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Getting packet drop due to QOS on cisco ASR1001

dhanamjay
Level 1
Level 1

Hello Team,

 

For Management Purpose we have dedicated connectivity with 500 kbps BW.

 

piad806#sh run int g0/0/1.100
Building configuration...

Current configuration : 298 bytes
!
interface GigabitEthernet0/0/1.100
description --- To biad915 - TE2/1/0.100 - IP BW 500
bandwidth 500
encapsulation dot1Q 100
ip vrf forwarding xxx-remote-mgmt
ip address X.X.X.X 255.255.255.252
service-policy input COUNT-IN
service-policy output SILVER-OUT-SHAPED-Gi0/0/1.100
end

 

piad806#sh run policy-map SILVER-OUT-SHAPED-Gi0/0/1.100
Building configuration...

Current configuration : 192 bytes
!
policy-map SILVER-OUT-SHAPED-Gi0/0/1.100
class class-default
shape average 464000
police 16000 8000 8000 conform-action set-prec-transmit 2 exceed-action set-prec-transmit 2
!
end

 

As per  my understanding if this interface is getting more that specified traffic means it should keep them in queue and later it need to process them, but the excess traffic is getting dropped.

 

Can anyone explain me why its happening like this, and also what is offered rate, drop rate. is this applicable for traffic before processing by policy-map or after processing.

 

piad806#sh policy-map interface g0/0/1.100 output
GigabitEthernet0/0/1.100

Service-policy output: SILVER-OUT-SHAPED-Gi0/0/1.100

Class-map: class-default (match-any)
8010003 packets, 5806869365 bytes
30 second offered rate 1087000 bps, drop rate 623000 bps
Match: any
Queueing
queue limit 64 packets
(queue depth/total drops/no-buffer drops) 61/4799500/0
(pkts output/bytes output) 3211728/2223284892
shape (average) cir 464000, bc 1856, be 1856
target shape rate 464000
police:
cir 16000 bps, bc 8000 bytes, be 8000 bytes
conformed 169194 packets, 75983637 bytes; actions:
set-prec-transmit 2
exceeded 166 packets, 100028 bytes; actions:
set-prec-transmit 2
violated 7841868 packets, 5731659850 bytes; actions:
set-prec-transmit 2
conformed 15000 bps, exceeded 0000 bps, violated 1071000 bps
piad806#

 

Regards,

Dhanamjay.

3 Replies 3

Hello,

 

your shaping and policing rates look extremely low:

 

shape average 464000 --> this equals about .5 Mbit

 

police 16000 --> this is .16 Mbit

 

 

 

 

Hello Georg,

Thanks for looking into it, yes is for just Mgmt traffic purpose only and for that we allocated 0.5 Mbps BW.

Can you explain me why we are getting drop, i guess excess traffic need to keep in queue and then process right as per this policy map. but still why we are getting drop.

and also what is offered rate, drop rate. is this applicable for traffic before processing by policy-map or after processing.

Hello,

 

I am not sure what happens when you use a shaper and a policer in the same policy. You might want to try a policy with just one or the other:

 

policy-map SILVER-OUT-SHAPED-Gi0/0/1.100
class class-default
shape average 464000

or

 

policy-map SILVER-OUT-SHAPED-Gi0/0/1.100
class class-default
police 16000 8000 8000 conform-action set-prec-transmit 2 exceed-action set-prec-transmit 2

 

Also, in the policer, try and add the 'violate-action', as this changes the token bucket from a one to a two system bucket...