[nsp] Methods for Non-BGP multihoming

Alex Nguyen anguyen@videotron.net
Tue, 23 Jul 2002 21:34:12 -0400 (EDT)

On Tue, 23 Jul 2002 CARL.P.HIRSCH@sargentlundy.com wrote:
> If both ISPs were to advertise our /16 address space (registered by us, not
> an ISP), we wouldn't necessarily need an AS number, would we? Given that we
> wouldn't be actually talking BGP with anybody and the ISPs would be
> handling the route advertisements.  We'd put a metric on our static routes
> outbound so only one link would be used unless it failed.
> Are there any serious gotchas to this sort of approach? Outbound routing
> would be very simple, but I'm wondering about the logistics of having ISP A
> and ISP B both advertising routes. When traffic comes inbound to our
> network, is there any way to make sure that one provider is always used?
> Does it even matter? It's the issue of how traffic finds its way to your
> network when you're multihomed that I'm not quite clear on.

This configuration make your route inconsistent in the routing table since
the /16 will have 2 origins ASN. I'm not sure yours providers allow you to
do that.