Brocade Fabric OS Administrators Guide (Supporting Fabric OS v7.3.0) - Manual (Page 386)

Limitations and restrictions for QoS zone-based traffic prioritization
• Enabling and disabling QoS is potentially disruptive to the I/O on the affected port.
• If a host and target are included in two or more QoS zones with different priorities, the following
priorities take precedence:
‐ High and medium zones = High priority
‐ High and low zones = Low priority
‐ Medium and low zones = Low priority
‐ High, medium, and low zones = Low priority
For example, if an effective zone configuration has QOSH_z1 (H,T) and QOSL_z2 (H,T), the traffic
flow between H and T will be of low QoS priority.
• If QOSH_z1 (H,T) overlaps with a D,I (domain,index) zone at the H port, the traffic flow between H
and T is dropped to medium priority and the H port is marked as a session-based zoning port.
• Traffic prioritization is enforced on the egress ports only, not on the ingress ports.
• Traffic prioritization is not supported on mirrored ports.
• Traffic prioritization is not supported over LSAN zones. The traffic is always medium priority in the
ingress edge fabric, the backbone fabric, and the egress edge fabric.
• Traffic prioritization is not supported on a CryptoTarget container (redirection zone). Refer to the
Fabric OS Encryption Administrator's Guide for information about redirection zones.
• Traffic prioritization is not supported in McDATA Fabric Mode (interopmode 2) or Open Fabric Mode
(interopmode 3).
• QoS zones that use D,I notation are not supported for QoS over FCR.
• QoS zones that use D,I notation should not be used for loop or NPIV ports.
• If QoS is enabled, an additional 16 buffer credits are allocated per port for 8-Gbps ports in Extended
Mode (LE). Refer to Managing Long-Distance Fabrics on page 527 for information about buffer
credit allocation in extended fabrics.
• If some ports in a trunk group have QoS enabled and some ports have QoS disabled, then two
different trunks are formed, one with QoS enabled and one with QoS disabled.
• QoS mode cannot be explicitly enabled on simulation ports (SIM ports). CS_CTL mode can be
enabled on SIM ports.
Setting QoS zone-based traffic prioritization
1. Connect to the switch and log in using an account with admin permissions.
2. Enter the zoneCreate command to create zones for high- and low-priority traffic.
• For high-priority traffic, use the following syntax:
zonecreate "QOSHid_zonename", "member[; member...]"
• For low-priority traffic, use the following syntax:
zonecreate "QOSLid_zonename", "member[; member...]"
The id range is from 1 through 5 for high-priority traffic, which corresponds to VCs 10 through 14.
For low-priority traffic, the id range is from 1 through 2, which corresponds to VCs 8 and 9. The id is
optional; if it is not specified, the virtual channels are allocated by means of a round-robin scheme.
3. Enter the cfgAdd command to add the QoS zone to the zone configuration, by using the following
syntax:
cfgadd "cfgname", "QOSzonename"
4. Enter the cfgSave command to save the change to the defined configuration.
Limitations and restrictions for QoS zone-based traffic prioritization
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