We currently have a routable block (class B) of IP addresses. We are in the process of designing a disaster recovery site. Our main site is already dual homed to two different Internet service providers via BGP. A consultant told us that in order to allow us to test access to the DR site without affecting the production environment, we should get another block of addresses from ARIN and advertise those addresses out the DR site's Internet connection. Can we even expect to get another block from ARIN if we already have a class B, and could we not accomplish the same thing by advertising a subnet of our existing Class B at the DR site? I would actually prefer to advertise a subnet of our class B, but am wondering if there are any reasons why this is not a good idea. Also, I have seen reference to some Internet service providers possibly not accepting /24 BGP routes and either dropping them or aggregating them to a /21 or /20 or /19. Are there recommendations as to what is the longest prefix that we should advertise to guarantee that the prefix will be advertised throughout the Internet? Chris