526 Fabric OS Administrator’s Guide
53-1002745-02
QoS zones
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The switch automatically sets the priority for the “host,target” pairs specified in the zones
according to the priority level (H or L) in the zone name.
The flow id allows you to have control over the VC assignment and control over balancing the flows
throughout the fabric. The id range is 1–5 for high-priority traffic, which corresponds to VCs 10–14.
For low-priority traffic, the id range is 1–2, 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.
If a QoS zone name prefix is specified in an LSAN zone (a zone beginning with prefix "LSAN_"), the
QoS tag is ignored. Only the first prefix in a zone name is recognized. For example, a zone with the
name "LSAN_QOSH_zone1" is recognized as an LSAN zone and not a QoS zone.
See “QoS over FC routers” on page 527 for additional considerations when using QoS to prioritize
traffic between device pairs in different edge fabrics.
For example, Figure 68 shows a fabric with two hosts (H1, H2) and three targets (S1, S2, S3). The
traffic prioritization is as follows:
• Traffic between H1 and S1 is high priority.
• Traffic between H1 and S3 and between H2 and S3 is low priority.
• All other traffic is medium priority, which is the default.
FIGURE 68 QoS traffic prioritization
For this fabric, you could set up the following QoS zones:
QOSH_Zone1 Members: H1, S1
QOSL_Zone3 Members: H1, H2, S3
QoS on E_Ports
In addition to configuring the hosts and targets in a zone, you must also enable QoS on individual
E_Ports that might carry traffic between the host and target pairs. Path selection between the
“host,target” pairs is governed by FSPF rules and is not affected by QoS priorities. For example, in
Figure 69 QoS should be enabled on the encircled E_Ports.
7
12
3
14
15
16
8
13
Domain 1 Domain 3
Domain 4
Domain 2
H1
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S3
S2
S1
H2
= High priority
= Medium priority
= Low priority
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