality service management of the customer’s increasingly critical network and IT assets.

ITIL (IT Information Library) was developed by the UK Government in an attempt to standardise IT processes, particularly the handover from implementation to ongoing IT support environments. ITIL is commonly used within service providers’ back-end frameworks, but also has relevance when customers stipulate ITIL frameworks as part of the managed services contracts they let out to service providers.

The short video below provides some additional insights into ITIL. Please note that I have no affiliations with the producers of this video.

As indicated in the previous section, eTOM was developed by the TMF to guide the development and management of fundamental business processes within a generic telecommunications service provider. It shares some commonalities and differences with ITIL.

ITIL Framework
This image has been sourced from here

TMF has published an eTOM – ITIL Application Note (GB921L) entitled Using eTOM to model the ITIL Processes. This application note provides guidance on the modelling of IT Service Management using the standard process elements within eTOM. It also shows the detailed overlay of ITIL processes with eTOM Level 2 processes.

Rough ITIL to eTOM mapping
The description of the rough ITIL to eTOM mapping above can be found here.

1.5        Standards Compliance

Whilst vendors may claim to be compliant to each of the standards above, most of the above-mentioned “standards” are simply recommendations that can be adhered to in an ad-hoc manner by vendors. The one exception is the TM Forum, which provides thorough testing of a vendor’s product against NGOSS principles. A list of products that are certified to be compliant with NGOSS can be found on the TM Forum website (www.tmforum.org).

The TM Forum also offers Frameworx Implementation Conformance Assessment, which provides verification of a service provider’s internal business processes and data model.

1.6 Registration Authorities

The IEEE acts as the registration authority for many of the unique identifiers used in telecommunications networks. IEEE maintains a number of different identifiers including the OIDs used by SNMP. Tutorials for these registers can be found here.

1.7 Additional Information

Is there something else specific that you need to find an answer for?

  • The book, “Mastering your OSS” contains a more in-depth history on OSS as well as hundreds of facts, stories, tips and tricks relating to Operational Support Systems
  • The freebies page. which provides
    • Additional background research material like terminology, etc
    • Templates / tools that we use on the projects we contribute to
    • Implementation techniques that we also use on our projects
    • A list of hundreds of OSS vendors
  • The market research report, “The Changing Landscape of OSS” provides a deep-dive analysis of the nascent technologies that are impacting, and impacted by, OSS. The report also provides research into the organisations that are investing in each of these technologies from an OSS perspective
  • The Passionate About OSS blog has thousands of posts, which will hopefully cover your area of interest
  • If you still can’t find what you’re looking for, contact us here because we are Passionate About OSS and would be delighted to assist you

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