This command enables or disables whether PHP is requested by the egress LER. If vlan all is selected, PHP is enabled on all VLANs on which MPLS has been configured. By default, PHP is disabled.
When PHP is enabled, PHP is requested on all LSPs for which the switch is the egress LER.
PHP is requested by assigning the Implicit Null Label in an advertised mapping. PHP is always performed when requested by a peer (for example, when acting as an intermediate LSR).