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Re: why not AS number based prefixes aggregation

  • From: Benson Schliesser
  • Date: Mon Sep 08 16:16:59 2008

On Mon, September 8, 2008 09:46, Scott Brim wrote:
> Also, ASNs are not
> aggregatable so we can't use them to represent a large number of
> independently routed networks.

Scott,

I'm not sure an Autonomous System would want to be aggregated. By its
nature it is capable of having arbitrary connectivity. On the other hand,
addresses can be aggregated. An ASN-based address system would support a
more efficient form of aggregation than we have today. And routing
(including TE) could be supported by attributes, rather than by
address/prefix-len. *shrug*

Yang,

As somebody pointed out already, LISP provides approximately the same sort
of mechanism. Though it uses a list of Locators (backbone/core IP
addresses) rather than ASNs to identify an Endpoint's site, relying on a
lightweight form of tunneling through the core to support endpoint
communication. This allows it to preserve both IPv4/v6 and existing global
routing protocols (and thus deployed support). The downside is that it
requires a more dynamic mapping mechanism than a theoretical ASN-based
approach. You can learn more at http://www.lisp4.net/, and discuss it on
the [email protected] mailing list.

Cheers,
-Benson