The value of vRtrLdpGenDistMethod specifies the label
distribution method used.
When vRtrLdpGenDistMethod has a value of 'downstreamOnDemand',
label bindings are distributed to the upstream LSR, for each FEC,
without requiring a request message for the FEC from the upstream
LSR.
When vRtrLdpGenDistMethod has a value of 'downstreamUnsolicited',
label bindings are distributed to the upstream LSR only when a
label request message is received.