[mrtg] [Fwd: Re: MRTG-bugs]

Lyle Giese lyle at lcrcomputer.net
Wed Dec 17 22:25:28 CET 2008

nangineni praneeth wrote:
> sorry for not being clear......I was using MRTG with rateup and i set 
> the poll for every 5 minutes...I was monitoring tcp connections and as 
> well as inbound and outbound traffic...I just gave an example on 
> established tcp connections to show how MRTG is representing the green 
> colour graph(showing everything from zero instead of a constant 
> line)...Yes i do know that MRTG assumes zeroes in absense of 
> traffic.But i have checked the logfile and there were no zeroes at 
> all... This log file shows the entries of the number of tcp 
> connections established...........
Not absence of traffic, but absence of data in your data files(for a 
time period).  minor but significant difference to MRTG & rateup.
> it shows  8 8 8 8
>               8 8  8 8
> until i polled for the last time
This snippet shows the data, but not the timestamps on them. And you did 
not post the captions against the graphs so we can see what the green 
portion represented.  And the green uses a fill method in the graphs, 
painting the area under the lines.  I also suspect you will have better 
control over the graphing if you convert to rrd and use a frontend like 
routers2 to make the graphs.


> This is my configfile.........
> Target[tcp]: . at server
> maxbytes[tcp]: 100
> options[tcp]:gauge,nopercent,integer,noo
> So as  i understand since the logfile is showing constant entries MRTG 
> should also graph a constant line but instead it was showing graphs 
> starting from zero........But if i represnt the graph by hiding the 
> first variable(that is green colour graph) it is showing a constant line
> The values below the graph were like
> tcp connections; max: 8 connections average:8 connections current: 8 
> connections
> A cisco router traffic data is for all traffic.  A cisco router does 
> not know how to separate http traffic from ftp traffic.  A cisco 
> router can only show total traffic.
> The only traffic i was using in my lab environment was ftp 
> traffic........yeah cisco router traffic includes cdp traffic,ftp 
> traffic...........But MRTG was reporting higher traffic rate than the 
> cisco router is showing
> Regards
> Venkat
> --- On *Thu, 12/18/08, Lyle Giese /<lyle at lcrcomputer.net>/* wrote:
>     From: Lyle Giese <lyle at lcrcomputer.net>
>     Subject: [mrtg] [Fwd: Re: MRTG-bugs]
>     To: mrtg at lists.oetiker.ch
>     Date: Thursday, December 18, 2008, 2:19 AM
>     I did it again.  Forgot to include the list in my reply.
>     Lyle
>     -------- Original Message --------
>     Subject: 	Re: [mrtg] MRTG-bugs
>     Date: 	Wed, 17 Dec 2008 14:42:28 -0600
>     From: 	Lyle Giese <lyle at lcrcomputer.net>
>     To: 	nangineni praneeth <nv_2030 at yahoo.com>
>     References: 	<764194.96446.qm at web65708.mail.ac4.yahoo.com>
>     nangineni praneeth wrote:
>>     Hello everyone
>>                           ... I am using MRTG in my masters project
>>     and i think i have noticed few errors in it...........
>>     1) I have calculated the log file entries in the log file and
>>     took the average over the time for which i ran MRTG.......The
>>     value which it shows it different from the value which it
>>     graphed....Ther were couple of people who posted this question on
>>     the mrtg forum but no one has replied....So does anyone think
>>     this is a error or the way i am calculating it is wrong
>>     2) I posted this on the MRTG forum and one of them tried to give
>>     me an explanation for this.......its  with the green colour
>>     traffic....the traffic is showing as if it starts from
>>     zero....because i limited the amount of traffic the server sends
>>     to 4kBPs so i must see a constant line(or sawtooth like graph) on
>>     MRTG graphs but everything starts from zero......i have checked
>>     my logfile and there are no zeroes in it.........But the outbound
>>     traffic is showingup correctly like a sawtooth waverform(because
>>     of TCP).........The same thing happened when i was monitoring TCP
>>     connections on the server i suppressed the blue colour graph and
>>     the same story every sample MRTG is graphing starts from
>>     zero..........I am attaching a png image so that everyone can
>>     understand it better
>>     3)  I am using cisco router and when i saw the 5 min average
>>     input rate and output rate..The values are different from the
>>     values MRTG is reporting.................I have checked this many
>>     times.......
>>     ....I ran MRTG  continuously for 15 hours and and found these things
>>     Regards
>>     Venkat
>     You have not explained what or how you collected this data.  MRTG
>     & rateup, in the absence of data, assumes a zero for the time
>     period.  MRTG & rateup default to a 5 min sample rate. 
>     You state you were collecting traffic from this device somehow,
>     but the graph below shows connections, which is not the same as
>     traffic. 
>     Unless you have written a special tool to collect ftp only
>     traffic, the normal snmp data available is for total traffic only.
>     A cisco router traffic data is for all traffic.  A cisco router
>     does not know how to separate http traffic from ftp traffic.  A
>     cisco router can only show total traffic.
>     In other words, you have made some statements as to what you think
>     are errors, but you have not provided any background as to how the
>     data was collected, graphed, and what parameters were feed into
>     MRTG & rateup.
>     Lyle Giese
>     LCR Computer Services, Inc.
>>     ------------------------------------------------------------------------

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