Failover IPv6 with multiple PA prefixes (Was: IPv6 fc00::/7 -Unique local addresses)

Mon Nov 1 01:49:10 UTC 2010

> 
> why not just use link-local then? eventually you'll have to connect
> that network with another one, chances of overlap (if the systems
> support real revenue) are likely too high to want to pay the
> renumbering costs, so even link-local isn't a 100% win :(
> globally-unique is really the best option all around.
> 
> -chris

Routing mostly on the end host is why.  If I have 10 clustering vlans
(which will never get routed outside the cluster) and they all have the
same link local address (if the vlan interfaces are configured on the
same ethernet device, they will all have the same link local address),
how do they know which vlan interface to send the packet out?  All of
them will have exactly the same link local address.  And I have an
aversion to putting link local IPs in DNS as everyone thinks the
hostname is on the local link in case of some kind of dns screwup.