Cisco 7401ASR Installation And Configuration Manual page 106

PXF Troubleshooting Information
No Buffers
If there are too many buffers configured for the output hold queue on an interface, this can use memory
and result in dropped input packets. Enter the show running-config command and the show interfaces
command to display the status of the incoming packet interfaces.
Priority and Policing Configured in the Class Policy
PXF does not support a configured priority and policing in the same class of a policy.
PXF Punts
If a feature that is supported in the PXF path appears not to be working, it could be the result of PXF
failing to punt packets when it should. If you have only particular interfaces running the feature, you can
configure a feature that PXF does not support on that interface to force PXF to punt packets.
QoS Fast-send and QoS Enqueue
PXF is responsible for managing the outbound traffic queues on an interface on which output QoS
queueing is configured. All traffic destined for this interface must be processed by PXF, including both
keepalive packets that originate in the router, known as QoS Fast-send packets, and packets that are
switched in IOS, known as QoS Enqueue packets. If there is excessive traffic on the QoS Enqueue or on
the QoS Fast-send path, QoS functionality can be disrupted. Use the show pxf accounting summary
command to display the QoS Fast-send and QoS Enqueue packets:
Router# show pxf accounting summary
.
.
.
qos fastsend:
qos enqueue:
WFQ Queues
When there is an increase in ignored packets and in the no buffer count, it is possible that the output
weighted fair queueing (WFQ) queues are too long. To specify the number of dynamic queues to be
reserved for use by the class-default class as part of the default class policy, use the fair-queue
policy-map class configuration command; for example:
Router# fair-queue
policy-map policy9
class class-default
fair-queue 16
queue-limit 20
Cisco 7401ASR Installation and Configuration Guide
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Chapter 5 Troubleshooting
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