Classifying Packets by Egress Interface
For Juniper Networks M320 Multiservice Edge Routers and T Series Core Routers with the Intelligent Queuing (IQ), IQ2, Enhanced IQ (IQE), Multiservices link services intelligent queuing (LSQ) interfaces, or ATM2 PICs, you can classify unicast and multicast packets based on the egress interface. For unicast traffic, you can also use a multifield filter, but only egress interface classification applies to multicast traffic as well as unicast traffic. If you configure egress classification of an interface, you cannot perform Differentiated Services code point (DSCP) rewrites on the interface. By default, the system will not perform any classification based on the egress interface.
To enable packet classification by the egress interface, you first configure a forwarding class map and one or more queue numbers for the egress interface at the [edit class-of-service forwarding-classes-interface-specific forwarding-class-map-name] hierarchy level:
For T Series routers that are restricted to only four queues, you can control the queue assignment with the restricted-queue option, or you can allow the system to automatically determine the queue in a modular fashion. For example, a map assigning packets to queue 6 would map to queue 2 on a four-queue system.
 | Note: If you configure an output forwarding class map associating a forwarding class with a queue number, this map is not supported on multiservices link services intelligent queuing (lsq-) interfaces. |
Once the forwarding class map has been configured, you apply the map to the logical interface by using the output-forwarding-class-map statement at the [edit class-of-service interfaces interface-name unit logical-unit-number ] hierarchy level:
All parameters relating to the queues and forwarding class must be configured as well. For more information about configuring forwarding classes and queues, see Configuring Forwarding Classes.
This example shows how to configure an interface-specific forwarding-class map named FCMAP1 that restricts queues 5 and 6 to different queues on four-queue systems and then applies FCMAP1 to unit 0 of interface ge-6/0/0:
Note that without the restricted-queue option in FCMAP1, the example would assign FC1 and FC2 to queues 2 and 1, respectively, on a system restricted to four queues.
Use the show class-of-service forwarding-class forwarding-class-map-name command to display the forwarding-class map queue configuration:
user@host> show class-of-service forwarding-class
FCMAP2Forwarding class ID Queue Restricted queue FC1 0 6 3 FC2 1 5 2 FC3 2 3 3 FC4 3 0 0 FC5 4 0 0 FC6 5 1 1 FC7 6 6 2 FC8 7 7 3
Use the show class-of-service interface interface-name command to display the forwarding-class maps (and other information) assigned to a logical interface:
user@host> show class-of-service interface ge-6/0/0 Physical interface: ge-6/0/0, Index: 128 Queues supported: 8, Queues in use: 8 Scheduler map: <default>, Index: 2 Input scheduler map: <default>, Index: 3 Chassis scheduler map: <default-chassis>, Index: 4 Logical interface: ge-6/0/0.0, Index: 67 Object Name Type Index Scheduler-map sch-map1 Output 6998 Scheduler-map sch-map1 Input 6998 Classifier dot1p ieee8021p 4906 forwarding-class-map FCMAP1 Output 1221 Logical interface: ge-6/0/0.1, Index 68 Object Name Type Index Scheduler-map <default> Output 2 Scheduler-map <default> Input 3 Logical interface: ge-6/0/0.32767, Index 69 Object Name Type Index Scheduler-map <default> Output 2 Scheduler-map <default> Input 3
