On systems with many interfaces smcrouted will fail due to exhaustion of the VIF/MIF space. There is,
per routing table, usually only 32 VIFs (IPv4) and 32 MIFs (IPv6) available in total.

smcrouted should allocate a VIF/MIF per interface on demand instead, and also free unused VIF/MIF on removal of routes. A simple reference count per interface should be sufficient.