Egress Queuing - Cisco Nexus 7000 Series Configuration Manual

Egress Queuing

Egress Queuing
You use egress queuing to determine how to schedule the traffic from the egress queues out of a port. The
class map names represent queues and match cos represents the CoS values mapped to them. You can modify
the egress class map and match cos to achieve the desired CoS-to-queue mapping.
Note CoS remapping is supported only in strict F-Series VDCs. It is not supported in F-Series/M1 mixed VDCs.
Each egress port has about 0.7 MB of buffers that are distributed equally among the 8 CoS values. A CoS has
approximately 0.1 MB of buffers.
The default policy egress queues are created as follows:
• The drop and no-drop CoS must be mapped to different queues.
• The priority CoS is mapped to a strict priority (SP) queue. All the nonpriority CoS values are mapped
• For all the non-8e templates, second level scheduling is used.
Note
• Egress queues have a fixed size and are not user configurable.
• The egress port has four queues, except for the Cisco Nexus 7710 switch and the Cisco Nexus 7718
Each network qos policy has a corresponding default egress queuing policy (template) and is automatically
activated for the system. They are the default-4q-8e-out-policy, default-4q-7e-out-policy,
default-4q-6e-out-policy, default-4q-4e-out-policy, default-8e-4q8q-out-policy, default-7e-4q8q-out-policy,
default-6e-4q8q-out-policy, default-4e-4q8q-out-policy and the default-8e-4q4q-out-policy. The flexible
egress queues configuration is based on these queue types— 1p7qlt-8e, 1p7qlt-7e, 1p3q1t-8e, 1p3q1t-7e,
2p2q1t-4e, 2p6q1t-4e, 3p1q1t-6e, and 3p5qlt-6e.
For the Cisco Nexus 7710 switch and the Cisco Nexus 7718 switch, a hierarchical scheduling pattern is
followed on the 7e-4q8q, 6e-4q8q, and 4e-4q8q templates.
The predefined class map names (queue names) for egress queuing are described in the table below.
Table 35: Predefined Class Maps for Egress Queuing
Egress Policy Names
default-4q-8e-out-policy
default-4q-7e-out-policy
default-4q-6e-out-policy
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to a DWRR queue.
switch, whereby, beginning with Cisco Release 6.2(2), has support for eight queues (4q8q mode).
Configuring Queuing and Scheduling on F-Series I/O Modules
Egress Class Map Names
1p3q1t-8e-out-pq1, 1p3q1t-8e-out-q2,
1p3q1t-8e-out-q3, and 1p3q1t-8e-out-q-default
1p3q1t-7e-out-pq1, 1p3q1t-7e-out-q2,
1p3q1t-7e-out-q3, and 1p3q1t-7e-out-q-default
3p1q1t-6e-out-pq1, 3p1q1t-6e-out-pq2,
3p1q1t-6e-out-pq3, and 3p1q1t-6e-out-q-default