From the discussion on draft comments, I have the following basic
question:
Is a value A is assigned to either the EID space or the RLOC space?
Could site X have an EID with value A while site Y (or
even a non-LISP) has an RLOC (or globally routable address) with the
same value A?
Architecturally, yes, the value A can be an EID and an RLOC. In
practice, no, for IPv4 and maybe for IPv6. Let me explain.
Since there are two namespaces for each of IPv4 and IPv6, it means,
for the case of IPv4, there are two 2^^32 number assignment spaces.
But we don't have two allocation authorities, one for each, so the
addresses will be assigned from one 2^^32 pool and be used as either
an EID or an RLOC depending if the site has converted to being a LISP
site.
For IPv6, if we had a PI allocation authority, then it would hand out
EID prefixes to end sites. If we also had a PA allocation authority,
then it would hand out RLOC addresses to infrastructure providers. In
this case, if the two authorities acted independently, then the same
value could be assigned for each namespace.
This is not a problem to duplicate the address in each namespace. But
I do believe for operational sanity it would be nice to look at logs,
debugs, or whatever, see an address and decipher it is an EID versus
an RLOC. This is one of the reasons the working group wants to request
an IANA assigned /12 or /16 (not decided yet I think).
For instance, consider deploying an IPv4 LISP site now. Could one
take an IPv4 prefix already used
globally by a different company/site - and use it for my new LISP site
as an EID prefix?
No because there is one allocation authority and it is enforcing a
unique address allocation policy.
Do all the drafts always check for the IP address in the mapping
database to see if it is an EID? I recall seeing some
cases of checking the global routing table - but that could be bad
memory at this point.
If you look in the ALT routing table and find a prefix, it is an EID.
That is an example of looking in *a routing table*. But that is part
of the mapping database system. So it is one in the same.
Could a host in a LISP site send to an IP address as an EID and the
same IP address as a globally addressable (or routable)?
A host sends to destinations. So it doesn't know one from the other (a
feature). So yes, both a non-LISP site host and a LISP site host can
talk to both a non-LISP site and LISP site destination.
I am confused because "architecturally" I believe the EID space and
the RLOC space are separate namespaces - but in practice
in the drafts, it seems that a given value must belong to a single
entity, whether it is used as an EID, globally addressable, or both.
That is what you get when you build an architecture after the network
is built. ;-)
Dino
Is this clearly specified anywhere? What am I missing?
Alia
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