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Re: Network Monitoring

To: nv-l@lists.tivoli.com
Subject: Re: Network Monitoring
From: Leslie Clark <lclark@US.IBM.COM>
Date: Thu, 16 Sep 1999 09:28:14 -0400
Here's one of my old appends...

Expression in /usr/OV/conf/mibExpr.conf  (from my notebook...)

For lans, measure both send and receive, since data only flows in one
direction at a time (half-duplex):

LANIf%Util \
"% interface utilization from                          \
((ifInOctets + ifOutOctets) * 8 * 100) / ifSpeed"      \
                            .1.3.6.1.2.1.2.2.1.10.     \
                            .1.3.6.1.2.1.2.2.1.16. +   \
                            8 * 100 *                  \
                            .1.3.6.1.2.1.2.2.1.5. /
For WANs, measure separately, since data flows both ways at once (full-duplex):

WANIf%RecvUtil -
"% interface utilization from                          \
(ifInOctets * 8 * 100) / ifSpeed"                      \
                            .1.3.6.1.2.1.2.2.1.10.     \
                            8 * 100 *                  \
                            .1.3.6.1.2.1.2.2.1.5. /

WANIf%SendUtil -
"% interface utilization from                          \
(ifOutOctets * 8 * 100) / ifSpeed"                     \
                            .1.3.6.1.2.1.2.2.1.16.     \
                            8 * 100 *                  \
                            .1.3.6.1.2.1.2.2.1.5. /

My notes on what to use when for WANs:
A 56kb line can send 56kb and receive 56kb at the same time. So in one
sense its capacity is 112kb, but not really, since neither can use more
than 56kb. Two methods:
1) Take the highest: util = max(wansend,wanrecv)
This tells you how close you are to the limit, regardless of the
direction that is being a pig.
2) Take the average or double the speed:
 util=8*(inoctets+outoctets)/(ifspeed*2)*100
This gives effective util of entire link, but is deceptive about how
close you are to capacity. Eg 99% send and 21% receive would show as
60% util, but you are really maxxed on the send side.

Cordially,

Leslie A. Clark
IBM Global Services - Systems Mgmt & Networking


Thank you Leslie,
I did what you wrote ( the mibExpr.conf and the snmpCollect ).
Where can i find an  expretions ? for instance : a WAN utilization expr ( i
guess it isn't the same as a LAN) and a switch half duplex port expr.
Neither one of those vendors gives a utilization value in their mibs.


Greetings, Oren.


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