Traffic not queued or prioritized correctly on Nexus 2148, Nexus 2232, and Nexus 2248

Traffic not queued or prioritized correctly on Nexus 2148, Nexus 2232, and Nexus 2248

After configuring all three types of policy maps (QoS, Network-QoS, and Queuing), the traffic is not queued or prioritized correctly on Nexus 2148, Nexus 2232, and Nexus 2248 switches.

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Possible Cause
The Nexus 2148, Nexus 2232, and Nexus 2248 FEX can only support CoS-based traffic classification. The QoS service policy type configured under System QoS is populated from the Nexus 5000 to FEX only when all the matching criteria are match cos. If other match clauses exist, such as match dscp or match ip access-group in the QoS policy map, then the FEX does not accept the service policy. As a result, all the traffic is placed into the default queue

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Solution
For the ingress traffic (from server to network) that is not marked with a CoS value, the traffic is placed into the default queue on FEX. Once the traffic is received on the Nexus 5000, it is classified based on a configured rule and are placed in the proper queue.
For the egress traffic (from Nexus 5000 to FEX, and then FEX to server), it is recommended that you mark mark the traffic with a CoS value on the Nexus 5000 so that the FEX can classify and queue the traffic properly.
The following example is a complete Nexus 5000 and Nexus 2232/Nexus 2248 configuration that classifies the traffic and configures the proper bandwidth for each type of traffic. This example applies only to the Nexus 5000 and Nexus 2248. The configuration for the Nexus 2148 is slightly different due to the fact that Nexus 2148 has only two queues for user data. The Nexus 2232/Nexus 2248 has six hardware queues for user data, which is the same as Nexus 5000.

Example:
//class-map for global qos policy-map, which will be used to create CoS-queue mapping.//
class-map type qos voice-global
match cos 5
class-map type qos critical-global
match cos 6
class-map type qos scavenger-global
match cos 1
class-map type qos video-signal-global
match cos 4
//This qos policy-map will be attached under “system qos”. It will be downloaded to 2248 to create CoS to queue mapping.//
policy-map type qos classify-5020-global
class voice-global
set qos-group 5
class video-signal-global
set qos-group 4
class critical-global
set qos-group 3
class scavenger-global
set qos-group 2
class-map type qos Video
match dscp 34
class-map type qos Voice
match dscp 40,46
class-map type qos Control
match dscp 48,56
class-map type qos BulkData
match dscp 10
class-map type qos Scavenger
match dscp 8
class-map type qos Signalling
match dscp 24,26
class-map type qos CriticalData
match dscp 18
//This qos policy-map will be applied under all N5k and 2248 interfaces to classify all incoming traffic based on DSCP marking. Please note that even the policy-map will be applied under Nexus 2248 interfaces the traffic will be classified on N5k//
policy-map type qos Classify-5020
class Voice
set qos-group 5
class CriticalData
set qos-group 3
class Control
set qos-group 3
class Video
set qos-group 4
class Signalling
set qos-group 4
class Scavenger
set qos-group 2
class-map type network-qos Voice
match qos-group 5
class-map type network-qos Critical
match qos-group 3
class-map type network-qos Scavenger
match qos-group 2
class-map type network-qos Video-Signalling
match qos-group 4
//This policy-map type network-qos will be applied under “system qos” to define the MTU, marking and queue-limit(not configured here).//
policy-map type network-qos NetworkQoS-5020
class type network-qos Voice
set cos 5
class type network-qos Video-Signalling
set cos 4
mtu 9216
class type network-qos Scavenger
set cos 1
mtu 9216
class type network-qos Critical
set cos 6
mtu 9216
class type network-qos class-default
mtu 9216
class-map type queuing Voice
match qos-group 5
class-map type queuing Critical
match qos-group 3
class-map type queuing Scavenger
match qos-group 2
class-map type queuing Video-Signalling
match qos-group 4

//The queuing interface will be applied under “system qos” to define the priority queue and how bandwidth is shared among non-priority queues.//

policy-map type queuing Queue-5020
class type queuing Scavenger
bandwidth percent 1
class type queuing Voice
priority
class type queuing Critical
bandwidth percent 6
class type queuing Video-Signalling
bandwidth percent 20
class type queuing class-fcoe
bandwidth percent 0
class type queuing class-default
bandwidth percent 73

//The input queuing policy determines how bandwidth are shared for FEX uplink in the direction from FEX to N5k. The output queueing policy determines the bandwidth allocation for both N5k interfaces and FEX host interfaces.//

system qos
service-policy type qos input classify-5020-global
service-policy type network-qos NetworkQoS-5020
service-policy type queuing input Queue-5020
service-policy type queuing output Queue-5020

//Apply service-policy type qos under physical interface in order to classify traffic based on DSCP. Please note that for portchannel member the service-policy needs to be configured under interface port-channel.//

interface eth1/1-40
service-policy type qos input Classify-5020
interface eth100/1/1-48
service-policy type qos input Classify-5020

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