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Default qos class was dropping packet

Hi there,

I have configured the qos below on my cisco 7609 router:

class-map match-any REALTIME

match mpls experimental topmost 5

match precedence 5

match ip dscp cs3 ef

class-map match-any CONTROL

match mpls experimental topmost 6 7

match precedence 6 7

match ip dscp cs6 cs7

class-map match-any Gold

match mpls experimental topmost 4

match precedence 4

match ip dscp cs4 af41 cs6

class-map match-any SILVER

match mpls experimental topmost 1 2

match precedence 1 2

match ip dscp af11 cs2 af21 af31

!

policy-map CORE_Egress

class PE-REALTIME

   priority

   police rate percent 70

     conform-action transmit

     exceed-action drop

class PE-CONTROL

   bandwidth remaining percent 4

class PE-GOLDEN

   bandwidth remaining percent 70

class PE-SILVER

   bandwidth remaining percent 20

class class-default

   bandwidth remaining percent 5

Based on the MRTG graph, my link was peak at 70% and normally it remains below 40%. But, I noticead that my default qos class was dropping packet because the queue-limit was set to 2 packet by deafult. After, changed it to 50 packets, the default was no longer dropping packet.

My question is my link is not congested, but, what caused the queue-depth of 2 packets being overflow until it started to drop packet?

How do I know what kind of incoming traffic speed that will fill up the default queue depth of 2 packets?

1 REPLY
Super Bronze

Default qos class was dropping packet

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Posting

An interface is congested anytime there's a packet waiting.  When an interface is congested, then the question becomes "how congested"?

An interface could be congested at 1% average utilization or not congested at 99% average utilization, i.e. MTRG usage doesn't always indicate whether an interface congests although generally it's more likely as utilization increases.

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