Re: Transport level multihoming

[Geoff Huston <gih@telstra.net>]

>If the transport pushes multihoming to the end node and IP layer
>multihoming not being propagated beyond direct peers, it would seem that
>such a system could significantly further the scalability of the Internet,
>while increasing the level of flexibility of multihoming (i.e. if the
>transport allows adding address to a connection in progress, this would
>facilitate mobility, and other benifits).

The bgp table has a number of roles:

- connectivity maintenance
- policy negotiation
- destination-influenced inter-domain traffic engineering

While the push to the end system for multi-homing control can allow some 
degree of benefit in the number of prefixes used to maintain connectivity 
of the inter-domain space, it complicates policy negotiation as we know it 
today, and it certainly alters what we currently think of as inter-domain 
traffic engineering. The issue is that inter-domain traffic engineering and 
policy assertion will not go away - if it is no longer possible to use 
announcements of AS + specific routes to achieve these two objectives, then 
doubtless other mechanisms will be found. Now if you regard the total 
inter-domain routing space as an information negotiation across all three 
spaces, the real question in my mind is whether this approach reduces the 
total amount of information sloshing around the inter-domain space or not? 
Somehow I'm not convinced that this allows a real information reduction.

Geoff