Thus spake "Keith Moore" <[EMAIL PROTECTED]> > > Some applications MAY prefer one address over another, but most > > applications will not care. IMHO the best solution is to allow the OS > > (and therefore presumably the admin) to specify a default policy, but let > > applications provide "hints" to the OS that other addresses may be > > better in certain circumstances. > > no, that's ridiculous. applications need a stable API that works the > same from one platform to another, not one that changes at the whim of > some network administrator. and we don't need an API that only works > for "most applications".
The API itself will be stable, it's only the returned value(s) that may change based on exactly where a host lives and how it's configured. There is no way for software alone to determine many of the variables involved in address selection, especially things like security policies. As long as the API returns _something_ usable, it can be considered stable. > > I'm not convinced that such an API is immediately useful, however, > > since it seems to assume a prior means of determining which addresses > > will work at all. Most applications will be faced with a scenario where > > the source has N addresses, the destination has M addresses, and it > > won't be clear which of the N*M combinations will work without > > testing them all. > > you're absolutely right about this part. about the only thing the API > can reasonably do is let the application specify whether it can use a > temporary "privacy" address (as in a web browser) or whether it needs a > public address (as in a server or p2p app). That argument is loaded with flawed assumptions. There are many servers and p2p usage scenarios that would be served just fine by local addresses. For instance, some admins may prefer intra-company communication use local addresses even if global addresses are available, while other admins may prefer the opposite. You won't get far ignoring the "whims" of the person who owns all of the hosts in question. The application writer can't possibly anticipate all ways his code will end up being used, which is why I believe that a per-host policy (hidden behind an API) is the best way to go. > it is, and always has been, completely unreasonable to expect either > hosts or apps to have to choose between a number of > (source,destination) address pairs in order to successfully connect > with other hosts. no API can solve that problem. Not true; it would be fairly trivial to implement an API function that tests all N*M pairs and return the set of pairs which appear to work. This would then be fed into a different API function to determine the "best" pair for the application's needs. S Stephen Sprunk "Stupid people surround themselves with smart CCIE #3723 people. Smart people surround themselves with K5SSS smart people who disagree with them." --Aaron Sorkin -------------------------------------------------------------------- IETF IPv6 working group mailing list [EMAIL PROTECTED] Administrative Requests: https://www1.ietf.org/mailman/listinfo/ipv6 --------------------------------------------------------------------
