BSR role in fault recovery

If the hold-time maintained in the BSR for a given C-RP's latest advertisement expires before being refreshed by a new advertisement from the C-RP, the non-reporting C-RP is removed from the domain. In this case, the removed C-RP's multicast groups are re-assigned to other C-RPs. (If no other C-RPs or static RPs in the domain are configured to support a multicast group from the non-reporting C-RP, that group becomes unavailable in the domain.)