Qlogic 8400 Series, User Manual

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12–NIC Partitioning and Bandwidth Management
Configuration Parameters
253 83840-546-00 D

It is possible for the sum of all maximum bandwidth values across the four
functions of a single port to exceed the physical link speed value of either 10
Gbps or 1 Gbps. This case is called oversubscription. In a case where
oversubscription congestion occurs on transmit, the
Relative Bandwidth
Weight value comes into effect.

The Maximum Bandwidth setting is only valid in the context of Tx, but not
Rx.
An example configuration:
Four functions (or partitions) are configured with a total of six protocols, as shown
below.
Function 0

Ethernet

FCoE
Function 1

Ethernet
Function 2

Ethernet
Function 3

Ethernet

iSCSI
1. If Relative Bandwidth Weight is configured as “0” for all four PFs, then all
six offloads will share the bandwidth equally. In this case, each offload will be
assigned roughly 16.67% of the total bandwidth.
2. If Relative Bandwidth Weight is configured as “25” for all four PFs, then
Ethernet and FCoE offloads on function 0 and Ethernet and iSCSI offloads
on function 3 will be assigned roughly 12.5% of the total bandwidth, whereas
Ethernet offloads on function 1 and function 2 are assigned roughly 25% of
the total bandwidth.