Dear WG, Apologies if this mail is off topic here. I have a question about BCOP-690 wrt SLAAC BCOP-690 says: Using a /64 prefix from a dedicated pool of IPv6 prefixes is the most common scenario and currently the best practice. A separate block of IPv6 space is allocated for the WAN links to the end customer CPEs, so that when CPE connects to the network and performs router discovery, a /64 prefix is used to number both ends of the connection. My understanding of this recommendation is that in an ISP scenario, each RG will be assigned a seperate /64 prefix for CPE WAN. The ISP BRAS or BNG is also expected to send periodic multicast RA. My question is how a multicast RA can be sent to a VLAN, in which each RG is expected to have a different /64 prefix? R-43 of TR-177 says: The BNG MUST be configurable to send multicast RA messages that do not contain a Prefix Information Option (PIO), in order to advertise the default router address. R-44 says: The BNG SHOULD support sending periodic and solicited multicast RA messages having the unicast MAC address of the RG or of the hosts behind a bridged RG (see RFC 6085 [26]). Reading these two together, is it correct to say that BNG should be sending out periodic multicast RA without PIO, but RA with PIO should be sent only as a reply to an RS message from RG, with multicast IPv6 destination address but with unicast link-layer address of RG. Thanks and Regards, X.