Subject: Re: [rrg] Next topic: properties of identifiers

From: [email-masked]
Date: Sun, 12 Jul 2009 04:14:28 EDT

In einer eMail vom 12.07.2009 01:47:45 Westeuropäische Normalzeit schreibt  
[email-masked]:

Heiner  -

How would map-and-encap schemes be incrementally deployable if  they
didn't use IP addresses for both address realms?  Even  translation-based
schemes need IP addresses as locators for backwards  compatibility.

- Christian

Let's put it differently: Incremental deployability requires still BGP  to 
overcome the main function of BGP which is the non-scalable way to  
disseminate all these hundred thousands of prefixes.
The methods are not new: Remember  BGP-based dissemination of MPLS-VPN  
sites (just lacking the goal to build ONE SINGLE "internet-VPN") : here the  
information are labels, i.e. not IP addresses. Also remember LISP's default  
mapper. Issueing a prefix of length 0 might attract traffic destined  for a 
node which doesn't propagate its traditional reachability prefixes anymore  
but just new routing info for a new architecture, analogously to the  
MPLS-labels.
 
Heiner

On Jul 11, 2009, [email-masked] wrote:

> Sorry  Christian that I have a different opinion. At first, a locator,
> i.e. a  location information, must be routable (aggregatable is  
>  something
> completely different) and, of course, it must be written  somewhere,  
> e.g.
> into the field for destination IP  address,   and/or destination
> MAC-address and eventually,  for some transitional time, into a new
> additional header. Even LISP  authors emphasized that the locator
> addresses inside the LISP header  could potentially make up a new
> namespace. However it is the LISP  supporters' decision to use
> non-routable IP addresses instead, or  better said, the same
> IP-address-based routing technique which  produced and produces the
> scalability problem.
>
>  Heiner

---

From: Christian Vogt <[email-masked]>
Date: Tue, 14 Jul 2009 10:45:49 -0700

On Jul 12, 2009, [email-masked] wrote:

> Let's put it differently: Incremental deployability requires still BGP
> to overcome the main function of BGP which is the non-scalable way to
> disseminate all these hundred thousands of prefixes. The methods are  
> not
> new: Remember  BGP-based dissemination of MPLS-VPN sites (just lacking
> the goal to build ONE SINGLE "internet-VPN") : here the information  
> are
> labels, i.e. not IP addresses. Also remember LISP's default mapper.
> Issueing a prefix of length 0 might attract traffic destined for a  
> node
> which doesn't propagate its traditional reachability prefixes anymore

Heiner -

I agree with the argument that IP addresses could theoretically be
replaced in their role of locators.  Although I would add that the
feasibility of this heavily depends on the deployment model:

LISP proxies are not a good example because they require IP addresses
as locators to route packets towards a proxy.  On the other hand, APT's
deployment model -- which calls for initial local deployment and
subsequent expansion -- could facilitate the introduction of new
locators.  Of course, those new locators would have to be suitable for
use across administratively discontinuous providers, like IP addresses.

- Christian