Applying MPLS EXP Classifiers for Explicit-Null Labels
When you configure MPLS explicit-null labels, label 0 is advertised to the egress router of an LSP. When label 0 is advertised, the egress router (instead of the penultimate router) removes the label. Ultimate-hop popping ensures that any packets traversing an MPLS network include a label. For more information about explicit-null labels and ultimate-hop popping, see the MPLS Applications User Guide.
On M320 and T Series routers, when you configure MPLS explicit-null labels with an MPLS EXP classifier, the MPLS EXP classifier can be different from an IPv4 or IPv6 classifier configured on the same logical interface. In other words, you can apply separate classifiers for MPLS EXP, IPv4, and IPv6 packets per logical interface. To combine an EXP classifier with a distinct IPv6 classifier, the PIC must be mounted on an Enhanced FPC.
For M Series routers, MPLS explicit-null labels with MPLS EXP classification are supported if you set the same classifier for EXP and IPv4 traffic, or EXP and IPv6 traffic.
For more information about how IPv4 and IPv6 packet classification is handled, see Applying Behavior Aggregate Classifiers to Logical Interfaces.
To configure an MPLS EXP classifier for explicit-null labels:
To apply the MPLS EXP classifier to the logical interface:
Specify the physical and logical interface names on which you want to apply the classifier.
[edit] user@host# edit class-of-service interfaces interface-name unit logical-unit-number
Specify the classifier type and name you want to apply to the interface.
[edit class-of-service classifiers interfaces interface-name ] user@host# set classifiers exp classifier-name
When a packet with a single label is received, if the
label is an explicit-null label (0 or 2), the label is popped first,
making the EXP information no longer available. The subsequent packet
classification is based on the IPv4/IPv6 payload. Starting with Junos OS 18.1R1, PTX Series routers with
third-generation FPCs (FPC3) support a new CLI option, [explicit-null-cos inet|inet6] at the [edit forwarding-options] hierarchy level, that makes the packet classification based on the
MPLS EXP value rather than on the payload, thus preserving the MPLS
classification of the packet.
[explicit-null-cos inet|inet6] at the [edit forwarding-options] hierarchy level, that makes the packet classification based on the
MPLS EXP value rather than on the payload, thus preserving the MPLS
classification of the packet.