Question on prioritization of queues on Cisco ISR (QoS) - is it possible?

Question

Cisco

The situation is as follows - it is necessary to do, in fact, a banal prioritization of queues on several Cisco ISRs (3800 and 3900 series, IOS 15.1(1)T) in our mpls backbone.
It is necessary that the channel bandwidth be allocated stupidly according to the queue priorities - higher priority traffic should always take the bandwidth as much as it needs and crowd out the lower levels. And so on for each level of the hierarchy.
The LLQ mechanism is not suitable in this case, because it limits the upper threshold for traffic, and the LLQ queue itself is only one per interface. We also failed to implement this task with the classic CBWFQ - there is no task to give the service an SLA using bandwith, and traffic from different queues divides the bandwidth in excess of the specified bandwith equally. Tried experimenting with WRED parameters and queue sizes - no effect.
There is an idea to try the Priority Queueing mechanism, but there are big doubts about its relevance in mpls. Yes, and it is not flexible at all.
Maybe someone can suggest a nice solution or idea?)

Answer 1

Issue resolved. On Cisco hardware, this is not feasible, but since the task is not entirely correct, it’s not scary) We changed the formulation of the problem and solved everything through the classic CBWFQ queues.
By the way, on hardware from Juniper, what we wanted is quite possible to implement - QoS is much more flexible there