Subject: Re: [lisp] LISP and IPv6

From: [email-masked] (Noel Chiappa)
Date: Mon, 23 May 2011 15:55:35 -0400 (EDT)

> From: "Templin, Fred L" <[email-masked]>

    > I am skeptical that a large site such as a major enterprise network
    > that participates in BGP routing on its own behalf would do better
    > to use LISP than to just use native IPv6.

I just gave you _an_ example of something LISP could do which the current
routing architecture cannot; there are many more.

I cannot conclusively show that for _every_ IPv6 site, LISP will have a
positive cost/benefit ratio, since I have no way of knowing the costs and
benefits for each and every site. That's a decision they will all have to
make for themselves.

And speaking of benefits, you totally blew past the "addition of a
fundamental new architectural capability like separation of location and
identity" (to IPv4 and IPv4 alike). This may not mean much to you, in
which case I don't see that there is much else to be said.

    > We have also talked at length in the past about "identitiy". The
    > LISP "identity" is an IP address, and IP addresses name interfaces
    > not end systems.

i) This is a wholly different point to 'what is the value of LISP to IPv6
users'.

ii) As you note, this point was made years ago, and it was discussed at
length then, during which discussion it was pointed out that taking as the
LEID the address of an internal 'virtual' interface provides something
that is the _functional_ equivalent of an EID: totally location
independent, names an entire stack, etc, etc.

Other than the 'angels on the head of a pin' question of _what_ exactly is
being named (and I'm prepared to argue that _functionally_, a virtual
interface _is_ basically an endpoint), how does such an LEID differ from
the classic EID as I defined it in:

  http://www.chiappa.net/~jnc/tech/endpoints.txt

For example, exactly which of the 'desirable' attributes listed in Section
9.1, other than those which IPv4 addresses inherently _cannot_ exhibit
(e.g. local creatability), do such LEIDs not possess?

If it's not a more exact match, that's because without changing the entire
host stack, including the transport layers, it's impossible to introduce a
true 'endpoint name' (or endpoint names with characteristics that IPv4
addresses cannot meet) to the existing IPvN architecture.

Since nobody appointed me Internet Czar, with the power to change all
hosts everywhere, a 'true' EID seems currently out of reach; so we do what
we can - which in the case of LISP is 'pretty good'.

	Noel

---

From: "Templin, Fred L" <[email-masked]>
Date: Mon, 23 May 2011 13:39:35 -0700

Hi Noel, 

> -----Original Message-----
> From: Noel Chiappa [mailto:[email-masked]] 
> Sent: Monday, May 23, 2011 12:56 PM
> To: [email-masked]
> Cc: [email-masked]
> Subject: RE: [lisp] LISP and IPv6
> 

Inbound traffic engineering is what I seem to be
hearing about the most, and I agree that it is an
interesting point to consider but I'm not entirely
sold on it. Can you say more about "many more"?

> benefits for each and every site. That's a decision they will 

Is there some way to provide an unambiguous guidance
to site adminstrators whereby they can make an informed
decision?

> which case I don't see that there is much else to be said.

I like fundamental new architectures - I have documented
several of them based on tunneling myself. The concept
of separation of inner and outer IP addressing is the
same as what I have documented whether/not you call
it "location/identity".

> i) This is a wholly different point to 'what is the value of 

Agreed.

> independent, names an entire stack, etc, etc.

I think I was either the first or one of the first during
those discussion to suggest placing an address on a
loopback interface. The address could also be placed on
some other form of internal virtual interface such as a
tunnel interface. The address therefore names the internal
virual interface, but the end system may have multiple of
those - each associated with a different stack.

> (e.g. local creatability), do such LEIDs not possess?

I'm not going to argue about your document, but as I
said there may be multiple internal virtual interfaces;
each with its own (pseudo)identifier. But, the end
system still has a single *identity* which is not
fully captured by any one of the address-to-loopback
assignments.

> addresses cannot meet) to the existing IPvN architecture.

HIP has something that closely resembles a true endpoint
identifier.

> we can - which in the case of LISP is 'pretty good'.

Without changing all hosts, however, LISP can only
reach in as far as the site border router. In that
case, the "EID" is a prefix that names a network;
not an address that names an end system interface.

Fred
[email-masked]