On Wed, 2003-03-26 at 16:38, Tony Hain wrote: > Ted Hardie wrote: > > I think you may underestimate how much trouble this might cause in > > applications. > > As Dave Crocker noted in response to Margaret Wasserman's > > presentation to the APPs Open Area meeting, applications have > > been designed so that > > they > > do not know and don't need to know anything about network > > topology. > > If you > > require applications to understand the consequences of different > > unicast address > > scopes, you are changing a pretty fundamental assumption. > > While it is > > theoretically > > possible to change that assumption, it is a major piece of > > work, and I > > believe that > > the "sense of the room" was that the advantages of Site Local > > were not > > worth that > > amount of work. > > I am not arguing that every app need to know about topology. If this is > such a big deal, we should simply fix the API so that by default it only > returns global scope addresses, then add a new function for those apps > that are interested in the limited scope. This doesn't sound like rocket > science, and the arguments against it are coming across like 'we don't > want to change because it is too much work'. Rather than argue that > nobody can ever use a new feature, the basic approach should be that you > don't have to unless you want to. > Its not that 'we don't want to change because its to much work'. Its that the Internet architecture assured us that the hour glass model applied, that the network topology would remain abstracted within what to us is an opaque address space. One of the number one reasons its so easy for new application layer technologies to be deployed is that a developer doesn't need to know or care about any layer below TCP (or, in rare cases, UDP). If the lower layers want to change that hour glass model then we're talking about a serious breach of contract with the layers above it and a dangerous blow to the hour glass model. -MM