Traffic engineering based on passive measurements of ... - CNL

<strong>Traffic</strong> <strong>engineering</strong> <strong>based</strong> on passive measurements of
computer networks performance parameters.
Ondrej Roháľ
supervisor: Ing. Juraj Giertl.
Department of Computer and Informatics,
Technical University of Košice, Lentá 9, 041 20 Košice,
Slovak Republic.
E-mail: ondrej.rohal@gmail.com
ABSTRACT
This work explores optimalization of network
traffic <strong>based</strong> on passive measurements. These
measuremants provide very usefull information that
can be used to optimize network traffic, by using
tools of EIGRP protocol to manage network traffic.
The goal of this work is implementation of
optimization system, which can work with data
collected by BasicMeter [4], exported in IPFIX
format.
1. PROBLEM ANALYSIS
The main goals of <strong>Traffic</strong> <strong>engineering</strong> [1, 2, 3, 5]
are to improve overall network performance by
optimalization of resources in the network. The
general goals of network optimalization are:
Minimize congestion in network and
prevent packet loss.
Improvement of network utilization
Minimalization of delays experienced by
packets.
Increasing the number of network users
with current hardware.
Congestion of traffic lines is one of the most
difficult problems that network service providers face.
There are two main factors that have caused network
congestion. Inadequate network resources can not
accommodate traffic that far exceeds technical limits.
Another thing is that these resources are not evenly
used, means that traffic in network is unbalanced.
Then it is just question of optimal network
management. Here there is space for optimalization.
Critical situation is the specific situation
called “fish problem” [1]. Fish problem is about
multiple possible paths to the destination. Problem is
to split traffic evenly between there multiple paths.
This work is concentrated on balancing traffic in
networks to achieve better utilization of links
bandwidth or better overall delay for packet travel.
2. REALIZATION PROPOSAL
Goal of this work is to create program that will be
used as automated tool for optimalization. Generally
said it is experiment to use application layer of OSI
model to influence routers how to do their decisions.
It is using data measured by “BasicMeter”, tool for
passive measuring in computer networks created by
students in CNL (Computer networks laboratory) of
Technical University of Košice. Automat will be its
component for practical application of its data.
Program will be created from these blocks:
Data measured by BasicMeter
Topology
<strong>Traffic</strong> Demands
Storage database for data
Network interface
Graphic interface
BasicMeter Topology Demands
Algorithms
System data (Database)
Network Interface
Graphic Interface
Figure 1. Overview of the optimization system
Parameters measured by BasicMeter: we need to
monitor used bandwidth and actual one way delay.
Another possible data are jitter or packet loss. This
data are storage by database.
Topology: it is necessary in some level to have
information about routers and their topology. For
current tasks of this program it is not necessary to
have complete view of network, but future updates
will possibly need it. For that purpose it can be used
algorithms from “Synets” [6], project created by
students in CNL (Computer networks laboratory) of
Technical University of Košice.

Demands: will be possible to change in time, <strong>based</strong> on
actual demands in network. Main two demands are to
split used bandwidth across the network or achieve
best delay for packets.
System data: it means all data from certain time frame
measured by BasicMeter. From this data it is possible
to compute costs of links with high accuracy, and
possibly find links oscillations that can be balanced by
load balancing.
Algorithms: this part is most important. The basic goal
of this program is to calculate weights of EIGRP
metrics by measuring data traffic, then implement new
costs of link into the network. For this purpose we
need tools to communicate with routers.
At first we need to summarize data from the
BasicMeter. It is filling database with data such as
used average bandwidth and one way delay for links
between routers. According to these two parameters
the cost will be calculated for each interface of router.
Cost of links will be recalculated in certain time
intervals. The shorter interval it will be, the better this
method will provide more effective routing in
networks. The links metrics will be matching actual
traffic in network.
Each time interval there will be set of
procedures, which will compute actual average
bandwidth and latency. These data can be set into the
matrix. Matrix is generally representation of the net.
Bandwidth and latency have separately matrixes of
values. By comparing values in matrixes we can
calculate final cost of the each link.
It is necessary to conduct load balancing on
some routes, where program discovers traffic
oscillations between routers ports like it is observed in
“fish problem”. It can be detected by comparing few
measurements in some time frame. Then by using
tools of EIGRP protocol it is possible to eliminate this
problem. Program will split traffic into multiple paths
by ratio that will use optimally all possible routes to
destination.
Network interface: this part of program is dedicated to
implementations of measured and computed values.
Algorithm should communicate with routers to set
new values of metric into their configuration. First
there will be generated commands for routers, and
then these commands will be by Telnet session
transmitted on routers. It could do so by itself or using
other existing tools.
Graphic interface: this part is not necessary for basic
function. It can be designed in different levels. In this
work it is just basic interface between user and main
program. Graphic interface will be integrated in
BasicMeter graphical interface situated on users
computer. This interface can control main program
that is situated on server with database, to improve
processing speed. This interface should provide initial
settings of program, information about actual changes
in routers configurations and interface to regulate
running algorithms.
3. CONCLUSION
This program can provide interesting application
of data measured by BasicMeter. It is experimenting
with EIGRP protocol features for network
management, to achieve optimalization changes in
network traffic.
It is necessary to test this system and discover its
properties and weaknesses, and evaluate effectiveness
of these algorithms. Also it is necessary to test time
intervals how fast can these changes be applied into
network and what will be effect in real world.
4. REFERENCES
[1] Zheng Wang : Internet Qos Architectures &
Mechanisms 2001 ISBN10: 1558606084
[2] A. Maltz, Geoffrey Xie, Jibin Zhan: Routing
Design in Operational Networks: A Look
from the Inside, Carnegie Mellon University
2004
URL:http://www.sigcomm.org/sigcomm2004
/papers/p500-maltz11.pdf
[3] Lili Qiu, Yang Richard Yang,Yin
Zhang,Scott Shenker : On Selfish Routing in
Internet-Like Environments, 2003
URL:http://www.sigcomm.org/sigcomm2003
/papers/p151-qiu.pdf
[4] André, M. : Meranie a vzorkovanie
Prevádzkových parametrov v počítačových
sieťach. Diplomová práca, KPI FEI TUKE,
2004.
[5] Shin-Jer Yang and Hung-Cheng Chou:
Adaptive QoS parameters approach to
modeling Internet performance, 2003
[6] Ungvarský, I.: Nástroj na analýzu topológie
siete. Diplomová práca, KPI FEI TUKE,
2006.