Side_1_360

Performance requirements and traffic character-
istics are important input parameters for the
design of new network components and con-
cepts. Vendors perform tests of single compo-
nents (router, switch, etc.). Testbeds must also
be established to perform large-scale tests of e.g.
new network mechanisms and network architec-
tures. Such testbeds have no traffic load so a
realistic traffic load must be generated. There is
also a need for accurate traffic measurements to
derive performance measures. [Heegaard] pre-
sents such a distributed test environment for IP
networks.

Finally, measurement data is important as input
to researchers to increase the understanding of IP
networks and develop better solutions. Research-
ers depend on accurate measurement data as an
input to make realistic predictions and estimates
and to build models for analysis and simulations.
For the researcher, the measurements of today’s
Internet support the improvement of existing
technology and the development of new tech-
nologies.

Table 1.1 summarizes the need for measure-
ments for various actors on different time scales.

1.2 Collecting and Analyzing

Traffic Measurements

The measurement process can be divided into sev-

eral phases. First, the measurements are planned

based on the need of an actor. That is, the mea-

surements should be tailor-made for observing

specific parameters. Second, the measurement

infrastructure to collect and analyses measured

data is designed, developed and tested. Third,

the gathering of measurement data is performed.

Finally, the collected measurement data is post-

processed and analyzed. Figure 1.1 illustrates the

various phases of the measurement process.

In each phase the costs of measurements can be

grouped in measurement specific equipment

(hardware and software), network resources and

human resources. Measurement specific equip-

ment includes hardware (processing power, pri-

mary and secondary memory) and software that

is required to collect, handle and post-process

measurement data. The measurement functional-

ity can either be implemented on stand-alone

devices and/or integrated into the functionality

of the network nodes. Network resources include

bandwidth needed to collect and transport the

measurement data. Obviously, human resources

are needed in every phase of the measurement

process.

Figure 1.1 Phases of the

measurement process

Short term Medium term Long term

End-user Monitor SLAs1) Evaluate SLAs Select appropriate

Service and content providers

provider

Network operator Monitor SLAs Network Select peering networks

Detect and solve configuration Replace nodes and

problems in the Routing of packets increase capacity of links

network Change network architec-

ture and introduce new

technology

Vendor Test components Large scale tests Develop new products

Researcher Models for analysis and

simulations

Design new solutions

Table 1.1 Perspectives and

needs for measurements on

various time scales

1)SLA – service level agreement

Post-process

and analyses

data

Collect

measurement

data

Develop

measurement

infrastructure

Planning