One way to do this is for two ISPs to band together
in order that each ISP can sell half of a joint
multihoming service. Each ISP would set aside a
subset of their IP address space to be used by many
such multihomed customers. Each ISP would announce
the subset from their neighbor's space which means
that there would be two new DFZ prefixes to cover
many multihomed customers.
Each multihomed customer would run BGP using a private
AS number selected from a joint numbering plan. This
facilitates failover if one circuit goes down but
doesn't consume unneccesary public resources per customer.
[...]
