INTERNATIONAL  TELECOMMUNICATION  UNION

		     ITU-T RECOMMENDATION SUMMARY


Rec. No. : E.862

Title : Dependability planning of telecommunication networks

Study Group : II - Network Operation

Version : Revised

Date of adoption : 1992

Notes :	


Recommendation E.862 is concerned with models and methods for 
dependability planning, operation and maintenance of 
telecommunication networks, and the application of these methods to 
the various services in the international network.

Dependability planning may be accomplished by using essentially two 
different methods.

Intuitive method

The level of dependability is determined by making a synthesis of 
objectives and procedures presently used. It is a pragmatic method in 
absence of an analytical method or in the case when necessary data 
for a thorough analysis is not available.

This method reflects the present status, but is inconsistent in 
achieving what Administrations actually want to attain: 

the most economic level of dependability taking into account customer 
needs and inconvenience.

Analytical method

The analytical method is based on principles defining the object of 
dependability planning. The principles are realized through a 
quantitative model. The level of dependability is deduced by applying 
the model, taking into account all relevant factors in each planning 
case.

-	Basic principle - The main object of dependability planning is 
to find a balance between the customers’ needs for dependability and 
their demand for low costs.

-	Model - Fault consequences are expressed in terms of money and 
are included as additional cost factors in planning and 
cost-optimization. The cost factor reflects the customers’ experience 
of faults in the network, quantified in terms of money, as well as the 
Administration’s costs for lost traffic revenue and corrective 
maintenance.

-	Application - The Administration is provided with a method to 
integrate dependability as a natural part of planning, taking local 
information from the actual planning case into account. This method 
enables the preparation of simplified planning rules.



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