Dave Taht wrote:
The proper solution is to have end to end multihoming:
I'd never read that. We'd made openwrt in particular use "source specific routing" for ipv6 by default, many years ago, but I don't know to what extent that facility is used.
Considering that most, if not all, multihomed sites should have rich (maybe full) routing table in some part (at least) of the sites between exit routers to balance load between the routers, I can't see why source specific routing was considered necessary only to cause routing loops. For multihoming with PA address ranges with plain TCP/UDP, what is necessary for ISP failure is to have routing protocols to carry proper source address ranges for each routing table entry and to modify end systems to listen to routing protocol and choose proper source address, which is against the poor architecture of IPv6/ND to assume intelligent routers and dumb hosts. But, even with that, if some ISP fails, TCP/UDP through the ISP will fail and must be restarted with new source address, which is not very useful. Moreover, if destination is also inside another multihomed site with PA address ranges, all the destination addresses must be tried. So, as modifying end systems is inevitable, there is no reason not to support full end to end multihoming including modifications to support multiple addresses by TCP and some applications. Masataka Ohta