Using Pfc And Ets To Manage Converged Ethernet Traffic; Hierarchical Scheduling In Ets Output Policies - Dell C9000 Series Networking Configuration Manual

Using PFC and ETS to Manage Converged
Ethernet Traffic

Using PFC and ETS to manage converged ethernet traffic:

dcb-map linecard all backplane all dcb-map-name

Hierarchical Scheduling in ETS Output Policies

ETS supports up to three levels of hierarchical scheduling.
For example, you can apply ETS output policies with the following configurations:
Priority group 1 Assigns traffic to one priority queue with 20% of the link bandwidth and strict-priority
scheduling.
Priority group 2 Assigns traffic to one priority queue with 30% of the link bandwidth.
Priority group 3 Assigns traffic to two priority queues with 50% of the link bandwidth and strict-priority
scheduling.
In this example, the configured ETS bandwidth allocation and scheduler behavior is as follows:
Therefore, in this example, scheduling traffic to priority group 1 (mapped to one strict-priority queue) takes
precedence over scheduling traffic to priority group 3 (mapped to two strict-priority queues).
Unused bandwidth Normally, if there is no traffic or unused bandwidth for a priority group, the bandwidth
usage: allocated to the group is distributed to the other priority groups according to the
bandwidth percentage allocated to each group. However, when three priority groups
with different bandwidth allocations are used on an interface:
Strict-priority If two priority groups have strict-priority scheduling, traffic assigned from the priority
groups: group with the higher priority-queue number is scheduled first. However, when three
priority groups are used and two groups have strict-priority scheduling (such as groups
1 and 3 in the example), the strict priority group whose traffic is mapped to one queue
takes precedence over the strict priority group whose traffic is mapped to two queues.
• If priority group 3 has free bandwidth, it is distributed as follows: 20% of the free
bandwidth to priority group 1 and 30% of the free bandwidth to priority group 2.
• If priority group 1 or 2 has free bandwidth, (20 + 30)% of the free bandwidth is
distributed to priority group 3. Priority groups 1 and 2 retain whatever free
bandwidth remains up to the (20+ 30)%.
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