Problem with RMON "delta" function - using ifHCInOctets

Unanswered Question
Aug 21st, 2007

Hi there,

I've set up an rmon alarm threshold for one of my 6500 Gi interfaces (see below). Unfortunatley, the "delta" sample result never triggers the alarm, since it's always way below what I expect. Furthermore, I notice far more negative values than what I would expect from the counters rolling over.

In order to confirm my threshold values and the counter reliability, I've performed some snmpget's over 1 minute and compared them with the interface counters on the Switch - all seems well with this!!

So in summary, is there a problem with the "delta" function within rmon ???


rmon event 1 log trap ******** description "BW Usage Exceeds 10%" owner abc

rmon event 2 trap ******** description "BW Usage Normalised" owner abc

rmon alarm 10 ifXEntry.6.94 60 delta rising-threshold 1100000000 1 falling-threshold 800000000 2 owner abc

Switch>sh rmon a

Alarm 10 is active, owned by tmpinf1

Monitors ifXEntry.6.94 every 60 second(s)

Taking delta samples, last value was 15576

Rising threshold is 1100000000, assigned to event 1

Falling threshold is 800000000, assigned to event 2

On startup enable rising or falling alarm

V:\>snmpget -v 2c -c ******** ifHCInOctets.9

IF-MIB::ifHCInOctets.94 = Counter64: 98252338209223

V:\>snmpget -v 2c -c ******** ifHCInOctets.9

IF-MIB::ifHCInOctets.94 = Counter64: 98252374419211

Switch#sh ver

Cisco Internetwork Operating System Software

IOS (tm) s72033_rp Software (s72033_rp-IPSERVICESK9_WAN-M), Version 12.2(18)SXF3, RELEASE SOFTWARE (fc1)

Technical Support:

Copyright (c) 1986-2006 by cisco Systems, Inc.

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a1elmi123 Tue, 08/28/2007 - 05:40

Thanks for the reply. I've seen this doc before. Although very useful, it doesn't tackle the problem I'm seeing with the RMON delta function, when making use of the ifHCInOctets object.

Using SNMPgets on a 10Gb int every minute, shows decent variations (10^8). However, performing RMON delta's (1 min) gives very low values (10^4)!!



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