This is an issue that Meem noticed with the IPMP bits: http://zhadum.east/ws/seb/seb-ipobs/webrev.purge/
It's not a problem with the ipobs bits by themselves because ip_purge_allmulti() is always being called when the ill is being unplumbed, so ill_ipallmulti_cnt wrapping will never get noticed. With the Clearview IPMP bits, ip_purge_allmulti() also gets called when an interface joins an IPMP group. -Seb
