The value of vRtrPimNgIfMcacPreRsvdMandBW specifies the bandwidth
pre-reserved for all the mandatory channels on a given interface
in kilo-bits per second(kbps).
If the value of vRtrPimNgIfMcacUnconstrainedBW is '0', no mandatory
channels are allowed. If the value of vRtrPimNgIfMcacUnconstrainedBW
is '-1', then all mandatory and optional channels are allowed.
If the value of vRtrPimNgIfMcacPreRsvdMandBW is equal to the value of
vRtrPimNgIfMcacUnconstrainedBW, then all the unconstrained bandwidth
on a given interface is allocated to mandatory channels configured
through multicast cac policy on that interface and no optional
groups (channels) are allowed.
The value of vRtrPimNgIfMcacPreRsvdMandBW should always be less than
or equal to that of vRtrPimNgIfMcacUnconstrainedBW. An attempt to set
the value of vRtrPimNgIfMcacPreRsvdMandBW greater than that of
vRtrPimNgIfMcacUnconstrainedBW will result in inconsistent value
error.