shim6 (was Re: IPv6 news)

Fri Oct 14 20:11:18 UTC 2005

Daniel Roesen wrote:
> On Fri, Oct 14, 2005 at 07:27:37PM +0000, bmanning at vacation.karoshi.com wrote:
> 
>>	the kicker here is that the applications then need some
>>	serious smarts to do proper source address selection.
> 
> 
> Nope. The ULID is supposed to be static, globally unique. Just not
> globally routed. Seperating topology from identification.
> 
> Something I didn't see discussed yet is that shim6 sites would need to
> get a globally unique, provider independent /48 or larger... which folks
> could start to announce. But I guess that address space would come from
> blocks earmarked as "non-routable, it's a bogon, bad IP space, filter in
> BGP at first sight!". :-)

Actually, doing multihoming and getting PI space are orthogonal in
shim6 last I knew. That is, you could get address space from your N
providers and have one of the providers, say Provider X, to be the
ULID for the end points. Should Provider X's link(s) go down, shim6
will ensure it all still works (which is, after all, the whole point).

Getting PI space is really an administrative and economic issue. It is
not a technical requirement of shim6. From draft-ietf-shim6-arch-00.txt,

3.  Endpoint Identity

    There are a number of options in the choice of an endpoint identity
    realm, including the use of existing addresses as an identity tokens,
    the use of distinguished (possibly non-routeable) addresses as
    tokens, or the use of tokens drawn from a different realm (such as
    use of a fully qualified domain name).

    Shim6 uses the first of these options, and the endpoint identity for
    a host is one of the locator addresses that are normally associated
    with the host.  The particular locator address selected to be the
    endpoint identity (or ULID) is specified in [RFC3484].  Shim6 does
    not mandate the use of distinguished addresses as identities,
    although the use non-routeable distinguished addresses in this
    context is described as an option in this approach.

-- 
Crist J. Clark                               crist.clark at globalstar.com
Globalstar Communications                                (408) 933-4387