> Given a list of addresses for a target, how would an application pick > one that is assured to work at the receiver? Answer: it can't without > knowing the topology. The only way to keep the app from knowing > topology, and make the app work in the presence of a list is to pass the > label that was used to get the initial list, so the receiver can get its > own that is topologically appropriate. Tony, What you are essentially claiming is that an application that doesn't know about network topology should defer choices that must be based on topology to some other application. Of course, it's not any easier for that other application to know about topology, and it's also less reliable and less efficient. It might seem reasonable to isolate the topology-selection stuff into a single application, but it's not - different applications have different needs in this regard. Again this is from experience with an app that needed to choose the closest of several alternate URLs for a resource - doing all of the DNS lookups on all of the URLs and then trying to find the closest one of those was just too slow. Finally, if you want any app - even this "special" app, to be aware of topology, then the first thing you need is globally scoped labels for points in the topology - which is exactly what exposing site locals to applications denies you. Keith