what is the use of auto Qos Trust command ?

[aci_network_test]

Hi Team , 

We have below QOS configuration on one of the interface , Can someone explain me how this works ? With and without this configuration on the interface connecting to end device like CAMERA or PRINTER ? 

auto qos trust
service-policy input AutoQos-4.0-Trust-Cos-Input-Policy
service-policy output AutoQos-4.0-Output-Policy

[balaji.bandi]

Auto QOS make life simpler again depending on use cases, below are some good explanation from cisco :

https://www.cisco.com/en/US/technologies/tk543/tk879/technologies_qas0900aecd8020a589.html

see the Camera and another device example:

https://www.cisco.com/en/US/docs/switches/lan/catalyst3850/software/release/3.2_0_se/multibook/configuration_guide/b_consolidated_config_guide_3850_chapter_010001.html

[aci_network_test]

Can you confirm if qos is not configured on one of the interface where the printer is connected will it have any impact ? Or will it not allow the printer to get the ip assigned from the dhcp ? 
we learn mac on the interface but I don’t see ip arp on the l3 switch ..

Will this issue be due to auto qos not being configured on the interface ???

[balaji.bandi]

yes, you can do if the device does not require QoS like a printer makes it a simple config on the port. and yes device gets an IP address from DHCP.

[aci_network_test]

Apr 13 08:34:28.114: %DHCP_SNOOPING-5-DHCP_SNOOPING_UNTRUSTED_PORT: DHCP_SNOOPING drop message on untrusted port, message type: DHCPACK, MAC sa: 0023.047f.4c3c

On the L2 (9200 IOS-XE) switch I see this message . This 0023.047f.4c3c is learned from uplink interface Gi1/0/1 of L2 switch and belongs to svi vlan10 MAC.

And on vlan10 we have Ip helper configured , so our dhcp is on windows server . 

Can you please suggest what can be checked further or any configuration change has to be done. .

[Georg Pauwen]

Hello,

what exactly is the issue ? Is the printer not getting an IP address ? Post the full running configurations (sh run) of the 9200 switch and the gateway...

[aci_network_test]

Yes printer is not getting the IP address ...