The FR PIPQ feature provides an interface-level priority queueing scheme in which prioritization is based on destination permanent virtual circuit (PVC) rather than packet contents. For example, FR PIPQ allows you to configure a PVC transporting voice traffic to have absolute priority over a PVC transporting signalling traffic, and a PVC transporting signalling traffic to have absolute priority over a PVC transporting data.

FR PIPQ provides four levels of priority: high, medium, normal, and low. The Frame Relay packet is examined at the interface for the data-link connection identifier (DLCI) value. The packet is then sent to the correct priority queue based on the priority level configured for that DLCI.

Note	When using FR PIPQ, configure the network so that different types of traffic are transported on separate PVCs. FR PIPQ is not meant to be used when an individual PVC carries different traffic types that have different quality of service (QoS) requirements.

You assign priority to a PVC within a Frame Relay map class. All PVCs using or inheriting that map class will be classed according to the configured priority. If a PVC does not have a map class associated with it, or if the map class associated with it does not have priority explicitly configured, then the packets on that PVC will be queued on the default "normal" priority queue.

If you do not enable FR PIPQ on the interface using the frame-relay interface-queue prioritycommand in interface configuration mode, configuring PVC priority within a map class will not be effective. At this time you have the option to also set the size (in maximum number of packets) of the four priority queues.

FR PIPQ works with or without Frame Relay traffic shaping (FRTS) and FRF.12. The interface-level priority queueing takes the place of the FIFO queueing or dual FIFO queueing normally used by FRTS and FRF.12. PVC priority assigned within FR PIPQ takes precedence over FRF.12 priority, which means that all packets destined for the same PVC will be queued on the same interface queue whether they were fragmented or not.

Note	Although high priority PVCs most likely will transport only small packets of voice traffic, you may want to configure FRF.12 on these PVCs anyway to guard against any unexpectedly large packets.

FR PIPQ provides four levels of PVC priority: high, medium, normal, and low. This method of queueing ensures that time/delay-sensitive traffic such as voice has absolute priority over signalling traffic, and that signalling traffic has absolute priority over data traffic, providing different PVCs are used for the different types of traffic.

1.    Router(config)# map-class frame-relay map-class-name

2.    Router(config-map-class)# frame-relay interface-queue priority {high | medium| normal | low}

1.    Router(config)# interface type number [name-tag]

2.    Router(config-if)# encapsulation frame-relay[cisco | ietf]

3.    Router(config-if)# frame-relay interface-queue priority [high-limit medium-limit normal-limit low-limit]

1.    Router(config-if)# frame-relay interface-dlci dlci

2.    Router(config-fr-dlci)# class map-class-name

To verify the configuration of FR PIPQ, use one or more of the following commands in privileged EXEC mode:

Router# show frame-relay pvc [interface  interface][dlci]

Router# show interfaces [type number][first][last]

Router# show queueing [custom | fair | priority | random-detect [interface atm_subinterface [vc [[vpi/] vci]]]]

To monitor and maintain FR PIPQ, use one or more of the following commands in privileged EXEC mode:

Router# debug priority

Router# show frame-relay pvc [interface  interface][dlci]

Router# show interfaces [type number][first][last]

Router# show queue  interface-name interface-number [vc [vpi/] vci][queue-number]

Router# show queueing [custom | fair | priority | random-detect [interface atm_subinterface [vc [[vpi/] vci]]]]

This example shows the configuration of four PVCs on serial interface 0. DLCI 100 is assigned high priority, DLCI 200 is assigned medium priority, DLCI 300 is assigned normal priority, and DLCI 400 is assigned low priority.

The following commands configure Frame Relay map classes with PVC priority levels:

Router(config)# map-class frame-relay HI
Router(config-map-class)# frame-relay interface-queue priority high
Router(config-map-class)# exit
Router(config)# map-class frame-relay MED
Router(config-map-class)# frame-relay interface-queue priority medium
Router(config-map-class)# exit
Router(config)# map-class frame-relay NORM
Router(config-map-class)# frame-relay interface-queue priority normal
Router(config-map-class)# exit
Router(config)# map-class frame-relay LOW
Router(config-map-class)# frame-relay interface-queue priority low
Router(config-map-class)# exit

The following commands enable Frame Relay encapsulation and FR PIPQ on serial interface 0. The sizes of the priority queues are set at a maximum of 20 packets for the high priority queue, 40 for the medium priority queue, 60 for the normal priority queue, and 80 for the low priority queue.

Router(config)# interface Serial0
Router(config-if)# encapsulation frame-relay
Router(config-if)# frame-relay interface-queue priority 20 40 60 80

The following commands assign priority to four PVCs by associating the DLCIs with the configured map classes:

Router(config-if)# frame-relay interface-dlci 100
Router(config-fr-dlci)# class HI
Router(config-fr-dlci)# exit
Router(config-if)# frame-relay interface-dlci 200
Router(config-fr-dlci)# class MED
Router(config-fr-dlci)# exit
Router(config-if)# frame-relay interface-dlci 300
Router(config-fr-dlci)# class NORM
Router(config-fr-dlci)# exit
Router(config-if)# frame-relay interface-dlci 400
Router(config-fr-dlci)# class LOW
Router(config-fr-dlci)# exit