You are probably encountering counter wrap issues. If you are polling 32-bit SNMP counters, the counter will hit its limit (2^32) and "wrap" back to 0 once every 5 minutes if the traffic on that interface is at 2^32/300=1,431,6558 octets (bytes) per second (109.22 Mbps). MRTG can handle a single wrap per polling interval. However, if you sustaining over 300 Mbps, the counter will wrap every 109.22 seconds.
This is a limitation of the SNMP Counter, NOT MRTG. You have two options: Set your polling interval to poll more frequently and use RRDTool (MRTG with Rateup has a minimum of 5 minute polling interval so you must use RRDTool to poll more frequently) or use your device's 64-bit counters. Hopefully you can do the latter and your device has 64-bit counters as that would be an easy fix. With using a 64-bit counter, you won't have a wrap problem in a 5-minute polling interval unless you exceed 469,124,961,184 Mbps. :-) Hope this helps. Eric Brander ACS Texas CHIP Account Sr. Communications Engineer - Information Systems Department 512.336.3331 Eric dot Brander at acs-inc dot com -----Original Message----- From: Paul Polichronakis [mailto:[EMAIL PROTECTED] Sent: Wednesday, January 29, 2003 6:28 PM To: [EMAIL PROTECTED] Subject: [mrtg] Bandwidth Monitoring I have MRTG set up on a Win2000 machine to monitor 2 Cisco Routers (a 3640 and a 4500) along with 4 switches (a baynetworks 350T, and 3 Cisco 5505s). I cannot seem to figure out why the machine is reporting such low results (I have attached a link to a copy of one graph). This graph is the interface of a 6 meg pipe that I know atleast 3 meg are being used constantly. Does anyone have any ideas what may not be configured correctly? <img src="http://www.polynetworks.com/64.200.229.134_7-day.png";> http://www.polynetworks.com/64.200.229.134_7-day.png Thanks, Paul -- Unsubscribe mailto:[EMAIL PROTECTED] Archive http://www.ee.ethz.ch/~slist/mrtg FAQ http://faq.mrtg.org Homepage http://www.mrtg.org WebAdmin http://www.ee.ethz.ch/~slist/lsg2.cgi -- Unsubscribe mailto:[EMAIL PROTECTED] Archive http://www.ee.ethz.ch/~slist/mrtg FAQ http://faq.mrtg.org Homepage http://www.mrtg.org WebAdmin http://www.ee.ethz.ch/~slist/lsg2.cgi
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