If the old provider is advertising the prefix based on your advertisement to them (you're running BGP), then their advertisement should cease shortly after your link to them goes down. Likewise, the new provider would only propagate the advertisement after you advertise it to them. Michael H. Michael Smith, Jr. Network Services and Security Manager Clark Atlanta University -----Original Message----- From: owner-nanog@merit.edu [mailto:owner-nanog@merit.edu] On Behalf Of Mike Donahue Sent: Monday, August 04, 2003 2:22 PM To: 'nanog@merit.edu' Subject: AS announcement question (easy) Hi, sorry for this low-level question, but at least I'm not posting in html. :) My company owns a class C, and we're switching ISPs. The "new" provider is telling us that they can start announcing, without us having to tell the old provider to stop announcing. I.e., a 2-3 day period where both are announcing our class C. This conflicts with my extremely (admittedly)limited knowledge. Can someone let me know if this is OK/not OK? Thanks in advance, Mike Michael Donahue WATG (949) 574-8500 x261