Re: "from the real world" - typical multihoming discussion

[Sean Doran <smd@ebone.net>]

Masataka Ohta <mohta@necom830.hpcl.titech.ac.jp> writes:

> It will be great if small operators do not have to use BGP merely
> because they are multihomed.

Yes, agreed.

At the risk of summoning down fire from heaven, I would
like to point out that NAT makes this sort of multihoming
possible, and despite the often-alleged huge cost of NAT,
some sites consider it easier to manage than BGP,
particularly when it comes to managing the attraction of
return traffic from sources across the Internet.

This is in large part because in general, BGP: is
_difficult_; and is necessary to use merely because one is
multihomed.

One goal of the post-CIDR v6 IDR should clearly be to make
multihoming maximally simple, on the assumption that:

        a/ nearly _everyone_ will want to do it & may have
           the opportunity in the future

        b/ multihoming may happen for reasons of:
                i/   redundancy
                ii/  volume management (load balancing)
                iii/ performance management (use provider
                        X as a return path from some places;
                        use provider Y as an outgoing path
                        towards some places, and so on)
                iv/  price management ("10+ dialling equivlanet")

CIDR does not make any of (b) easy or inexpensive, and 
(a) will cause global routing to explode in the absence of 
magical network renumbering technology.

        Sean.