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COS Downmarking on ASR903

j.hoffmann
Level 1
Level 1

Hi,

it is my intention to trust incoming COS values on the UNI Ingress of an ASR903 (RSP3, IOS 3.18.05.SP.156-2.SP5 ). On the UNI port, a service instance ethernet with an associated bridge domain is configured. DSCP is not analyzable in this setup.

In the first approach, I've configured a mapping of the incoming COS values with conditionally set QoS groups using a CIR threshold. Conform action should use the set-qos-transmit command to set a QoS group corresponding to the original COS value. Exceeding action, also with set-qos-transmit should perform an implicit COS downmarking to a lower COS using a "lower" QoS group.

BUT, using this policy in an input service-policy on the UNI leads to this failure message:

ASR903(config-if-srv)#service-policy input UNI_INGRESS
exceed action: set-qos-transmit cannot be configured for this interface
Configuration failed on GigabitEthernet0/1/2: EFP 21

 

I've discovered that the set-qos-transmit command is usable only with RSP1 and RSP2, but not with RSP3.

But, I don't see any other possibilities to downmark incoming traffic if this traffic exceeds a configured CIR:

ASR903(config-pmap-c-police)#exceed-action ?
drop drop packet
set-dscp-transmit set dscp and send it
set-prec-transmit rewrite packet precedence and send it
set-qos-transmit set qos-group and send it
transmit transmit packet

 

How should I downmark exceeding traffic if L3 QoS parameters are not usable and set-qos-transmit is not allowed?

I would be deeply grateful for any helpful advice!

Regards,

Jens

 

 

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