nx.os.and.cisco.nexus.switching.2nd.edition.1587143046

class type network-qos class-default
match qos-group 0
mtu 9216
5010-1#
Queuing Policies
The Nexus 5x00 switches support the ability to queue traffic based on classification and
support setting a queue to a strict priority and bandwidth sharing. When configured for strict
priority queuing, all traffic classified into this queue will be serviced before any other
traffic in on the link. The one exception is the default system-defined strict priority queues
for CoS 6 and 7, which are serviced before the user-defined strict priority queue. This is
useful when running a network with requirements for latency-sensitive traffic such as voice
to ensure voice traffic is not delayed in the switch. The primary consideration for using the
strict priority queue is to be careful about what traffic is mapped into the priority queue.
Inadvertently mapping too much traffic into the priority queue can create a situation called
queue starvation. In queue starvation, the strict priority queue constantly has traffic in it that
needs to be serviced and the other queues on the interface do not get access to transmit their
data and in essence starve.
Example 10-22 shows how to define a strict priority queue for voice traffic.
Example 10-22. Defining a Strict Priority Queue
Click here to view code image
5010-1# config
Enter configuration commands, one per line. End with
CNTL/Z.
5010-1(config)# class-map type qos match-all voice
5010-1(config-cmap-qos)# match cos 5
5010-1(config-cmap-qos)# class-map type queuing voice
5010-1(config-cmap-que)# match qos-group 5
5010-1(config-cmap-que)# exit
5010-1(config)# policy-map type queuing voice
5010-1(config-pmap-que)# class type queuing voice
5010-1(config-pmap-c-que)# priority
5010-1(config-pmap-c-que)# system qos
5010-1(config-sys-qos)# service-policy type queuing input
voice
5010-1(config-sys-qos)# show policy-map system type
queuing