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Configuring Catalyst 3850 for QoS/Shaping on 802.1Q VLANs


Hi Community,

I am in desperate need of direction/assistance. In trying to achieve my aim, I keep going around in circles, not getting any closer.

I have a Catalyst 3850 with several VLAN Trunk Ports with multiple VLANs on each.

I need to apply shaping to the egress of each VLAN for two traffic classes: Voice and a single Data class

I wish to apply a guaranteed non buffered queue for the Voice and

A Shape Average queue for the data class

Each time I try a config I get the following error notification:

% Queuing actions supported only with dscp/cos/qos-group/precedence based classification!!!

I assume I am omitting a step but am lost.

Are there any step by step tutorials available that would cover setting up such a Config?

I am desperate for assistance.




Joseph W. Doherty
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Hall of Fame Master

I don't really "know" a 3850's QoS features, especially regarding shaping.  I "know" the earlier 3750 had both an inexact port "shaping" feature, and supported egress queue "shaping", but it also supported only 4 egress queues, one of which could be configured PQ.

I believe [?] the 3850 supports 8 egress queues, of which 1 (maybe 2?) can be PQ.  Don't know what, "shaping" it supports.  (Its QoS features should be documented in the configuration manual and guide for your IOS version.)

What you might be able to do, is direct all your VLAN VoIP traffic to a single egress PQ and direct VLAN data traffic to up to 7 other queues, which support "shaping" per queue.  (They should support relative dequeuing priorities.)

If you identify the IOS being used, version and feature set, I could look over the documentation and, possibly, assist you further.

Hi Joseph,

Thanks for the response! My 3850 is running IOS Version 16.3.


From a quick read of the user guide, the 3850 supports 8 egress queues, two of which can be configured as PQs, shaping on egress queues (but on physical ports).

What might work, assuming you don't need more than 8 classes, is to logically (using QoS groups) classify all traffic, VoIP to be directed to your physical (trunk) port's PQ, and up to 7 VLANs into physical (trunk) port queues, each shaped as desired.

Hi Joseph,
Thanks for taking the time to look into this and your feedback. From your comments, it is clear where I was always going wrong - I have been trying to effectively create 2 QoS queues within each VLAN Class-Map.
One further question - Does the 8 Queue limit apply to the switch across all physical ports, or is it 8 per Physical Port?
Thanks for your help - I appreciate you giving your time!

8 per physical port.