Traffic measurement is an essential tool to guide the operators
of large IP networks in detecting and diagnosing performance
problems, and evaluating potential control actions.
Measurements help operators identify underprovisioned links,
denial-of-service attacks, flash crowds, and shifts in user
demands. This tutorial focuses on measurement techniques and
traffic models that provide a comprehensive view of large IP
networks where the operator has full administrative control.
The tutorial starts with a brief overview of the basic tasks
involved in operating a large IP network and derives
requirements for network measurement. We argue that the very
properties responsible for the Internet's success also make
it difficult to control and manage.
Next, we present a comprehensive survey of the passive
measurement techniques currently available in IP networks.
We present an overview of SNMP/RMON, packet monitoring, and
flow-level measurement. We classify these measurements
according to their temporal and spatial granularity, their
means of collection, and their overhead, and discuss how to
exploit the measurement data in important operational tasks.
Then, we focus on complex traffic engineering tasks that
require combining multiple types of measurement data from
different locations in the network. First, we describe network
tomography, a technique for inferring a traffic matrix from
link utilization statistics. Second, we describe how to
compute point-to-multipoint traffic demands by combining
flow-level measurements with routing table data. Third,
we describe packet sampling techniques for direct observation
of the path matrix.
Copyright. All Rights Reserved.