There are several network management methodologies or models that incorporate network maintenance activities. It is important to understand that these models are guidelines not standards. Standards can be defined as industry-recognized best practices, frameworks, and agreed-upon principles or concepts and designs, which are designed to implement, achieve, and maintain the required levels of processes and procedures. Guidelines, on the other hand, are simply recommended actions and operational guides for users. Unlike standards, which are mandatory, guidelines are simply used as reference material. Common network management models, which are described in the following section, include the following:
- Telecommunications Management Network
- Information Technology Infrastructure Library
- Cisco Lifecycle Services
Telecommunications Management Network (TMN)
The Telecommunications Management Network (TMN) framework is a model defined by ITU-T for managing open systems in a communications network. It is referenced in ITU-T Recommendation M.3010. It is important to understand that the TMN was developed to provide a framework for service providers to manage their service delivery network; however, the same basic concepts can also be applied to standard enterprise networks. This framework defined four management architectures at different levels of abstraction:
- A functional architecture
- An information architecture
- A physical architecture
- A logical layered architecture
NOTE: While delving into the specifics on these various architectures is beyond the scope of the TSHOOT certification exam, the following section provides a brief description of each.
The functional architecture describes various management functions. Next, the information architecture describes concepts that have been adopted from OSI management. The physical architecture which defines how these management functions may be implemented into physical equipment, and finally, the logical layered architecture includes a model that shows how management can be structured according to different responsibilities.
Within the logical layer, the framework also provided a common methodology and logic that is applicable to the management of private enterprise networks by introducing another four abstract layers of management functionality. These additional four layers of abstraction are:
- The Business Management Layer
- The Service Management Layer
- The Network Management Layer
- The Element Management Layer
NOTE: Again, while delving into detail on these layers is beyond the scope of the TSHOOT certification exam, the following section provides a brief description of each.
The Business Management Layer (BML) has a broad scope which includes responsibility for the management of the whole enterprise. This layer is more aligned with strategic management, rather than day-to-day operational management.
The Service Management Layer (SML) 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). Examples of functions that are performed at the Service Management Layer include administration, accounting, the addition and removal of users, and QoS management. The BML and SML provide the link between IT and the business.
The Network Management Layer (NML) deals with fault and performance data for the network as well as overall network management and configuration, which includes tasks such as network monitoring and fault detection, optimization, and configuration changes, for example. It is important to understand that this layer pertains to the overall network. Individual device management is covered at the Element Management Layer (EML).
The Element Management Layer deals with configuration management, fault, and performance at the device level. This layer deals with vendor specific management functions and hides these functions from the layer above, the Network Management layer. Examples of the functions that are performed at this layer include alarm management, handling of information, backup, logging, and maintenance of hardware and software, and measuring resource utilization, e.g. CPU, memory, and power consumption.
An Overview of Network Management Models – FCAPS
FCAPS is the International Organization for Standardization (ISO) TMN model and framework for network management. The acronym FCAPS stands for Fault management, Configuration management, Accounting management, Performance management, and Security management. These are the network management categories used by the ISO. The following sections describe the five functional areas in the FCAPS model.
Fault management is a life cycle centered that revolves around identifying problems through continuous monitoring of the entire network, correlating the fault data, and isolating the problem to the source. The overall fault management life cycle includes the following tasks:
- Fault and problem detection
- Handling and acknowledging alarms sent by devices
- Fault and problem isolation using a filtration and correlation process
- Fault correction and recovery
- Tracking problems through resolution via a trouble ticketing system
Configuration management encompasses the management of actual device configurations, the configuration change control process, which may include the commissioning and decommissioning of network devices, backing up and restoring configurations, and overall workflow management for the administrators performing the configuration changes. Another important aspect is the ability to track and log changes to device configurations.
Accounting management covers methods to track usage statistics and costs associated with time and services provided with devices and other network resources. Accounting information, such as link utilization and device resource utilization can also be used for Service Level Agreement (SLA) purposes ensuring that an agreed-upon level is service is being provided.
Performance management covers the tracking of system and network statistics using a Network Management System (NMS). The data that is collected may include link utilization, errors, response times and availability information. This data can then be used to improve performance for critical traffic, such as Voice over IP (VoIP) for example, by implementing or adjusting Quality of Service (QoS) solutions to make the most efficient use of limited bandwidth. Additionally, performance management monitoring can also be used to establish thresholds and identify network trends, all of which provide valuable data for capacity planning.
