IPv6 alias masks/masks for routed aliases

[Charles Sprickman]

Hello,

I'm having trouble finding the canonical answer on two uses of 
interface aliases.

First, the easy one.  For IPv6 aliases, what is the proper subnet?  I've 
found some old info on the WIDE site stating that it should be the same as 
the main interface (ie: if I've got a /48, my alias should use /48 as 
well).  This runs contrary to what I know of IPv4 aliases - if you've 
already got another IP on the adapter, further aliases in the same subnet 
should be created with a /32 mask.

And the second one, which is also probably easy.  We're going to move at 
some point from a bunch of subnets on the same wire to having our own 
router that gets our blocks routed to it.  At that point I'd like to move 
to routing individual IPs (or small subnets) to each host behind the 
router.

For example, say we have the following routed to our router:

10.1.0.0/27
10.2.0.0/27
10.3.0.0/27

All the hosts behind our router are in 10.1.0.0/27.  I want to send some 
IPs from 10.2.0.0/27 and 10.3.0.0/27 to a host at 10.1.0.2, so I do the 
equivalent of "ip route 10.2.0.0 255.255.255.248 10.1.0.2" (cisco speak) 
on the router box.  How should the aliases on 10.1.0.2 be defined?  Should 
they all have /32 masks?  Should the first get a /29 and the rest a /32?

Is this even a valid config?  In reality, we have way more subnets, 
totally non-contiguous, varying masks.  With VRRP on the provider's side, 
we immediately lose 2 IPs from each subnet in our current setup, plus the 
network and broadcast IPs.  I'm hoping that in a routed setup I can regain 
not only the VRRP IPs but the top and bottom of each subnet... 
Considering the scarcity of IPs these days, that would be a big help.

Thanks,

Charles