Low Bandwidth Reading from Cisco Switches

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arnab.roy
Posts: 354
Joined: Sat Apr 30, 2011 10:24 am

Low Bandwidth Reading from Cisco Switches

Post by arnab.roy »

Hi Guys,

I am facing a weird issue, our customers are complaining that bandwidth graphs are showing low readings, althought the contour of the graph is similar to their expectations but the scale is wrong. I am running r1.8. The port that we are monitoring is a cisco gigabit port. Anybody knows how I can proceed with troubleshooting this. I am using the switch monitoring wizard and does detect the correct port speed so I am a bit confused. Any help would be appreciated.

Cheers
Arnab
lanware
Posts: 10
Joined: Mon Oct 03, 2011 11:53 am

Re: Low Bandwidth Reading from Cisco Switches

Post by lanware »

Are you using SNMP v2c? There's a caveat with needing to use 64bit counters for Cisco interfaces:

http://www.cisco.com/en/US/tech/tk648/t ... 69ac.shtml

Check the plugin to see if there's an extra switch for setting 32 or 64 bit counters. SNMP v2c introduced a 64 bit counter, so maybe just setting this will work fine.
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nscott
Posts: 1040
Joined: Wed May 11, 2011 8:54 am

Re: Low Bandwidth Reading from Cisco Switches

Post by nscott »

Also, on top of lanware's question, is it orders of magnitude off or just a scalar factor off?
Nicholas Scott
Former Nagios employee
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arnab.roy
Posts: 354
Joined: Sat Apr 30, 2011 10:24 am

Re: Low Bandwidth Reading from Cisco Switches

Post by arnab.roy »

Hi Guys,

I am aware of the Cisco 64 bit counter issue, unfortunately the way XI seems to grab the graphs from mrtg , isnt very straightforward if I understand it converts mrtg->rrd-> check rrdtraf ....then dumps the output into nagios perfdata format, which pnp then converts into graphs. Can you point me where / how I can see the actual output graphs from mrtg? I dont see the standard mrtg html output anywhere?

Cheers
Arnab
mguthrie
Posts: 4380
Joined: Mon Jun 14, 2010 10:21 am

Re: Low Bandwidth Reading from Cisco Switches

Post by mguthrie »

The mrtg rrd files are in:
/var/lib/mrtg

You can query any rrdfile and fetch "Today's" information by running:

Code: Select all

rrdtool fetch </path/to/rrdfile> AVERAGE
mrtg.cfg is at /etc/mrtg/mrtg.cfg