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New Member

PQ/CBWFQ Algorithm

Given that I am configuring PQ/CBWFQ over MPLS and using rate limiting to mark the packet on input. On congestion does the packet go thru three different software modules ie the policy first, if policy is oversubscribed then second, the fair queueing module to ensure that higher precedence packets be de-queued before the lower precedence packets and thirdly the WRED module to ensure that flows within each queue are dropped.

How does the PQ/CBWFQ interact with the hardware/particle buffers (2600) on the serial interface- for exaple low queue has all the bandwidth of the serial but a high queued packet is input to the router- does the interupt clear the output harware/particle buffers to ensure the high queued packet is serialised before all the low queue data???

Any information regards to above gratefully accepted.

New Member

Re: PQ/CBWFQ Algorithm

The document 'Deploying Guaranteed-Bandwith Services with MPLS' will help. It is available at

Another great place to look at is 'MPLS Class of Service (CoS)' at the URL