I need to prepare a QoS configuration on a 7504R with 7500R and 7500R2 linecards (Jericho and Jericho+) and I don’t have access to the switches, so I would like to clarify a couple of points.
First of all, most of the time, classification will be done by an ACL. Do you know if the following limitations still apply to 7500R ? :
Layer 4 port ranges are not supported for ACL based QoS. The ranges will be expanded into multiple TCAM rules and programmed in the hardware
User cannot apply more than 31 QoS service policies per chip on L3 interfaces
Then, the documentation states that, for Jericho platforms : “The port-trust default for switched ports is CoS. The port-trust default for routed ports is DSCP.”
Let say I have a policy map which call classes which use ACL and then set a DSCP (pretty basic).
What will happen if I receive a traffic without any QoS tag on a L2 802.1Q interface where this policy-map is applied ? The switch will use the Cos to traffic class map or the DSCP to traffic class map (I guess the first one) ? Should I apply the policy map on the physical L2 interface or the SVI interface ?
Globally, the policy-map will be used to set the values and the trust mode will determine which one I use to derive the traffic-class if I’m not mistaken.
Finally, when leaving the egress interface, the CoS will be rewritten according to the Traffic Class to CoS Rewrite map and the DSCP will not be rewritten, right ?
Thanks for your help.
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