Abstract:
As networks become a part of our lives, we are becoming dependent on them,
and thus we need them to be highly dependable.
Dependability is an important requirement in network's design and operation.
This thesis introduces and investigates the topic of dependability modeling for
networks. It concentrates on dependability attributes models, which should be
set for the network. The results of dependability modeling and analysis, if
properly considered, will directly improve the network performance, and guide
the future design decisions. This fact requires that dependability modeling and
analysis should form an integral part of the network design, operation, and
development stages.
Since all required information for dependability modeling and planning has to
be gathered, the conversion of network system information into dependability
models can be set. This thesis shows how this can be done. A different
modeling techniques are used to describe the models of the main dependability
attributes, reliability, availability and maintainability, which should be done in
order to achieve high dependability network (HDN).
Dependable network design and modeling is too demanding today since,
however a general assumption has been conducted that the network being
constructed is free of failures and will run as intended, but without
dependability modeling it is just a hope.
The major goal of the thesis is to ensure the importance of network
dependability modeling as an integral part of the network design, operation,
and modifications and to provide hints for network system improvement by
applying these introduced models to reach which is called nowadays the five
nines, or 99,999% for reliability and availability of a network.The three main attributes of dependability (reliability, availability, and
maintainability) are modeled for the network to achieve the acceptable level of
dependability.
The Sudan university network (SUST WAN) was taken as a case study in
which the dependability main models were set and the network reliability and
availability were measured together with the recommendations to increase the
reliability and availability values for this network.
Since the PSTN forms an essential part in SUST network, methods to find the
reliability and availability for the PSTN are described.
For any operational networks the three models (reliability, availability, and
maintainability) are the more appropriate models for the network performance
evaluation, and they provide useful guides for network's redesign and also to
make the required modifications to the current network design to increase its
dependability.
