QoS cisco 9300 with Auto QoS

Routing & Switching Quality of Service
1

I would like to know how QoS is honored in cisco 9300 Cat switches, suppose you have a windows machine running Teams and DSCP value is set in that, this machine is connected to a cisco phone which in turn is connected to a 9300 Switch which is enabled with Auto QoS (with Layer 2 CoS value) ,eg: LAPTOP(Teams-DSCP enabled via GRPPOLICY) —CISCO PHONE -----PORT 1/0/20(Cisco 9300 switch) (switch access vlan 10, sw voice vlan 20-Auto QoS enabled for CoS- Qos trust cos) will cisco 9300 honor the DSCP value of Team , or do the port need to be changed from QoS trust dscp ? …there is no MLS command in 9300 # Only want to know if DSCP will be honored or not , reason is it does not show any output

show policy-map interface GigabitEthernet1/0/20

GigabitEthernet1/0/20

  Service-policy input: AutoQos-4.0-Trust-Cos-Input-Policy

  Class-map: AutoQos-4.0-Output-Priority-Queue (match-any)
      0 packets
      Match:  dscp cs4 (32) cs5 (40) ef (46)
        0 packets, 0 bytes
        5 minute rate 0 bps
      Match: cos  5
        0 packets, 0 bytes
        5 minute rate 0 bps
      Priority: 30% (300000 kbps), burst bytes 7500000,
2

Hello Binoy

When you configure auto QoS on a 9300 there are a few restrictions involved. According to this Cisco Documentation:

The trust device device_type command available in interface configuration mode is a stand-alone command on the switch. When using this command, if the connected peer device is not a corresponding device (defined as a device matching your trust policy), both CoS and DSCP values are set to “0” and any input policy will not take effect. If the connected peer device is a corresponding device, input policy will take effect.

If you have trust device cisco-phone, on the interface, then only the packets from the phone will maintain their DSCP/CoS values. Any traffic from the connected PC will have its CoS and DSCP values set to 0.

In order to have the device honour the DSCP/CoS values, you can use the auto qos trust command on the interface. More about this command can be found here:

I hope this has been helpful!

Laz