[c-nsp] IPv6 Stateful DHCP on ISR 880

[Nick Hilliard]

On 02/07/2012 18:54, Gert Doering wrote:
> Not using a /64 for the LAN.

To flesh this out, there is no subnet mask option in dhcpv6: it's
hard-coded to /64 because the default lan subnet is /64.

I.e. even though the "address prefix" command gives you the impression that
it will accept /96, this mask is not transmitted to the dhcpv6 client.
It's the client which applies the /64 mask.

If you're doing subnetting for a big number of sites, you should ask for
enough address space for them all.  There's plenty of IPv6 address space
around - no need to conserve it.  In fact, your provider should be able to
give you a /48 without any justification at all:  that's 2^16 subnets.  Are
you really operating more than 65k v6 subnets?

Nick