Traffic engineering based on passive measurements of ... - CNL
Traffic engineering based on passive measurements of ... - CNL
Traffic engineering based on passive measurements of ... - CNL
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<str<strong>on</strong>g>Traffic</str<strong>on</strong>g> <str<strong>on</strong>g>engineering</str<strong>on</strong>g> <str<strong>on</strong>g>based</str<strong>on</strong>g> <strong>on</strong> <strong>passive</strong> <strong>measurements</strong> <strong>of</strong><br />
computer networks performance parameters.<br />
Ondrej Roháľ<br />
supervisor: Ing. Juraj Giertl.<br />
Department <strong>of</strong> Computer and Informatics,<br />
Technical University <strong>of</strong> Košice, Lentá 9, 041 20 Košice,<br />
Slovak Republic.<br />
E-mail: <strong>on</strong>drej.rohal@gmail.com<br />
ABSTRACT<br />
This work explores optimalizati<strong>on</strong> <strong>of</strong> network<br />
traffic <str<strong>on</strong>g>based</str<strong>on</strong>g> <strong>on</strong> <strong>passive</strong> <strong>measurements</strong>. These<br />
measuremants provide very usefull informati<strong>on</strong> that<br />
can be used to optimize network traffic, by using<br />
tools <strong>of</strong> EIGRP protocol to manage network traffic.<br />
The goal <strong>of</strong> this work is implementati<strong>on</strong> <strong>of</strong><br />
optimizati<strong>on</strong> system, which can work with data<br />
collected by BasicMeter [4], exported in IPFIX<br />
format.<br />
1. PROBLEM ANALYSIS<br />
The main goals <strong>of</strong> <str<strong>on</strong>g>Traffic</str<strong>on</strong>g> <str<strong>on</strong>g>engineering</str<strong>on</strong>g> [1, 2, 3, 5]<br />
are to improve overall network performance by<br />
optimalizati<strong>on</strong> <strong>of</strong> resources in the network. The<br />
general goals <strong>of</strong> network optimalizati<strong>on</strong> are:<br />
<br />
<br />
<br />
<br />
Minimize c<strong>on</strong>gesti<strong>on</strong> in network and<br />
prevent packet loss.<br />
Improvement <strong>of</strong> network utilizati<strong>on</strong><br />
Minimalizati<strong>on</strong> <strong>of</strong> delays experienced by<br />
packets.<br />
Increasing the number <strong>of</strong> network users<br />
with current hardware.<br />
C<strong>on</strong>gesti<strong>on</strong> <strong>of</strong> traffic lines is <strong>on</strong>e <strong>of</strong> the most<br />
difficult problems that network service providers face.<br />
There are two main factors that have caused network<br />
c<strong>on</strong>gesti<strong>on</strong>. Inadequate network resources can not<br />
accommodate traffic that far exceeds technical limits.<br />
Another thing is that these resources are not evenly<br />
used, means that traffic in network is unbalanced.<br />
Then it is just questi<strong>on</strong> <strong>of</strong> optimal network<br />
management. Here there is space for optimalizati<strong>on</strong>.<br />
Critical situati<strong>on</strong> is the specific situati<strong>on</strong><br />
called “fish problem” [1]. Fish problem is about<br />
multiple possible paths to the destinati<strong>on</strong>. Problem is<br />
to split traffic evenly between there multiple paths.<br />
This work is c<strong>on</strong>centrated <strong>on</strong> balancing traffic in<br />
networks to achieve better utilizati<strong>on</strong> <strong>of</strong> links<br />
bandwidth or better overall delay for packet travel.<br />
2. REALIZATION PROPOSAL<br />
Goal <strong>of</strong> this work is to create program that will be<br />
used as automated tool for optimalizati<strong>on</strong>. Generally<br />
said it is experiment to use applicati<strong>on</strong> layer <strong>of</strong> OSI<br />
model to influence routers how to do their decisi<strong>on</strong>s.<br />
It is using data measured by “BasicMeter”, tool for<br />
<strong>passive</strong> measuring in computer networks created by<br />
students in <strong>CNL</strong> (Computer networks laboratory) <strong>of</strong><br />
Technical University <strong>of</strong> Košice. Automat will be its<br />
comp<strong>on</strong>ent for practical applicati<strong>on</strong> <strong>of</strong> its data.<br />
Program will be created from these blocks:<br />
<br />
<br />
<br />
<br />
<br />
<br />
Data measured by BasicMeter<br />
Topology<br />
<str<strong>on</strong>g>Traffic</str<strong>on</strong>g> Demands<br />
Storage database for data<br />
Network interface<br />
Graphic interface<br />
BasicMeter Topology Demands<br />
Algorithms<br />
System data (Database)<br />
Network Interface<br />
Graphic Interface<br />
Figure 1. Overview <strong>of</strong> the optimizati<strong>on</strong> system<br />
Parameters measured by BasicMeter: we need to<br />
m<strong>on</strong>itor used bandwidth and actual <strong>on</strong>e way delay.<br />
Another possible data are jitter or packet loss. This<br />
data are storage by database.<br />
Topology: it is necessary in some level to have<br />
informati<strong>on</strong> about routers and their topology. For<br />
current tasks <strong>of</strong> this program it is not necessary to<br />
have complete view <strong>of</strong> network, but future updates<br />
will possibly need it. For that purpose it can be used<br />
algorithms from “Synets” [6], project created by<br />
students in <strong>CNL</strong> (Computer networks laboratory) <strong>of</strong><br />
Technical University <strong>of</strong> Košice.
