Difference between displayed & consumed flow on RaspberryPi2

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cola33
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Difference between displayed & consumed flow on RaspberryPi2

#1 Post by cola33 » Sat Oct 10, 2015 7:37 pm

Hello,

I installed Cacti v.0.97c with Weathermap plugin on a Raspberry Pi 2 Model B, and I found a curious problem :
When I transfer data at 700 Mbps approximately between 2 nodes for 5 minutes (Interval Poller I defined) Weathermap tells me 60 Mbps between two nodes and Cacti graphs corresponding to two links also tells me 60 Mbps.

Can you help me for solve my problem (I'm hopeless) ?

Edit 1 : The Realtime plugin shows me the right values ​​for the traffic.

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Howie
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Re: Difference between displayed & consumed flow on Raspberr

#2 Post by Howie » Sun Oct 11, 2015 4:04 am

It's not really a weathermap thing, but make sure you are using 64-bit counters for your interface statistics. 32-bit counters can't measure more than about 112Mbit/sec over five minutes. Anything higher will show as a figure lower than 112.

The reason is that Cacti gets the number of bytes transferred from the device (A), then asks again in 5 minutes (B), and then figures out (B-A)/300 * 8 (300 seconds in 5 minutes, 8 bits in a byte). If the result is negative, it can guess that the counter has wrapped around in the meantime and adjust, but there's no way it can tell if it wrapped more than once.

Realtime is polling every few seconds, so it doesn't have this issue.
Weathermap 0.98 is out! & QuickTree 1.0. Superlinks is over there now (and built-in to Cacti 1.x).
Some Other Cacti tweaks, including strip-graphs, icons and snmp/netflow stuff.
(Let me know if you have UK DevOps or Network Ops opportunities, too!)

cola33
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Joined: Sat Oct 10, 2015 7:31 pm

Re: Difference between displayed & consumed flow on Raspberr

#3 Post by cola33 » Sun Oct 11, 2015 10:07 am

I have a pass on 64 bits all the equipement and I have only one switch who have a good graph generated.
The others are blank.

I have :
- 1 HP Procurve 2810-24G (good now with 64 bits)
- 1 HP Procurve 1810-24G (not generate graph on 64 bits)
- 1 Cisco Small Business RV180 (not generate graph on 64 bits)

I have verified on the two last equipment with "snmpwalk" for list all mib available and I don't found "Counter64". I found only "Counter32"

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Re: Difference between displayed & consumed flow on Raspberr

#4 Post by Howie » Sun Oct 11, 2015 11:04 am

Then you may be out of luck - even with 1 minute polling I don't think you can get to 700mbit/sec with 32-bit counters.

Just to confirm - with 32-bit counters, you get a graph but with incorrect values, right? If you are getting no data at all, it's probably something else (like the maximum number of OIDs per SNMP query being too high).

I believe you need to use SNMP v2c to get counter64, too. It's worth checking that if it's an option you haven't tried.
Weathermap 0.98 is out! & QuickTree 1.0. Superlinks is over there now (and built-in to Cacti 1.x).
Some Other Cacti tweaks, including strip-graphs, icons and snmp/netflow stuff.
(Let me know if you have UK DevOps or Network Ops opportunities, too!)

cola33
Posts: 3
Joined: Sat Oct 10, 2015 7:31 pm

Re: Difference between displayed & consumed flow on Raspberr

#5 Post by cola33 » Sun Oct 11, 2015 11:46 am

Just to confirm - with 32-bit counters, you get a graph but with incorrect values, right?
Yes in 32 bit counter i have a graph but with incorrect values... :(

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Re: Difference between displayed & consumed flow on Raspberr

#6 Post by Howie » Sun Oct 11, 2015 12:14 pm

OK, then if you don't have Counter64 with v2c of SNMP, you are a little bit stuck. Thank your switch vendor :-/

With 1 minute polling you will get up to about 580Mbit/sec I think (5x114).

But please do try your snmpwalk with -v2c if you haven't (the default is v1), just to be sure. The counters you need are in the ifXTable, I think (ifHcInOctets and ifHcOutOctets).

More info here: http://forums.cacti.net/viewtopic.php?t=24526
Weathermap 0.98 is out! & QuickTree 1.0. Superlinks is over there now (and built-in to Cacti 1.x).
Some Other Cacti tweaks, including strip-graphs, icons and snmp/netflow stuff.
(Let me know if you have UK DevOps or Network Ops opportunities, too!)

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