This depends partly on what version IOS you're running. Earlier versions
(at least up to 11.2) calculate on the outbound traffic only. Inbound
traffic is irrelevant. It is calculated, by default, on a five-minute
weighted 'average' - I don't know the exact algorithm. However you can
change the load interval (the exact command is left as an exercise for the
reader because I don't feel like looking it up - it's an interface command
- but I think it is 'load-interval') so that it is averaged over shorter or
longer periods. The minimum is 30 seconds. If you change this, instead of
a '5 minute input rate' in the show interface output, it will show the
interval that you are using for that interface.
Later versions of IOS (certainly 12.1, not sure when it changed) have
separate figures for txload and rxload.
The load is calculated using the 'bandwidth' statement for the interface.
If your bandwidth isn't set correctly (I think it defaults to 1.5 Mbps for
a serial interface), it won't affect the basic operation of the interface,
but it will affect the accuracy of your load figures (it may also affect
operation of your routing protocol). If you have a 512Kbps line and the
bandwidth has defaulted to 1.5 Mbps, even when you are maxing out your line
your load will only show as about 85/255.
JMcL
---------------------- Forwarded by Jenny Mcleod/NSO/CSDA on 27/04/2001
08:28 am ---------------------------
"David Chandler" @groupstudy.com on 27/04/2001
06:05:29 am
Please respond to "David Chandler"
Sent by: [EMAIL PROTECTED]
To: [EMAIL PROTECTED]
cc:
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? <<<Who
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. <<<this is what I'm betting on..
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.
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