Demands: will be possible to change in time, <str<strong>on</strong>g>based</str<strong>on</strong>g> <strong>on</strong><br />
actual demands in network. Main two demands are to<br />
split used bandwidth across the network or achieve<br />
best delay for packets.<br />
System data: it means all data from certain time frame<br />
measured by BasicMeter. From this data it is possible<br />
to compute costs <strong>of</strong> links with high accuracy, and<br />
possibly find links oscillati<strong>on</strong>s that can be balanced by<br />
load balancing.<br />
Algorithms: this part is most important. The basic goal<br />
<strong>of</strong> this program is to calculate weights <strong>of</strong> EIGRP<br />
metrics by measuring data traffic, then implement new<br />
costs <strong>of</strong> link into the network. For this purpose we<br />
need tools to communicate with routers.<br />
At first we need to summarize data from the<br />
BasicMeter. It is filling database with data such as<br />
used average bandwidth and <strong>on</strong>e way delay for links<br />
between routers. According to these two parameters<br />
the cost will be calculated for each interface <strong>of</strong> router.<br />
Cost <strong>of</strong> links will be recalculated in certain time<br />
intervals. The shorter interval it will be, the better this<br />
method will provide more effective routing in<br />
networks. The links metrics will be matching actual<br />
traffic in network.<br />
Each time interval there will be set <strong>of</strong><br />
procedures, which will compute actual average<br />
bandwidth and latency. These data can be set into the<br />
matrix. Matrix is generally representati<strong>on</strong> <strong>of</strong> the net.<br />
Bandwidth and latency have separately matrixes <strong>of</strong><br />
values. By comparing values in matrixes we can<br />
calculate final cost <strong>of</strong> the each link.<br />
It is necessary to c<strong>on</strong>duct load balancing <strong>on</strong><br />
some routes, where program discovers traffic<br />
oscillati<strong>on</strong>s between routers ports like it is observed in<br />
“fish problem”. It can be detected by comparing few<br />
<strong>measurements</strong> in some time frame. Then by using<br />
tools <strong>of</strong> EIGRP protocol it is possible to eliminate this<br />
problem. Program will split traffic into multiple paths<br />
by ratio that will use optimally all possible routes to<br />
destinati<strong>on</strong>.<br />
Network interface: this part <strong>of</strong> program is dedicated to<br />
implementati<strong>on</strong>s <strong>of</strong> measured and computed values.<br />
Algorithm should communicate with routers to set<br />
new values <strong>of</strong> metric into their c<strong>on</strong>figurati<strong>on</strong>. First<br />
there will be generated commands for routers, and<br />
then these commands will be by Telnet sessi<strong>on</strong><br />
transmitted <strong>on</strong> routers. It could do so by itself or using<br />
other existing tools.<br />
Graphic interface: this part is not necessary for basic<br />
functi<strong>on</strong>. It can be designed in different levels. In this<br />
work it is just basic interface between user and main<br />
program. Graphic interface will be integrated in<br />
BasicMeter graphical interface situated <strong>on</strong> users<br />
computer. This interface can c<strong>on</strong>trol main program<br />
that is situated <strong>on</strong> server with database, to improve<br />
processing speed. This interface should provide initial<br />
settings <strong>of</strong> program, informati<strong>on</strong> about actual changes<br />
in routers c<strong>on</strong>figurati<strong>on</strong>s and interface to regulate<br />
running algorithms.<br />
3. CONCLUSION<br />
This program can provide interesting applicati<strong>on</strong><br />
<strong>of</strong> data measured by BasicMeter. It is experimenting<br />
with EIGRP protocol features for network<br />
management, to achieve optimalizati<strong>on</strong> changes in<br />
network traffic.<br />
It is necessary to test this system and discover its<br />
properties and weaknesses, and evaluate effectiveness<br />
<strong>of</strong> these algorithms. Also it is necessary to test time<br />
intervals how fast can these changes be applied into<br />
network and what will be effect in real world.<br />
4. REFERENCES<br />
[1] Zheng Wang : Internet Qos Architectures &<br />
Mechanisms 2001 ISBN10: 1558606084<br />
[2] A. Maltz, Ge<strong>of</strong>frey Xie, Jibin Zhan: Routing<br />
Design in Operati<strong>on</strong>al Networks: A Look<br />
from the Inside, Carnegie Mell<strong>on</strong> University<br />
2004<br />
URL:http://www.sigcomm.org/sigcomm2004<br />
/papers/p500-maltz11.pdf<br />
[3] Lili Qiu, Yang Richard Yang,Yin<br />
Zhang,Scott Shenker : On Selfish Routing in<br />
Internet-Like Envir<strong>on</strong>ments, 2003<br />
URL:http://www.sigcomm.org/sigcomm2003<br />
/papers/p151-qiu.pdf<br />
[4] André, M. : Meranie a vzorkovanie<br />
Prevádzkových parametrov v počítačových<br />
sieťach. Diplomová práca, KPI FEI TUKE,<br />
2004.<br />
[5] Shin-Jer Yang and Hung-Cheng Chou:<br />
Adaptive QoS parameters approach to<br />
modeling Internet performance, 2003<br />
[6] Ungvarský, I.: Nástroj na analýzu topológie<br />
siete. Diplomová práca, KPI FEI TUKE,<br />
2006.