S e n d d o c u m e n t a t i o n c o m m e n t s t o m d s f e e d b a c k - d o c @ c i s c o . c o m
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Cisco MDS 9000 Family CLI Configuration Guide
OL-16184-01, Cisco MDS SAN-OS Release 3.x
Chapter 56 Configuring Fabric Congestion Control and QoS
QoS
A similar occurrence in Switch 2 sends a response to the transaction request. The round trip delay
experienced by the OLTP server is independent of the volume of low priority traffic or the ISL
congestion. The backup traffic uses the available ISL bandwidth when it is not used by the OLTP traffic.
Tip
To achieve this traffic differentiation, be sure to enable FCC (see the
“Enabling FCC” section on
page 56-2
).
VSAN Versus Zone-Based QoS
While you can configure both zone-based QoS and VSAN-based QoS configurations in the same switch,
both configurations have significant differences.
Table 56-1
highlights the differences between
configuring QoS priorities based on VSANs versus zones.
See the
“About Zone-Based Traffic Priority” section on page 23-18
for details on configuring a
zone-based QoS policy.
Configuring Data Traffic
To configure QoS, follow these steps:.
Step 1
Enable the QoS feature.
Step 2
Create and define class maps.
Step 3
Define service policies.
Step 4
Apply the configuration.
Table 56-1
QoS Configuration Differences
VSAN-Based QoS
Zone-Based QoS
If you configure the active zone set on a given
VSAN and also configure QoS parameters in any
of the member zones, you cannot associate the
policy map with the VSAN.
You cannot activate a zone set on a VSAN that
already has a policy map associated.
If the same flow is present in two class maps
associated to a policy map, the QoS value of the
class map attached first takes effect.
If the same flow is present in two zones in a given
zone set with different QoS values, the higher QoS
value is considered.
—
During a zone merge, if the Cisco SAN-OS
software detects a mismatch for the QoS
parameter, the link is isolated.
Takes effect only when QoS is enabled.
Takes effect only when QoS is enabled.
