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Bronze

Nest QoS with shaping - getting drops

    HI - I have a 3800 running 12.4 with a outbound shaped nest Qos tied to a subinterface G0/0.12 which is trunk downstream to a 3500. I am getting drops on the "sh policy-manager inter g0/0.12 so know that shaping which is 1.5mbps is dropping my packets. The 3500 looks clean

3800:

policy-map A

class-map A

bandwidth 30% etc..

policy-map B

class class-default

shape 15000000 150000

service-policy A

inter gig 0/0

duplex fd

speed 100

inter gig 0/0.12

service-policy output policy-mapB

3500:

int fa0/1

switchport trunk...

duplex fd

speed 100

the routing is that host goes up to the 3800 and out a wan link but if wan is down, it hairpins back down from 3800 to 3500 which has a backup link on one of the ports. when we test wan down, or even when it is up, I see shape dropping packets

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4 REPLIES
Bronze

Nest QoS with shaping - getting drops

So what seems wrong? Shaping is not magic - it may drop packets when shaping queue fills up. How much bandwidth does your traffic consumes when wan is up?

Bronze

Nest QoS with shaping - getting drops

arghh...even though the QoS is explictly applied to the subinterface  gig 0/0.12, it is implicitly applied to the main

gig 0/0 so instead of G0/0 having 1000mbps, the traffic is shaped down to 1.5Mbps - There is no QoS applied to the main interface

Since the G0/0 has other subint, it is dropping traffic as a bottleneck due to this QoS.

Super Bronze

Nest QoS with shaping - getting drops

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aamercado wrote:

arghh...even though the QoS is explictly applied to the subinterface  gig 0/0.12, it is implicitly applied to the main

gig 0/0 so instead of G0/0 having 1000mbps, the traffic is shaped down to 1.5Mbps - There is no QoS applied to the main interface

Since the G0/0 has other subint, it is dropping traffic as a bottleneck due to this QoS.

Hmm, wouldn't expect it to do that. What version of 12.4 are you running?

Bronze

Nest QoS with shaping - getting drops

Yes, I agree with Joseph - it is really unexpected. May be IOS update will help?..

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