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Improper Configurations
S e n d d o c u m e n t c o m m e n t s t o n e x u s 5 k - d o c f e e d b a c k @ c i s c o . c o m .
Table 4-1
Policy Type
QoS
Queuing
Network-QoS
With the basic process, the incoming packets are compared to the QoS classification rules that are
defined by policy-map type qos. The packets are classified into 1 of 8 qos-groups.
Next, the Network-QoS and Queuing policies are applied to the packets. The Queuing policy and the
Network-QoS policy define actual QoS parameters for packets belonging to each qos-group.
Note
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•
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Improper Configurations
Cannot pass frame size larger than 2300 bytes through switch
Although the jumbo MTU has been configured for class-default, you cannot pass a frame size larger than
2300 bytes through the Nexus 5000 switch and the Nexus 2000 FEX.
Possible Cause
The CoS value may conflict with the existing MTU value.
Solution
CoS 7 is used internally for controlling traffic between the Nexus 5000 switch and the Nexus 2000 FEX.
The MTU value for the traffic with CoS 7 is set to a fixed value. You must check that the incoming traffic
is marked with CoS 7. Use any CoS value other than 7 to avoid this limitation.
Cisco Nexus 5000 Series Troubleshooting Guide
4-2
Types of Policy Maps
Function
Define traffic classification
•
Strict Priority queue
•
Deficit Weight Round Robin
•
•
Define flow control mechanism (PAUSE or
tail drop)
•
MTU per class of service
Queue size
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Marking
•
The Queuing and Network-QoS policies match the qos-group (identified by policy-map type qos)
instead of the actual packet headers.
When the same type of service policy is applied under the System QoS context and the interface
level, the interface level service policy is preferred.
The queuing policy that is applied under the ingress interface is not applied locally. The queueing
policy is the bandwidth allocation for a different class of service that is exchanged with its peer using
the DCBX protocol.
Chapter 4
Troubleshooting QoS Issues
Attach Point
System QoS
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Ingress interface
•
System QoS
•
Egress interface
•
•
Ingress interface
•
System QoS
OL-25300-01
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