Auto Qos Trust DSCP vs. Trust DSCP

[ghostpepper]

Does anyone know what the difference is between Auto Qos Trust DSCP vs. Trust DSCP on a 9200L switch port?  Something is telling me that the latter will just pass on the DSCP value where the first will actually apply QoS to the port with what was learned with AutoQOS.  I read somewhere there is a 72-hour learning period but I don't know how true that is as I can't find documentation to back that up.  So with QoS... I just need to send any existing DSCP value I get from the PC or Phone to my upstream router.  I don't necessarily need QoS on the switch as I am barely scratching the surface of this thing.

[chrihussey · Accepted solution]

Hello

Trust dscp is the default configuration for the port and it will simply pass the dscp markings and no inbound or outbound policy maps are applied. With the auto-qos trust dscp inbound and outbound auto generated policies are applied. However the inbound policy map "AutoQos-4.0-Trust-Dscp-Input-Policy" really doesn't do anything and is just like trust dscp, and the outbound policy map "AutoQos-4.0-Output-Policy" does do QoS based on various types of traffic. 

However, if your not scratching the surface and are just using the port for general use the default will be fine. QoS can be challenging to implement if you really need it and the auto qos feature is a great help.

Hope this helps

[ghostpepper]

Ya that is about what I was thinking but thanks for confirming so I know I'm not losing my mind here   trust dscp is fine in my case is this is a small branch office where we'd never overwhelm the switch per se but could overwhelm the circuit.  I wanted to make sure that my dscp values just get passed upstream so the router can take action.