(Optional) Configuring the PHP Feature
Context
No label needs to be swapped on the egress node of an LSP. PHP can be configured on the egress node to allow the LSR at the penultimate hop to pop out the label from an MPLS packet and send the packet to the egress node. After receiving the packet, the egress node directly forwards the packet through an IP link or according to the next layer label. PHP helps reduce the burden on the egress node.
Procedure
- Run system-view
The system view is displayed.
- Run mpls
The MPLS view is displayed.
- Run label advertise { explicit-null | implicit-null | non-null }
The label allocated to the LSR at the penultimate hop is configured.
The egress node can allocate different labels to the PHP based on the parameter setting.
implicit-null: default value, which indicates that PHP is supported. If this parameter is configured, the egress node allocates an implicit null label with the value of 3 to the LSR at the penultimate hop.
explicit-null: PHP is not supported. If this parameter is configured, the egress node allocates an explicit null label with the value of 0 to the LSR at the penultimate hop. The explicit-null parameter can be configured when MPLS QoS attributes are used.
non-null: PHP is not supported. If this parameter is configured, the egress allocates a common label with a value greater than or equal to 16 to the LSR at the penultimate hop.
After the label advertise command is run to change the label distribution mode on the egress node, the modification takes effect on new LSPs but not on existing LSPs. To enable the modification to take effect on the existing LSPs, run the reset mpls ldp or lsp-trigger command.