With the emergence of advanced integrated services networks, the need for effective
performance analysis techniques has become extremely important. Further
advancements in these networks can only be possible if the practical performance
issues of the existing networks are clearly understood. This thesis is concerned with
the design and development of a measurement system which has been implemented on
a large experimental network.
The measurement system is based on dedicated traffic generators which have been
designed and implemented on the Project Unison network. The Unison project is a
multisite networking experiment for conducting research into the interconnection and
interworking of local area network based multi-media application systems. The traffic
generators were first developed for the Cambridge Ring based Unison network. Once
their usefulness and effectiveness was proven, high performance traffic generators
using transputer technology were built for the Cambridge Fast Ring based Unison
network. The measurement system is capable of measuring the conventional
performance parameters such as throughput and packet delay, and is able to
characterise the operational performance of network bridging components under
various loading conditions. In particular, the measurement system has been used in a
'measure and tune' fashion in order to improve the performance of a complex bridging
Accurate measurement of packet delay in wide area networks is a recognised problem.
The problem is associated with the synchronisation of the clocks between the distant
machines. A chronological timestamping technique has been introduced in which the
clocks are synchronised using a broadcast synchronisation technique. Rugby time
clock receivers have been interfaced to each generator for the purpose of
In order to design network applications, an accurate knowledge of the expected
network performance under different loading conditions is essential. Using the
measurement system, this has been achieved by examining the network characteristics
at the network/user interface. Also, the generators are capable of emulating a variety
of application traffic which can be injected into the network along with the traffic
from real applications, thus enabling user oriented performance parameters to be
evaluated in a mixed traffic environment.
A number of performance measurement experiments have been conducted using the
measurement system. Experimental results obtained from the Unison network serve to
emphasise the power and effectiveness of the measurement methodology.
A Doctoral Thesis. Submitted in partial fulfilment of the requirements for the award of Doctor of Philosophy of Loughborough University.