the definition of load from Cisco:
Load on the interface as a fraction of 255 (255/255 is completely
saturated), calculated as an exponential average over five minutes.
I don't personally have access to the formula, nor could I find it on
Cisco's website.
If this were a multiple choice problem on the certification exams, I'd rule
out answer 2, because neither input or output is comprehensive in and of
itself
If 'moving average' means exponential average, then I'd choose answer 1 in
conjunction with answer 3.
The utilization (based on the sh int load value) doesn't make any sense
*unless* the bandwidth parameter on the interface is set to reflect the
actual bandwidth of the circuit.
We had a tool once that extracted both the input/output bps averages and the
drops, and calculated *them* across a few seconds against the circuit
bandwidth - it gave us a little better granularity and accuracy, especially
if the drops corresponded with higher 'load'.
Also, my experience has been that as the sustained (not burst) pps/bps
interface utilization approaches the CIR bandwidth of a frame relay circuit,
the performance of the PVC starts to degrade. Lots of buffered packets will
tend to do the same, so bursts on a point-to-point serial link cause the
same problem.
----- Original Message -----
From: "David Chandler"
To:
Sent: Thursday, April 26, 2001 1:05 PM
Subject: Utilization/load Calculations [7:2167]
> Hi all:
>
> How is the "Load" calculated on a serial interface, or any interface for
> that matter?
>
> Does it:
> 1. Use some weird formula like the 5 minute moving average? dreamed
that thing up?
> 2. Use the greater of the input or output bps?
> 3. Add the current (input + output) bps together and ratio it against
> the max possible (input + output) bps?
> 4. none of the above.
> We often use ciscoview to monitor circuits for error, dropped packets,
> input/output bps etc. (It is a lot better than having to keep refreshing
> your telnet sh int..sh int...sh int..) The utilization which comes from
> the load never really seems to make any sense. For example: if the Tx is
> maxed out the utilization does not indicate it... I gave up looking at
> load/utilization a long time ago. Unfortunately my coworkers seem to
> think that unless the utilization (via Ciscoview) is high that the slow
> response issues have to be caused by something else. Needless to say;
> when the circuit is upgraded and the slow response issues clear, there
> is a lot of political knife sharpening...
>
> TIA
>
> DaveC
>
> PS: I did check archives. After 100+ messages not telling me what I
> wanted to know; decided this was a group Question.
> FAQ, list archives, and subscription info:
http://www.groupstudy.com/list/cisco.html
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