[mrtg] Re: new to MRTG
H1STEINH at hewitt.com
Mon May 29 06:13:06 MEST 2000
You basicly asked - How do I compare the results from the HP LanAnalyzer and
-- It depends on what you are trying to see. :-)
The LanAnalyzer time frame is what ? 5 seconds or even 1 second ? The MRTG
time frame is 5 minutes. So the difference you see is the effect of Bursty
traffic. Nice to know, but not all the useful for most studies. IF you cut the
time line fine enough you will find it is 100% in use. The question is how
often is it that high? I have seen that over the 5 minute interval is often a
great value since you have this over a 24 hour period. The LanAnalyzer might
record it over a 24 hour period, but that will be for only one segment at a
time. MRTG is for the whole network.
For those segments that are high, then you can use the LanAnalyzer to zero in on
those stations that need attention. Use MRTG to see where you need to spend
Errors can be tracked in MRTG. You just need to know the OID or SNMP MIB to
call to get the information. Most of the current releases of MRTG have the
ifError values in the list. Read the source and you can find what OID name you
need to use.
? The 2948G-L3 switch ? If you have the MIB for the CPU value, then poll that
MIB / OID and you will have the values you need. Some of the MIBs code it as a
1 minute value, 5 minute value and a 10 or 30 minute value. Plotting the 1
minute and 5 minute value would show you how spread the utilization is.
If you look up the MMG modeling equations and check out the queueing effects at
30% busy, you will see why most people recomend that you need to do something at
that level of usage. At that point the queueing begins to be larger than the
service time. ie you wait longer than you actually need service.
To find the MIB / OID you may need to use a SNMPwalk type of program. A very
good one is Getif mentioned in this list.
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