It is undesirable for a large enterprise to use a multi-address/host based
solution without a mechanism to interact with the network topology to
perform path selection. Network operators know more about the viability
of paths (whether by technology or manual policy) than the hosts do.
Left-side longest-match is hardly a sufficient routing protocol and/or
policy control for a multi-provider topology like the Internet. The
network *MUST* be a part of the solution -- enterprises want policy
control, and policy control should be centralized.
Succinctly put. However I don't think size matters as much as does the
existence of policy. Only the hardware/software/wetware at the edge of the
enterprise is likely have the necessary information to enable rational path
(and, therefore, source and destination address) selection.