Brocade Fabric OS Administrators Guide (Supporting Fabric OS v7.3.0) - Manual (Page 381)

QoS zone-based traffic prioritization
QoS zone-based traffic prioritization allows you to categorize the traffic flow between a host and a target
as having a high, medium, or low priority, depending on the type of zone.
High-, medium-, and low-priority flows are allocated to different virtual channels (VCs). High-priority
flows receive more fabric resources than medium-priority flows, which receive more resources than low-
priority flows.
For example, you could assign online transaction processing (OLTP) to high priority and backup traffic
to low priority.
All flows without QoS prioritization are considered medium priority.
NOTE
If there is a single low-priority flow to a destination ID (DID) and several medium-priority flows to that
same DID, then it is possible that the medium-priority flows would have less bandwidth. This is because
they have to share the medium-priority fabric resources, whereas the low-priority flow would have a
separate set of fabric resources for its exclusive use.
For new switches, QoS mode is automatically enabled on the E_Ports, except for long-distance
E_Ports. For long-distance E_Ports, you must manually enable QoS mode.
If you upgrade to Fabric OS 7.2.0 or later from Fabric OS 7.1.x or earlier, and you did not previously
have an Adaptive Networking license, then all ports that had QoS mode set to AE (automatically
enabled) and were not using the QoS feature are automatically set to OFF after the upgrade. You must
manually configure these ports for QoS.
QoS zones
You assign high, medium, or low priority (QoS level) by configuring a QoS zone . A QoS zone is a
special zone that indicates the priority of the traffic flow between a given host/target pair. By default,
traffic in non-QoS zones is treated as medium priority.
The members of a QoS zone are the host/target pairs. QoS zones can contain WWN members (WWNN
or WWPN) or domain,index (D,I) members. If you use D,I notation in your QoS zones, refer to
Limitations and restrictions for QoS zone-based traffic prioritization on page 386 for some
considerations.
A QoS zone has a special name to differentiate it from a regular zone. The name of the zone
determines the priority of the traffic flow. The format of the QoS zone name is as follows:
For high priority: QOSHid_xxxxx
For medium priority: QOSMid_xxxxx
For low priority: QOSLid_xxxxx
In the QoS zone name format, id is a flow identifier that designates a specific virtual channel (VC) for
the traffic flow and xxxxx is the user-defined portion of the name. For example, the following are valid
QoS zone names:
QOSH3_HighPriorityTraffic
QOSL1_LowPriorityZone
QoS zone-based traffic prioritization
Fabric OS Administrators Guide 381
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