Cisco 9300 QoS Question

[mumbles202]

If migrating from a 3750 to 9300 configuring where the 3750 had "mls qos trust cos" under the interface configuration does anything need to be done for a similar setup for a 9300?  It's my understanding that the 9300 has QoS enabled by default w/ all ports trusting at L2 and L3 by default so that accomplishes what is configured on the 3750 other than if there is a non-default setting in the mls qos configuration.

[Reza Sharifi · Accepted solution]

That is correct.

• Catalyst 9000, Catalyst 3650/3850, and Catalyst 4500E use IOS Modular QoS Command Line
Interface (MQC)
• QoS is enabled by default
• All ports trust at layer 2 and layer 3 by default

for more info see page 19 in this link:

https://www.ciscolive.com/c/dam/r/ciscolive/emea/docs/2019/pdf/BRKCRS-2501.pdf

HTH

[mumbles202]

Thanks for the assistance and confirming.  Is there any equivalent for 

srr-queue bandwidth share 1 30 35 5
priority-queue out

or is the AutoQos that is enabled on the interfaces comparable?

[Joseph W. Doherty]

Yes, although unsure what the AutoQoS uses for its defaults, or what the switch uses for its QoS defaults if AutoQoS not used.  In other words, you likely need to configure QoS statements to match your PQ and 30:35:5, just as the latter had to be configured too.

One big difference, the 3750 series has defaults for how it maps DSCP (or CoS) values into its four egress queues.  I suspect, w/o AutoQoS all traffic will default into the BE queue.

The newer switches' QoS is much like ISR QoS.  Their QoS still isn't a full featured as an ISRs, but it does offer much more than a 3750's QoS.

[mumbles202]

Ok thanks.  So I can basically setup class-maps that mimic the 3750 dscp maps, then create a policy-map calling these 4 maps and set the bandwidth there and then on the interface call it as a service-policy.    The AutoQos input service-policy looks to trust COS so that should be ok as that is what the old configuration was doing.

[Joseph W. Doherty]

Correct.

[engineer467]

Hi,

Can you please share the config if it worked.

Thanks.