This object specifies whether multicast forwarding
is supported on this interface for a particular
internet address type.
'notCapable' - A read-only value which indicates that
this interface is not capable of multicast
forwarding for this internet address
type.
This value cannot be used in SET operation.
'enable' - multicast forwarding is enabled.
'disable' - multicast forwarding is disabled.
This object is not writable if the value of this object
is 'notCapable'.