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Beginner

NCS 5501-SE QOS

Ok - I'm trying to get a egress policy to work on a NCS 5501-SE

Get this error, been reading the documentation- not quite sure what is going on.

NCS is on 6.2.25

 

 

 

Error:

RP/0/RP0/CPU0:XXX(config)#int te0/0/0/0
RP/0/RP0/CPU0:XXX(config-if)#service-policy output TX-QOS-10Gbit
RP/0/RP0/CPU0:XXX(config-if)#commit
..
RP/0/RP0/CPU0:XXX(config-if)#show configuration failed
interface TenGigE0/0/0/0
service-policy output TX-QOS-10Gbit
!!% 'DNX_QOSEA' detected the 'warning' condition 'Invalid egress policy-map configuration. Use qos-group for marking features and traffic-class for queuing features'
!
end

The policy - has been dumbed down from the one we usually use on a ASR9k - first thing 

policy-map TX-QOS-10Gbit
 class 10Gbit_Q8
  priority level 1
  police rate percent 10
  !
 !
 class 10Gbit_Q7
  priority level 2
  police rate percent 10
  !
 !
 class 10Gbit_Q6
  bandwidth remaining percent 8
 !
 class 10Gbit_Q5
  bandwidth remaining percent 10
 !
 class 10Gbit_Q4
  bandwidth remaining percent 10
 
 class 10Gbit_Q3
  !
  random-detect default
  bandwidth remaining percent 10
 !
 class 10Gbit_Q2
  !
  bandwidth remaining percent 2
  random-detect default
 !
 class class-default
  random-detect default
  bandwidth remaining percent 40
 !
 end-policy-map

Classes:

class-map match-any 10Gbit_Q2
 match qos-group 1
 end-class-map
!
class-map match-any 10Gbit_Q3
 match qos-group 2
 end-class-map
!
class-map match-any 10Gbit_Q4
 match qos-group 3
 end-class-map
!
class-map match-any 10Gbit_Q5
 match qos-group 4
 end-class-map
!
class-map match-any 10Gbit_Q6
 match qos-group 7
 end-class-map
!
class-map match-any 10Gbit_Q7
 match qos-group 6
 end-class-map
!
class-map match-any 10Gbit_Q8
 match qos-group 5
 end-class-map

Any ideas ?

7 REPLIES 7
Cisco Employee

Re: NCS 5501-SE QOS

Hi Benedikt,

 

since IOS-XR 6.1.2 on NCS5500 we are using match on qos-group for egress (re)marking actions. For queue selection and corresponding actions  we are using traffic-class.

If you change your class-maps to match on traffic-class the service-policy  will be accepted. Please note you need to adapt your ingress policy accordingly to set traffic-class instead of qos-group.

If you need both, queuing actions and remark we allow to apply two service-policies on egress. 

Please also note policing is not supported in egress direction.  You can use a shaper instead. If you need low latency queuing in the shaped queue you can set queue-limit to a low value like 500us. 

 

Regards Frank

Beginner

Re: NCS 5501-SE QOS

I don't quite get the point of below:
" If you need low latency queuing in the shaped queue you can set queue-limit to a low value like 500us".
In my understanding queue length only impact on latency in case of congestion happens. But normally it should not congest for those queues. Does it mean there is no mechanism to let packet scheduled in NCS5500 without entering buffer?
Thanks
Br
Tim
Highlighted
Cisco Employee

Re: NCS 5501-SE QOS

Tim,

No queuing unless there is congestion. Frank is saying if there is congestion and you want LLQ, keep shallow queues.

Beginner

Re: NCS 5501-SE QOS

>From my experience on asr 9000, packet need to enter buffer to schedule in
TM, even no congestion, but will be scheduled out very fast if it has a
high priority. But this introduce some delay. But there is llq mode to
allow packet scheduled out without entering buffer at all. Does this logic
suit for ncs also? Thanks
Cisco Employee

Re: NCS 5501-SE QOS

Sorry I couldn't follow the logic, even if llq is configured and no congestion, no delay.
Beginner

Re: NCS 5501-SE QOS

My point is no llq, congestion happened with low priority, lentency of high
priority traffic will be impacted
Cisco Employee

Re: NCS 5501-SE QOS

if there is congestion in the LP queue it has no effect on the HP queue.
On NCS5500 we can't use a policer on egress. Alternatively you can use a shaper. If you have a shaper configured and this specific queue needs low latency it is recommended to decrease the queue-limit to a very low value. 

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