Open Source Bandwidth Monitoring With MRTG

Like humans, devices and applications in enterprises are also adept in

socializing with each other. Each application is interconnected with the other

for optimum performance. What connects all these devices and applications

running on them is the network, wired or wireless. This is the age of mobility

and devices are no longer sitting at one place. They move around and at the same

time need to be connected, all this puts a lot of importance on connectivity

which in turn is dependent on bandwidth. No matter how good your machine is and

no matter how good your application is, if the bandwidth of your Internet

connection is low, you won't be able to enjoy smooth browsing and all investment

in machines and applications would seem to be waste.

The same logic applies to modern data centers. If WAN connectivity is

bottle-necked then nothing can be done to improve performance of applications

running inside the data center. One way of avoiding bottle-necks is to plan data

center activities according to availability. For planning one needs data. In

this story, we talk about open source bandwidth monitoring tools that help one

to know the patterns of bandwidth availability.

Implementing MRTG



The best way to analyze huge chunks of data to derive patterns is via

graphs, and this is what Multi Router Traffic Grapher does. MRTG is a free

software licensed under the GNUGP. It displays graphs of traffic moving through

SNMP devices in your network. So whether you have a router or a firewall all you

need is MRTG. It is written in 'Perl' and works on Unix/Linux as well as

Windows, and even Netware systems. Here, we used a Windows XP machine to run it.

To enable SNMP client network service on the local host, go to Start>Control Panel> Add or Remove Programs> Add/Remove Windows Component and check Management and Monitoring Tools.

This is the output of MRTG software. Here, besides the information like uptime and maximum speed one can also analyze traffic over five minutes, over a day, a week, and also over a year.

The tools needed to run MRTG on Windows XP include MRTG software that can be

downloaded from http://oss.oetiker.ch/mrtg/pub/?M=D. We used the latest stable

version ie 'mrtg-2.16.3.zip' file. Besides MRTG you also need Active Perl for

running MRTG. This can be downloaded from http://www.activestate.com/activeperl/

(ActivePerl-5.10.1.1007-MSWin32-x86-291969.msi). In order to view created graphs

from anywhere, we used Apache Web Server that can be downloaded from http://httpd.apache.org/download.cgi#apache22

(apache_2.2.14-win32-x86-openssl-0.9.8k.msi). Once we have all the three

elements required, we can start with installing 'Perl' and 'Apache Web Server'

in their respective default paths. Once we have installed 'Perl,' we need to

check if a new Perl binary directory is listed in the system path. To do the

same go to Start> Right click My Computer> Properties> Advance tab> Environment

Variables and check for the following under System Variables:

PATH:

C:\Perl\site\bin;C:\Perl\bin;C:\Program



Files;C:\WINDOWS;C:\WINDOWS\System32

To check if Perl has been installed properly, go to command prompt and run

the following commands:

cd C:\Perl\eg



example.pl

And hit enter. You should get the following message:

Hello From ActivePerl!

If every thing is working fine, the next step is to extract

downloaded 'mrtg-2.16.3.zip' at 'C:\'. Once extracted we need to configure it.

Before that you need to check if MRTG is working properly. First we need to

enable SNMP client network service on the local host. For this, go to

Start>Control Panel> Add or Remove Programs> Add/Remove Windows Component and

put a check mark in front of Management and Monitoring Tools. Create a

'Test.pl' file at 'C:\mrtg-2.16.3\lib\mrtg2' and add the following code:

use BER;



use SNMP_Session;


# Return the uptime of the localhost to test SNMP


$host = "localhost";


$community = "public";


$oid = encode_oid(1,3,6,1,2,1,1,3,0); # Uptime


$session = SNMP_Session->open ($host, $community, 161)


|| die "Can't open SNMP session to localhost";


$session->get_request_response ($oid);


($bindings) = $session->decode_get_response ($session->{pdu_buffer});


($binding,$bindings) = &decode_sequence ($bindings);


($oid,$value) = &decode_by_template ($binding, "%O%@");


print &pretty_print($oid)," => ", &pretty_print ($value), "\n";

Now run the following command :

cd

C:\mrtg-2.16.3\lib\mrtg2



test.pl

This would show uptime of the machine. If everything is

working properly, it is time to create 'mrtg.cfg' file for monitoring traffic.

Run the following commands on command prompt to accomplish the same:



cd C:\mrtg-2.16.3\bin


perl cfgmaker public@192.168.5.25 > mrtg.cfg

Here '192.168.5.25' is the IP address of the router/machine

you are going to monitor (in our case it is a router). The next step is to

modify the 'mrtg.cfg' file so that it can dump output in a desired web server

folder (Apache in our case). We would also modify this file to continuously run

in the background. Open 'mrtg.cfg' in text editor and add the following lines

on top:

WorkDir:



C:\Progra~1\Apache~1\Apache2.2\htdocs



RunAsDaemon: yes

The path in front of 'WorkDir' is the path of Apache Web

Server. A key point to note here is that there should not be any spaces in this

path. This is the reason why we put 'Progra~1' instead of 'Program File'. Once

these changes have been saved, run the following commands:

cd C:\mrtg-2.16.3\bin



perl mrtg mrtg.cfg

One should get the following message on command prompt:

Daemonizing MRTG...



Do Not close this window. Or MRTG will die

Now open up your browser and go to the machine where MRTG

has been installed. This would show three graphs. The first graph is created to

show average traffic over five minutes while the other three have been created

for traffic movement over a week, month and year respectively. Besides traffic

graphs, one also comes to know about the uptime of router and maximum speed on

top.

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