BS EN 61907:2010 pdf download

BS EN 61907:2010 pdf download.Communication network dependability engineering.
5.1.3.2 Network failure classification
Most network failures can be classified as to their probable causes so that failure analysis results can be categorized for network dependability improvement.
• Facilvty-related network failure — This is related to failures of individual network elements whosn failure rate data can be used for predicting the corresponding node and link dependability parameters.
• Traflic-related network failure — This is related to the operation scenarios of network service traffic, which changes according to the network users’ usage demands. Network design should consider users usage demands and plan network traffic capacity to satisfy most operation scenarios to avoid network service performance degradation.
• Disaster-related network failure — This is related to failures that are man-made or caused by natural disaster. Sometimes the network facilities in the disaster area may be totally destroyed.
• Security-related network failure — This is related to network failures caused by insufficient security to prevent unauthorized intrusion, such as hacking, cyber attacks or sabotage activities.
• Scheduled, activity-relaled network failure — This is related to failures that occur during scheduled network maintenance activities, such as software upgrade causing the network to be temporarily out-of-service
• Human factor-related network failure —This is related to failures due to human error. misused or negligence, such as network design errors, configuration errors, or mistakes in management of software versions.
5.1.3.3 Network fault conditions
A network failure represents an event in network operation and maintenance where the occurrence of an anomaly or malfunction in performance is experienced. A fault condition related to the failure occurrence describes the fault state or status of the fault condition observed. In practice, the cause of actual network failures is often unknown at its initial observation of incident reporting. The Incident report captures the observed symptoms of the fault state or fault conditions on the network’s inability to perform its function. The complexity of the network operations, the involvements of diverse service functions, and the time limitation to restore network services often prevent further investigation of the failure event situation. Priority under such fault conditions is to reroute, reboot and recover the failed service functions in order to restore normal network services. Network incident reporting should capture the failure symptom in order to initiate appropriate follow-up action and determine the cause of failure where practicable. Relevant information, captured by incident reporting during network operation and maintenance, provides an important source of failure data for implementing an effective network fault management system
5.1.3.4 Network fault management system
The network fault management system is a network service support system, It facilitates the reporting of failure event data and capturing the observed fault conditions to support management and correction of network faults, The fault management system consists of a set of supporting functions to detect, isolate and also compensate, where applicable, environmental changes as well as correct network malfunctions, The system is designed and deployed to support network service restoration for tracing and identifying faults, performing diagnostics tests, correcting faults, activating alarms and reporting error conditions. maintaining error logs and providing error detection notifications (see 51.5.3). Network fault management system is an essential enabling mechanism to support network service functions.
5.1.4 Establishment of network dependability requirements
5.1.4.1 Network d.p.ndablllty requirements Identification
Information gathering helps identify market needs of the new or upgraded network. The objective is to determine the commercial and technical requirements for network development and service enhancement, Information can come from various sources.
a) Information on upgrading an old network — Network design could use the existing network as a basis for upgrade or enhancement, Such as expansion of existing service facilities and capability to meet growing market needs. This would avoid extensive resource Investments on building a completely new network. The enhancement incorporates new functional features and provides additional services and capacities to augment and complement the old network service functions.
b) Service functions and performance information — These are the network service functions required by the network service provider; they include existing applications (e.g. telephone service) and new applications (e.g. Internet service), as well as requirements for network performance, capacity and other network service features.
C) Customized information — This type of information covers, for example, the requirements of end.users for customized services provided by the communication network. For example, users may ask for a videophone service.