| Description | The current bandwidth consumed. The measurement unit is
in megabits per second (1,000,000 bits/second).
This value gives a reasonable estimate of the amount of
traffic currently flowing through the switch.
It is calculated as follows:
Octets*8 + Frames*(96 + 64)
---------------------------
Measurement Interval * 1,000,000 * 2
Where:
Measurement Interval is the amount of time over which
the Octets and Frames were collected, in seconds.
Measurement Interval is always one second in current
implementation.
Octets is the total number of octets transmitted
or received by all network interfaces, excluding
framing data but including FCS. This includes octets
in frames which were partially transmitted or
received (due to collisions, for example).
Frames is the total number of frames transmitted
or received by all network interfaces, including
frames with errors.
The number of frames is multiplied by 96 plus 64 in
order to estimate the delay between each frame for
Ethernet's IPG and preamble/SFD.
The '2' in the divisor makes this a forwarding bandwidth
counter. A frame received on one interface is typically
forwarded out another interface. In order to avoid double-
counting this frame's bandwidth, once on the receiving
interface and once on the transmitting interface, the
total bandwidth is divided by two.
Since multicast and broadcast frames can be sent to multiple
ports, the above is at best a lower bound. |