PS:  This chart combines the ingress and egress throughput and displays the 
total throughput.  IE:  I currently have 21Mb/s egress and 11Mb/s ingress, and 
Network Load Stats is showing me 31Mb/s.

Also - it is bits - not Bytes.

G


-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Gary Gatten
Sent: Thursday, February 28, 2008 9:58 AM
To: [email protected]
Subject: Re: [Ntop] total traffic understanding -chart andtable Discrepancies

That's what I thought - but wanted to make sure.  This has always been accurate 
for me and I've tested using Iperf to blast all different type of tcp/udp 
traffic, different frame sizes, etc.

You need to make sure netflow is properly configured on your router.  Depending 
on your IOS you'll have different options.  Older versions netflow only counts 
output from an interface, so to account for all traffic you would need to 
enable netflow on at least two interfaces.  Newer IOS you can enable ingress 
and egress on the same interface.

Check that out or post the netflow config from your router.

G


-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Redder,Greg
Sent: Thursday, February 28, 2008 9:44 AM
To: [email protected]
Subject: Re: [Ntop] total traffic understanding -chart andtable Discrepancies


Hi Gary,

I'm sure I have something misconfigured or I am misinterpreting the output, but 
I go to the Summary Menu and choose "Network Load".  The graph  I was referring 
to and was in the attached pictures on the original message come from the "Last 
10 Minutes throughput" graph:  http://x.x.x.x/thptStats.html

..And yes, cricket is doing the math to convert the bytes to bits on the graphs 
I'm using for comparison.

I have tried this with both Firefox and IE.  I don't think it's a refresh 
issue, because if I stop the flows coming into the ntop box, the graphs go to 0 
pretty quickly and start to graph traffic again as soon as I turn the flows 
back on.

Not sure what I'm missing here but, thanks! --Greg

-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Gary Gatten
Sent: Wednesday, February 27, 2008 3:42 PM
To: [email protected]
Subject: Re: [Ntop] total traffic understanding - chart andtable Discrepancies

I've done extensive testing with netflow and nTop throughput and have found it 
to be pretty accurate "most" of the time.  Better stated, there's only been a 
few instances where the numbers were WAY off and I think it had/has something 
to do with the refresh rate of the browser.

The SNMP MIB actually tracks "Octets" (roughly bytes) tx and rx.  If Cricket is 
displaying things in bps, it's doing the math internally.

When you say the nTop "Network Throughput Graph" - what's the link/URL you're 
using?  I want to make sure we're talking about the same thing and then I'll 
try to help.

The rrd history is ... "whacked" - but the realtime stats (per host and global 
network) have been accurate for me using netflow.

G


-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Redder,Greg
Sent: Wednesday, February 27, 2008 4:19 PM
To: [email protected]
Subject: Re: [Ntop] total traffic understanding - chart andtable Discrepancies


Gary, Fernando, NTOP folks,

I've been noticing some similar discrepancies in the network throughput tables 
that are either a misunderstanding on my part or inaccuracy on the ntop part.  
It's important to note that my ntop boxes run on flow data and not sniffing the 
actual port.  I'm running ntop 3.2 on Fedora Core 6 boxes.

I have another snmp tool (Cricket) that polls our router's physical interface 
every 1 minute and graphs the input and output bits/sec and I have experience 
that shows this tool is highly accurate.  Last week, I noticed that one of the 
networks was at 90+Mbits/sec for over an hour.  However, the ntop throughput 
graph for that same network list quite a different number.  The network 
throughput graph in ntop listed a current throughput of 41.2M and an average of 
46.6M.   I've attached the graphs as reference.




If the 41.2M means megabytes  and there is a line for every 30 seconds on the 
10 Minute graph, that means 41.2Megabytes went through in 30 seconds which 
equals 11Mbits/sec.

Now, if the 41.2 is Megabits/sec, that's wrong too when I have a host pumping 
90Mbits one way into the link.  My load should be 90Mbits/sec plus whatever 
else is going in/out the link.

Maybe this is a problem with me using flowdata, but I have other ntop probes 
that sit "in-line" on the links they analyze and they are not accurate either.

Maybe I'm just not interpreting the graphs properly and maybe there's something 
I can do to help figure this out???

Thank you --Greg Redder
                Network Analyst
                Colorado State University

-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Gary Gatten
Sent: Wednesday, February 27, 2008 2:42 PM
To: [email protected]
Subject: Re: [Ntop] total traffic understanding - chart and table Discrepancies

I am now noticing a very similar instance to yours in "Global Protocol 
Distribution".  I have 88.7% TCP, 3.1% UDP 0% ICMP.  These percentages are 
accurate given the values:  Total IP is 9.6GB; TCP is 8.5GB; UDP is 303.3MB, 
ICMP is 1.3MB.  So, there's about 800MB worth of "other" data that's not 
accounted for which would also equal the missing 8%.



-----Original Message-----
From: Gary Gatten
Sent: Wednesday, February 27, 2008 3:14 PM
To: '[email protected]'
Subject: RE: [Ntop] total traffic understanding - chart and table Discrepancies

Unfortunately I can't answer your specific question.  I'd say rounding error, 
but your values are too far apart for that.

I have some similar type issues as well.  For example, the rrd data available 
with historical views isn't even close to the real-time and more accurate data. 
 Also, some of the counters within rrd contradict themselves.

My Summary Traffic says I have 99.9% unicast in the table, but the pie chart 
color tells me I have 99.9% MULTICAST.

There are a number of other anomalies that I can't recall right now.  I haven't 
spent as much time in the nTop GUI lately.

I wish I could remember all the issues more accurately.  I guess if it starts 
bothering me I'll setup a QA instance where I generate known volumes of traffic 
to predetermined hosts and make sure it's accounted for correctly.  Until then 
I'm not sure what to do...

Gary


-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Fernando Yamada
Sent: Wednesday, February 27, 2008 8:13 AM
To: [email protected]
Subject: [Ntop] total traffic understanding

Hello,

I'm having difficulties trying to understand total traffic sums on ntop.

For example, in "Global protocol distribution" I have a total of 2.4 GB
(99.9%) of IP traffic. Inside this IP traffic I have 2.1 GB (87.8%) of TCP, 
80.7 MB (3.3%) and ICMP/IGMP/Other IP, accouting 0% each.
Why doesn't the sum match? 87.8% + 3.3% does not equal to 99.9%

Also, on traffic directions -> Remote to Local IP, the Total Traffic does not 
match any other total.

I've search in the documentation about these issues with no success. If anyone 
can explain to me or indicate me something to read about, I'd appreciate.

Thanks in advance and regards,
--
Fernando Yamada
Via IP Soluções para Internet Ltda
+55 48 2106-6161
e-mail: [EMAIL PROTECTED]
MSN: [EMAIL PROTECTED]
Skype: suporte2viaip
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