QOS On Core 9500 And Classification

[CANMORMON]

I am looking at configuring QOS on a Catalyst 9500 which will be our core switch. I am following the Cisco Catalst 9000 Series QoS Design which I have also attached.

In the document it seems to say that if you are trusting the DSCP markings you need to just employ Queuing.

In the design guide they have a policy-map NBAR-MARKING that classifies the traffic coming into the switch

int gig 0/0

service-policy input NBAR-MARKING

They then have another policy-map 2P6Q3T-WRED that does the queuing.

int gig 0/0

service-policy output 2P6Q3T-WRED

My question is if I am trusting all DSCP Markings coming into the switch do I still need to have a service-policy input NBAR-MARKING on my interfaces which classifies the incoming traffic?

int ten 0/1

service-policy input NBAR-MARKING

service-policy output 2P6Q3T-WRED

or just configure queueing only

int ten0/1

service-policy output 2P6Q3T-WRED

[brselzer · Accepted solution]

Hello,

If your traffic is something like VOIP where the phone marks the traffic, then you can just trust it and you do not need a marking policy. However, if your traffic is not marked at the source, you will still need to have your own marking policy that puts the correct DSCP marking on it. 

Hope that helps!

[CANMORMON]

Thanks