Scheduling traffic for forwarding – Brocade Multi-Service IronWare QoS and Traffic Management Configuration Guide (Supporting R05.6.00) User Manual
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Multi-Service IronWare QoS and Traffic Management Configuration Guide
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Hierarchical QoS (HQoS) for 8x10G modules
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Level 3: The Service level provides the scheduler/shaper for individual customer services, e.g.,
VLAN. The SLA applied here would apply to the individual service for that customer. For
example, a customer may have two distinct point-to-point services identified by a SVLAN
sharing the same physical link to the customer. The Service level schedules traffic from
individual priority levels for a particular SVLAN. Priority levels may be served in Strict Priority
(SP), Round Robin (RR), Fair Queuing (FQ), Weighted Round Robin (WRR), or mixed scheduling
schemes.
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Level 2: The Customer level provides the scheduler/shaper for the aggregated services of a
customer. For example, if a customer has two VLAN services at Level 3, this level would provide
for scheduling/shaping of the combined traffic of the two customer VLANs. VLANs of a same
customer are commonly served in Round Robin (RR), Fair Queuing (FQ), or Weighted Round
Robin (WRR) mode.
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Level 1: The Logical Port level provides schedulers/shapers for the traffic that would flow
through the egress port of a downstream device. This level allows for scheduling and shaping
of traffic to fit a downstream port. Customer scheduler flows are commonly served in Round
Robin (RR), Fair Queuing (FQ), or Weighted Round Robin (WRR) mode.
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Level 0: The Physical Port level provides a scheduler/shaper for the egress port. The Physical
Port level schedules traffic from individual Logical Port scheduler flows. Logical Port scheduler
flows are commonly served in Round Robin (RR), Fair Queuing (FQ), or Weighted Round Robin
(WRR) mode.
Scheduling traffic for forwarding
If the traffic being processed by a Brocade device is within the capacity of the device, all traffic is
forwarded as received. Once it reaches the point where the device is bandwidth constrained, it
becomes subject to drop priority if configured.
The Brocade devices classify packets into one of eight internal priorities. Traffic scheduling allows
you to selectively forward traffic according to one of the following schemes:
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Strict priority-based scheduling – This scheme guarantees that higher-priority traffic is always
serviced before lower priority traffic. The disadvantage of strict priority-based scheduling is
that lower-priority traffic can be starved.
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WFQ weight-based traffic scheduling – This scheme services different traffic priorities based
on defined weights. Available bandwidth is divided among the different traffic priorities
proportionally to the defined weights. For example, two priority levels with a same assigned
weight will be served with about the same bandwidth. A priority level with a weight value twice
the weight value of another priority level will be served at about twice the bandwidth of the
other priority level.
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Mixed strict priority and weight-based scheduling – This scheme provides a mixture of strict
priority for the three highest priority with levels and WFQ for the remaining priority levels.
For additional information on configuring QoS, refer to
“Configuring Quality of Service for the
Brocade NetIron XMR and Brocade MLX series”
For examples of queue schedulers for HQoS, refer to