09-03-2014 07:02 PM - edited 03-07-2019 08:37 PM
Hello All,
We are troubleshooting a performance issue in our Network. UDP traffic from a particular application is completely congesting the link.
Though we have QoS to throttle the traffic from the application to use only 9% bandwith of the link but that application flodding the traffic around 80% of the link. The traffic from the application is getting categorised as default traffic CS0.
Class class-default
fair-queue
bandwidth remaining 9 (%)
Is there anything we are missing in the configuration of the class-map that is alowing the flodding of the UDP traffic?
Regards,
Thiyagu
09-04-2014 12:47 AM
If you use a router you must configure a policy-map as below (example):
class-map match-any TrafficoVoipCTRL
match protocol skinny
match access-group name TrafficoVoiceCtrl
match access-group name TrafficoICM
match protocol sip
policy-map QosIdcToTrapani
class TrafficoVoipCTRL
set ip dscp af31
priority percent 20
or
policy-map QosIdcToTrapani
class TrafficoROUTING
set ip dscp cs6
bandwidth percent 3
random-detect
and
interface GigabitEthernet0/0
service-policy output QosIdcToTrapani
09-04-2014 09:32 AM
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You might misunderstand the purpose of the CBWFQ bandwidth statement. It guarantees a minimum, it doesn't limit the class from using all the link bandwidth.
The latter, though, isn't necessarily bad. Other classes should be able to obtain their bandwidth guarantees, and as you've defined FQ in the class, a high rate flow shouldn't monopolize the bandwidth (i.e. other flows will get their share to).
With QoS, the question shouldn't be whether your UDP traffic can acquire 80% of the link, but rather it is adverse to other applications when it does acquire 80%. If it is adverse, you can often just lower its bandwidth guarantee.
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