Mark J. Elkins <mje@posix.co.za> said:
mje> What does the SNMP Load strip chart actually show? I've been
mje> monitoring two sides of the same line and the value is about
mje> the same. On a very heavy loaded line (ISP's link to the
mje> Internet) - the value stops at just over 98%.. and not 100%
mje> ???
The answer is in the "HELP SNMP-Monitor" entry of the SNMP-Monitor
menu:
Interface Load:
Compute the load of an interface and display it in a stripchart.
The load is calculated using Leinwand's formula:
util = ( 8 * ( delta (ifInOctets, t1, t0)
+ delta (ifOutOctets, t1, t0) ) / (t1 - t0) ) / ifSpeed
This formula returns incorrect results for full-duplex point
to point links. In this case, the following formula is used:
util = ( 8 * max ( delta (ifInOctets, t1, t0) ,
delta (ifOutOctets, t1, t0) ) / (t1 - t0) ) / ifSpeed
See Simple Times 1(5), November/December, 1992 for more details.
The interface speed is usually retrieved from MIB-II but you can
overwrite it by setting the SNMP-Monitor:IfSpeed attribute.
mje> If I had written the software - I think I would show the load
mje> of the highest direction. that is - if the incoming load is
mje> 50% and the outgoing load is 80% - then show 80% as the
mje> load... Is this what happens? Is it possible to see what the
mje> load in the other direction is?
You should see the load of the highest direction. You can not see
the other load right now (but it should be easy to modify the
snmp_monitor.tcl script). Regarding the `98%.. and not 100%'
percent question, please calculate the load by hand using the
interface statistics and let me know if you get different results
(perhaps due to some rounding errors in the Scotty script).
Juergen