Cisco N5010P-N2K-BE, Software Configuration Manual

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Cisco Nexus 5000 Series Switch CLI Software Configuration Guide
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Chapter 31 Configuring QoS
Information About QoS
Ingress Policies
You can associate an ingress policy map with an Ethernet interface, to guarantee bandwidth for the
specified traffic class or to specify a priority queue.
The ingress policy is applied in the adapter to all outgoing traffic that matches the specified CoS value.
When you configure an ingress policy for an interface, the switch sends the configuration data to the
adapter. If the adapter does not support DCBX protocol (or the ingress policy TLVs), the ingress policy
configuration is ignored.
Egress Policies
You can associate an egress policy map with an Ethernet interface, to guarantee the bandwidth for the
specified traffic class or to configure the egress queues.
The bandwidth allocation limit applies to all traffic on the interface (including any FCoE traffic).
Each Ethernet interface supports up to eight queues (one for each system class). The queues have the
following default configuration:
• Queue zero is configured as a strict priority queue. Control traffic destined for the CPU uses this
queue.
•
FCoE traffic (traffic that maps to the FCoE system class) is assigned a queue. This queue uses WRR
scheduling with 50 percent of the bandwidth.
• Standard Ethernet traffic (in the default drop system class) is assigned a queue. This queue uses
WRR scheduling with 50 percent of the bandwidth.
If you add a system class, a queue is assigned to the class. You must reconfigure the bandwidth allocation
on all affected interfaces. Bandwidth is not dedicated automatically to user-defined system classes.
You can configure an additional strict priority queue. This queue is serviced before all other queues
except queue zero (which carries control traffic, not data traffic).
QoS for Multicast Traffic
The system provides six multicast queues per interface and allocates one queue for each system class.
By default, all multicast Ethernet traffic is classified into the default drop system class. This traffic is
serviced by one multicast queue.
The optimized multicast feature allows use of the unused multicast queues, to achieve better throughput
for multicast frames. If optimized multicast is enabled for the default drop system class, the system will
use all six queues to service the multicast traffic (all six queues are given equal priority).
If you define a new system class. a dedicated multicast queue is assigned for this class. This queue is
removed from the set of queues available for optimized multicast.
The optimized multicast feature achieves better throughput for multicast frames and improves
performance for multicast frames.
Note Optimized multicast is supported on the BF and later versions of the Cisco Nexus 5020 switch. To verify
the model version, enter the
show module 1 command. The model version is the last two characters of
the model number. Optimized multicast is supported on all versions of the Cisco Nexus 5010 switch.