Security management addresses access rights that include authentication and authorization, data privacy, and auditing security violations. From a network administration perspective, security management is primarily concerned with controlling access to network devices using, for example, the AAA (Authentication, Authorization, and Accounting) security architecture. However, security management may also include integrating firewalls and other security devices, such as an Intrusion Prevention System (IPS) into the network to protect against viruses, worms, and other malicious types of traffic.
Information Technology Infrastructure Library (ITIL)
Information Technology Infrastructure Library (ITIL) is a set of best practices for Information Technology Service Management (ITSM), IT development and IT operations. The names ITIL and IT Infrastructure Library are registered trademarks of the United Kingdom’s Office of Government Commerce (OGC). ITIL provides businesses with a customizable framework of best practices that can be used to ensure and achieve quality service as well as to overcome some of the difficulties that are associated with the growth of IT systems.
ITIL is organized into a set of texts which are defined by related functions. ITILv3, which is the current (latest) version, defines five processes that cover the entire life cycle of an IT project, from starting its architectural planning, spanning through the design and implementation phases, and covering the operational phases to a continued loop with the services optimization. The five processes or sets defined in ITILv3 are:
- Service Strategy
- Service Design
- Service Transition
- Service Operation
- Continual Service Improvement
Service strategy is both the center and origin point of the ITIL Service Lifecycle. Service strategy focuses on the strategic approach to IT Service Management. The purpose of Service Strategy is to develop the organizational ability to think and act in a strategic manner and transform IT Service Management into a strategic asset. This includes consideration on the services that should be offered, who those services should be offered to, how service performance will be measured, and how the customer and stakeholders will perceive and measure the value of the services, amongst other considerations.
Service Design is part of the overall business change process and is primarily concerned with the design of new or changed services for introduction into the live environment. This includes their architectures, processes, policies and documentation. In essence Service Design simply translates the strategic objectives into portfolios of service and assets. Service Design covers the following life cycle management aspects:
- Service Level Management (SLM)
- Service Level Agreements (SLAs)
- Operational Level Agreements (OLAs),
- Service Improvement Plan
- Service Quality Plan
- Capacity Management
- Availability Management
- IT Service Continuity Management
- Supplier Management
- Compliance Management
- IT Architecture Management
- Risk Management
Service Transition relates to the delivery of services required by a business into operational use.
Service transition includes the following list of processes and activities:
- Service Asset and Configuration Management
- Service Validation and Testing
- Release Management
- Change Management
- Knowledge Management
Service Operation is the stage in the ITIL core lifecycle whose primary purpose is to deliver and support IT services at agreed-upon levels, and to manage the applications, technology, and infrastructure that support the delivery of the services. Service operation entails the delivery of these services to both users and customers and includes the following processes:
- Event Management
- Incident Management
- Problem Management
- Request Fulfillment
- Access Management
Continual Service Improvement (CSI) is an activity that is part of everyday life in IT services. It is not an emergency project that is initiated when someone in authority yells that the network service or performance is sub-par or poor. Instead, CSI is an ongoing way of life that entails continually reviewing, analysing and improving service management processes and the service which allows you to address changes in business requirements, refresh technology cycles, and ensure that high quality is maintained.
Cisco Lifecycle Services (PPDIOO)
The Cisco PPDIOO model encompasses all steps from network vision to optimization, which enables Cisco to provide a broader portfolio of support and end-to-end solutions to its customers. This Cisco life cycle model includes the stages of prepare, plan, design, implement, operate, and optimize; hence the acronym the PPDIOO model.
Within the PPDIOO model, the prepare phase deals with network discovery to understand the business needs, high-level requirements, and any potential challenges. At the end of this stage, a conceptual architecture of the proposed network solution is then presented.
The plan phase of the Cisco PPDIOO model compares the existing network with the proposed network, i.e. the proposed solution in the prepare phase, to help identify tasks, responsibilities, milestones, and resources required to implement the design.
The design phase of the Cisco PPDIOO model articulates the detailed design requirements. In this phase a low-level design, which will eventually be implemented, is designed. Considerations during this phase should also include how to meet requirements for the applications, support, backup, and recovery.
The PPDIOO implement phase addresses the integration of new equipment into the existing network environment based on the design requirements. Supporting implementation documentation, e.g. an implementation and back-out plan, is also presented during this phase.
The operate phase begins after the new device(s) have been implemented or integrated into the existing network. This phase of the PPDIOO model entails the day-to-day network operation, while responding to any issues that arise.
And finally, the last phase of the PPDIOO model, the optimize phase continually gathers the feedback from the operate phase to potentially make adjustments to the existing network, which typically results in another project beginning with the prepare phase. The entire process is then repeated again. During the optimize phase, feedback received from the operate phase may also be used to address any ongoing network performance and support issues.