I decided I will come out of "lurk mode" and try to express my thoughts about local-use addresses. I have been following the thread on the IETF general mailing list regarding site-local addresses. The following things may have already been discussed, as I only just recently subscribed to the IPNG mailing list. I think all unicast addresses should be "global", instead of having any scopes at all. I believe this would promote the whole E2E concept. Local-use addresses seem to be redundant. Why would one need to address a host on the same site or same link using an address other than its' global address? (Sorry if that is confusing) One scenario I thought of is back-end servers (ie: database servers) that do not need to be globally accessible, but other front-end servers (ie: web servers) need to communicate with these back-end servers. This is what a private address space would be for, and you would likely have multiple interfaces on seperate networks (one public, one private) to segregate the traffic. I suggest that: a) The site-local and link-local address scopes be abandoned. As I stated above, I believe they are redundant and therefore not needed. If you want to address all of the hosts at your site or on your link, why not use multicast? Are there any practical cases where one would use these scopes instead of global addresses that a private space or multi-cast would not solve? b) I believe that RFC 2462 (IPv6 Stateless Address Autoconfiguration) already deals with this, but I will mention it anyways; the link-local address space (or possibly some other space) be used as a fall-back for auto-configuration purposes. If a host is not configured with a static address, and does not have DHCP client capabilities or the host does not receive a response from a DHCP server, then an auto-configured address could be assigned to the interface. I think this would make it so that "it just works" if someone wants to plug a bunch of IPv6 hosts on to a LAN and use some type of neighbor disocvery mechanism to let the hosts find each other and start communicating. c) The link-local address space (or, again, some other space) be made available as private address space. It would for use by administrators of networks that are not planning to be connected to the Internet but still need an address space to use. Is this not the intention of RFC 1918 addresses as well? Is there any reason to not provide a private addres space? I don't want to start discussions about NAT because that's not what it the private address space will always be used for. Comments and constructive critisism are appreciated.