Re: Private ASN suppression

[Danny McPherson <danny () tcb net>]

In short, see RFC 2270.  

Some of the primary differences are that several of the 
BGP attributes are preserved with confederations, versus
that autonomous "look and feel" provided by dedicated ASs,
not to mention that any such model would assume that the 
providers employ confederations as well.  Also, managing
it would be a nightmare.  

More importantly though, is that if providers allow customers
to maintain sub-ASs of a confederation they're placing a 
considerable amount of trust in the capabilites of those 
customers, and errors on the customers part could impact
much more than just the customers part.

-danny

> I'm trying to understand the problem being solved by the Cisco 
> private AS removal feature.  In particular, what advantages does it 
> offer over confederations, which would seem to do the same thing when 
> externally advertising customer routes?  Is there a performance 
> benefit?
>
> RFC1998-style multihoming with a private AS is a possible 
> application, I suppose, for any routes that are NOT marked with 
> NO-EXPORT.