Folks,
The "Set Link Speed..." window helps InterMapper compute link utilization. (It
obviously does not change the speed or duplex setting of the real interface.)
This window has settings for the expected transmit and receive speeds for the
link so you can _override_ the ifSpeed reported by the interface.
Example: Let's say you have a 100 mbps interface on your router going into an
assymetric DSL link with a max of 16mbps download and 2 mbps upload. It's useful
to compute utilization separately for each direction based on those speeds, not
100 mbps of the actual interface. Setting those speeds in the "Set Link Speed..."
window will do this.
InterMapper has a single number for the utilization of an interface. It always
reports the highest utilization on the interface. There are two cases:
a) If you have checked "Full duplex", InterMapper computes the actual transmit/receive
rates as a percentage of the customer-entered rates, and then reports the larger
percentage. Thus if the DSL link above is receiving and sending 1.0 mbps in each
direction simultaneously, InterMapper will calculate the transmit utilization
as 50% and the receive utilization as 6.25%, and show the link as 50% used.
b) If you have checked "Baseband", InterMapper adds the transmit and receive data
rates to calculate the utilization. Thus a 10BaseT (half-duplex) link that's transmitting
3 mbps and receiving 3 mbps would be shown with a utilization of 60%. (3 mbps
+ 3 mpbs = 6 mbps = 60% of a 10 mbps interface.)
There's also information about the link speed and duplex setting saved in the
InterMapper Database. I'll send another note soon with definitive information
(and sql queries) that can be used to check that information.
Rich Brown [email protected]
Dartware, LLC http://www.dartware.com
66-7 Benning Street Telephone: 603-643-9600
West Lebanon, NH 03784-3407 Fax: 603-643-2289
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