On Fri, 31 May 2019 00:10:42 -0000, Mel Beckman said:
What are you talking about? Do you use multi homed BGP? If so, I’d expect you to know that an organization with multiple sites having their own Internet still uses a single AS. They have IGP paths to route traffic between sites (e.g., by using dedicated circuits).
The situation being discussed is an organization with multiple sites that *don't* have a behind-the-scenes dedicated circuit, tunnel, or other interconnect. For example, XYZ Corp has a POP in Tokyo announcing a /16 to their provider there, and a POP in DC announcing a different /16 to their North American provider, using the same ASN for both - but traffic between the two /16s traverses the commodity Internet. Or they advertise the same /16 and pray to the anycast gods. :) (Actually, that's OK too, as long as both Tokyo and DC also announce a second route (possibly a more-specific, or different address space) for their interconnect needs)