Network element

Last updated

In computer networks, a network element is a manageable logical entity uniting one or more physical devices. This allows distributed devices to be managed in a unified way using one management system.

Contents

According to the Telecommunications Act of 1996, the term 'network element' refers to a facility or to equipment used in the provision of a telecommunications service. This term also refers to features, functions, and capabilities that are provided by means of such facility or equipment. This includes items such as subscriber numbers, databases, signaling systems, and information that is sufficient for billing and collection. Alternatively, it's also included if it's used in the transmission, routing, or other provision of a telecommunications service.

Background

With development of distributed networks, network management had become an annoyance for administration staff. It was hard to manage each device separately even if they were of the same vendor. Configuration overhead as well as misconfiguration possibility were quite high. A provisioning process for a basic service required complex configurations of numerous devices. It was also hard to store all network devices and connections in a plain list. Network structuring approach was a natural solution.

Examples

With structuring and grouping, it is very well seen that in any distributed network there are devices performing one complex function. At that, those devices can be placed in different location. A telephone exchange is the most typical example of such a distributed group of devices. It typically contains subscriber line units, line trunk units, switching matrix, CPU and remote hubs. A basic telephone service leans on all those units, so it is convenient for an engineer to manage a telephone exchange as one complex entity encompassing all those units inside.

Another good example of a network element is a computer cluster. A cluster can occupy a lot of space and may not fit one datacenter. For enterprise solutions, it is common to locate cluster nodes in different locations, even in different regions (settlements).

Maintenance

In general, an NE can generate two types of maintenance information:

  1. Information related to the quality or health of the transmission signal, and
  2. Information related todata its own internal hardware/software integrity.

The functional components of surveillance are performance monitoring and alarm/status monitoring, also known as alarm surveillance. In the national and international standards area for telecommunications operations, performance monitoring and alarm surveillance are classified as subcategories of the more general system management functional categories of performance management and fault management, respectively. Maintenance consists of both preventive and corrective procedures that are designed to (a) prevent troubles and identify potential troubles before they affect service, and (b) detect a network failure that impacts performance and make the appropriate repairs. A typical seven-step maintenance process consists of:

  1. Trouble Detection – Detect trouble by continuous monitoring, periodic tests, per-call or other pre-action tests, or other automatic processes.
  2. Trouble Notification – Send notification of a specific event or condition to a local display or Operations System (OS). Trouble notifications include output messages and visual and audible alarms.
  3. Service Recovery – Minimize the degradation of service by automatic or manual protection actions.
  4. Trouble Verification – Determine whether the reported condition still exists.
  5. Trouble Isolation – Isolate the trouble to its source, preferably to a single field-repairable element, e.g., circuit pack.
  6. Repair – Fix or replace the faulty element.
  7. Repair Verification and Return to Service – Verify that the trouble has been fixed and return the element to service.

Telcordia GR-474 establishes trouble-detecting and reporting criteria for signal transmission failures and internal hardware or software anomalies. GR-474 provides proposed generic requirements that pertain to the Fault and Performance Management functions in transport and switching NEs used for alarm surveillance and control. [1]

GR-474 complements recent criteria in industry standards such as ITU-T Recommendation M.3100, G.707, and G.709, and ANSI T1.

State models

A network element state model facilitates cross domain network management and promotes a multi-vendor environment. The standard definitions and mappings allow Operations Systems to gather state information from NEs and integrate it into a consistent representation of the status of the entire managed network and each of the services that it supports.

Telcordia GR-1093 discusses the two primary state models in industry. [2] One is the Telcordia State Model, which consolidates the state models previously described in several Telcordia documents. By consolidating the models, changes and expansions to the models can be presented and can evolve in a coordinated fashion. Also, inconsistencies and redundancy may be averted. The other model is the International Organization for Standardization (ISO) State Model, which is defined in ITU-T Recommendation X.731. [3]

The state of an entity represents the current condition of availability of the underlying resource or service in the NE from the point of view of management. In the context of the Telcordia State Model, the term "entity" represents an entry in a TL1 administrative view (i.e., represents the resource or service generally identified by the Access Identifier [AID] parameter). In the context of the ISO State Model, the term "entity" means "managed object".

Different types of entities (such as hardware, transport facilities, and subscriber service) have a variety of state characteristics that express the availability of their underlying resources that are specific to each entity type. However, a state model is expected to be common to a large number of types of entities. It expresses key aspects of their availability at any given time. The purpose of the state model is to indicate the availability of an entity in providing its functions and, if an entity is not available, to indicate the cause of the unavailability and what kind of activity may be taken by the manager (e.g., the OS or the craft) to make the entity available.

In a specific application, only a subset of the state model may be needed. The rationale of such restrictions is not described in GR-1093. The technology or application-specific requirements document should be consulted for this information.

The standard definitions and mappings allow Operations Systems to gather state information from NEs and integrate it into a consistent representation of the status of the entire managed network and each of the services that it supports.

To help ensure interoperability, particularly for an OS that interfaces with multiple NEs using one of the two state models, a mapping between the models may be needed. GR-1093 provides a mapping for the two models and also defines the extension to the OSI state/status attributes that is necessary to meet the telecommunications needs of the service providers.

Telecommunications Management Network

A concept of the network element as a distributed entity is widely used in TMN model which in turn is used as a standard for developing element management systems.

See also

Related Research Articles

<span class="mw-page-title-main">OSI model</span> Model of communication of seven abstraction layers

The Open Systems Interconnection (OSI) model is a reference model from the International Organization for Standardization (ISO) that "provides a common basis for the coordination of standards development for the purpose of systems interconnection." In the OSI reference model, the communications between systems are split into seven different abstraction layers: Physical, Data Link, Network, Transport, Session, Presentation, and Application.

