CBWFQ Shaping and Policing

[lunar_rover]

Hi.

I have a router running IOS-XE terminating a 300Mbps transatlantic WAN link.

I have written the following policy to be applied to the outgoing interface facing the WAN:

policy-map 300MBPS-SHAPER
 class class-default
  shape average 300000000
   service-policy UK-US-LOG-LIMITER

policy-map UK-US-LOG-LIMITER
 class US-LOG-DESTS
  police cir percent 33
 class class-default
  bandwidth remaining percent 100

class-map match-any US-LOG-DESTS
 match access-group name NACL-US-LOG-DESTS

ip access-list extended NACL-US-LOG-DESTS
 remark MATCH-US-LOGGING-ENDPOINTS
 permit ip any host x.x.x.x

The intention being to shape all the outbound traffic to 300M, and within that, limit logging traffic to a maximum of 1/3rd of the bandwidth i.e. 100M, and let everything else use all of the remaining bandwidth (including any of the 100M logging traffic is not using in any time interval).

When the configuration is applied I still see logging traffic saturating the link - I'd appreciate any thoughts on how I've misconfigured this!

[Samer R. Saleem]

Hi,
Why you are using #police cir percent 33 ?
Why not using #police cir 100 m
I think would take 33 % from the interface bandwidth, which is 1 Gbps

[lunar_rover]

Good question - I thought the outer policy map being shaped to 300M meant the inner policy map parameters worked within the confines of 300M, is that not how it works?

[a.alekseev]

show policy-map interface XXX

[paul driver · Accepted solution]

Hello

My understanding is it preferred to use policing for ingress traffic and shaping for egress traffic.

Suggest if you want to prioritize some traffic then use LLQ which would provide a maximum defined traffic BW allocation under times of congestion but it wont stave the other class whilst doing so.

As for the remaining traffic this would fall into the class class-default class which has a default queuing of FIFO but you can change this so to apply some degree of fairness for your remaining non specified qos traffic when exiting the wan interface.

policy-map UK-US-LOG-LIMITER
class US-LOG-DESTS
priority percent 33
class class-default
fair-queue