kritchie@bear.blake.pvt.k12.mn.us (Kent Ritchie) said:
Kent> I have been experimenting with the SNMP Monitor
Kent> module... specifically the Interface Load feature. I have
Kent> been monitoring my routers and bridges, and I am
Kent> curious... when it lists a percentage, it is showing a
Kent> percentge of the rated bandwidth of the interface right? I
Kent> have Serial 0 and Ethernet 0 on my router and Serial 0 is
Kent> connected to 1.54Mb FR and the Ethernet 0 is connected to 10Mb
Kent> ethernet. If I see 12.97% on Serial 0 I am using 12.97% of
Kent> 1.54Mb? or am I using 12.97% of Serial 0's maximum bandwidth
Kent> (not sure what that is...)?
I don't know if the maximum bandwidth of a FR (Frame Relay?) interface
is different from 1.54Mb per second. Below is the comment from the
sources which explains what the Interface Load command calculates.
##
## Calculate the interface utilisation. This is done using the 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 should be 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.
##
Please read the article in the Simple Times for more details. The
formula is usually known as Leinwand's formula. I just added this
text to the help text of the snmp_monitor.tcl script.
Juergen