<span class="mw-page-title-main">Synchronous optical networking</span> Standardized protocol

Synchronous Optical Networking (SONET) and Synchronous Digital Hierarchy (SDH) are standardized protocols that transfer multiple digital bit streams synchronously over optical fiber using lasers or highly coherent light from light-emitting diodes (LEDs). At low transmission rates data can also be transferred via an electrical interface. The method was developed to replace the plesiochronous digital hierarchy (PDH) system for transporting large amounts of telephone calls and data traffic over the same fiber without the problems of synchronization.

In network management, fault management is the set of functions that detect, isolate, and correct malfunctions in a telecommunications network, compensate for environmental changes, and include maintaining and examining error logs, accepting and acting on error detection notifications, tracing and identifying faults, carrying out sequences of diagnostics tests, correcting faults, reporting error conditions, and localizing and tracing faults by examining and manipulating database information.

The Intelligent Network (IN) is the standard network architecture specified in the ITU-T Q.1200 series recommendations. It is intended for fixed as well as mobile telecom networks. It allows operators to differentiate themselves by providing value-added services in addition to the standard telecom services such as PSTN, ISDN on fixed networks, and GSM services on mobile phones or other mobile devices.

<span class="mw-page-title-main">Network interface device</span> Device that separates the carriers wiring from the customers

In telecommunications, a network interface device is a device that serves as the demarcation point between the carrier's local loop and the customer's premises wiring. Outdoor telephone NIDs also provide the subscriber with access to the station wiring and serve as a convenient test point for verification of loop integrity and of the subscriber's inside wiring.

Simple Network Management Protocol (SNMP) is an Internet Standard protocol for collecting and organizing information about managed devices on IP networks and for modifying that information to change device behavior. Devices that typically support SNMP include cable modems, routers, switches, servers, workstations, printers, and more.

FCAPS is the ISO Telecommunications Management Network model and framework for network management. FCAPS is an acronym for fault, configuration, accounting, performance, security, the management categories into which the ISO model defines network management tasks. In non-billing organizations accounting is sometimes replaced with administration.

Transaction Language 1 (TL1) is a widely used management protocol in telecommunications. It is a cross-vendor, cross-technology man-machine language, and is widely used to manage optical (SONET) and broadband access infrastructure in North America. TL1 is used in the input and output messages that pass between Operations Support Systems (OSSs) and Network Elements (NEs). Operations domains such as surveillance, memory administration, and access and testing define and use TL1 messages to accomplish specific functions between the OS and the NE. TL1 is defined in Telcordia Technologies Generic Requirements document GR-831-CORE.

The Common Management Information Protocol (CMIP) is the OSI specified network management protocol.

Element management is concerned with managing network elements on the network element management layer (NEL) of the TMN . An element management system (EMS) manages one or more of a specific type of telecommunications network elements (NE).

The Telecommunications Management Network is a protocol model defined by ITU-T for managing open systems in a communications network. It is part of the ITU-T Recommendation series M.3000 and is based on the OSI management specifications in ITU-T Recommendation series X.700.

In computing, Web-Based Enterprise Management (WBEM) comprises a set of systems-management technologies developed to unify the management of distributed computing environments. The WBEM initiative, initially sponsored in 1996 by BMC Software, Cisco Systems, Compaq Computer, Intel, and Microsoft, is now widely adopted. WBEM is based on Internet standards and Distributed Management Task Force (DMTF) open standards:

Web Services Resource Framework (WSRF) is a family of OASIS-published specifications for web services. Major contributors include the Globus Alliance and IBM.

Many services running on modern digital telecommunications networks require accurate synchronization for correct operation. For example, if telephone exchanges are not synchronized, then bit slips will occur and degrade performance. Telecommunication networks rely on the use of highly accurate primary reference clocks which are distributed network-wide using synchronization links and synchronization supply units.

Machine to machine (M2M) is direct communication between devices using any communications channel, including wired and wireless. Machine to machine communication can include industrial instrumentation, enabling a sensor or meter to communicate the information it records to application software that can use it. Such communication was originally accomplished by having a remote network of machines relay information back to a central hub for analysis, which would then be rerouted into a system like a personal computer.

OpenSAF is an open-source service-orchestration system for automating computer application deployment, scaling, and management. OpenSAF is consistent with, and expands upon, Service Availability Forum (SAF) and SCOPE Alliance standards.

The Hardware Platform Interface (HPI) is an open specification that defines an application programming interface (API) for platform management of computer systems. The API supports tasks including reading temperature or voltage sensors built into a processor, configuring hardware registers, accessing system inventory information like model numbers and serial numbers, and performing more complex activities, such as upgrading system firmware or diagnosing system failures.

An element management system (EMS) consists of systems and applications for managing network elements (NE) on the network element-management layer (NEL) of the Telecommunications Management Network (TMN) model.

The Application Interface Specification (AIS) is a collection of open specifications that define the application programming interfaces (APIs) for high-availability application computer software. It is developed and published by the Service Availability Forum and made freely available. Besides reducing the complexity of high-availability applications and shortening development time, the specifications intended to ease the portability of applications between different middleware implementations and to admit third party developers to a field that was highly proprietary in the past.

Operations support systems (OSS), operational support systems in British usage, or Operation System (OpS) in NTT, are computer systems used by telecommunications service providers to manage their networks. They support management functions such as network inventory, service provisioning, network configuration and fault management.

References

This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.