Currently, ether1 and ether3 (which do not share a bridge) are connected directly to the AT&T Gateway. Each interface has a DHCPv6 client, and the gateway gave each a different /64 prefix.
- The prefix ether1 pulled is being advertised on COMMON_VLAN, and all devices on that VLAN are getting the prefix as expected.
- The prefix ether3 pulled is being advertised on BASE_VLAN, which is only occupied by MikroTik devices (a hAP ac³, a CRS112-8P-4S-IN, and a hEX). The hEX and the hAP ac³ are connected to the CRS112 on trunk ports, and ultimately everything has to go through the CRS112 to get to the hEX S.
The way I’ve set this up, I can get one /64 prefix per available interface on the AT&T gateway for a maximum of 4. I could probably get around this by bypassing the gateway altogether (per http://forum.mikrotik.com/t/bypassing-at-t-residential-gateways-with-mikrotik/135563/1), but I don’t have enough VLANs to make the full /60 necessary.
I’ll look around the forum some more, but the RAs not being taken up on the downstream devices is likely something silly I’ve done with VLAN routing. I was more interested in why I had routes with no gateway, and I think the answer is this implementation is a bit kludgey.