Keith Moore wrote: > > Yet you want to ban apps from recognizing the defined flags FE80, > > FEC0, FC00, ... > > more precisely, I want to discourage the expectation that > apps can make > do with *just* these. and if apps have more portable addresses > available to them, why should apps deal with these at all?
Some apps should simply ignore them. Some apps would like to leverage them to solve problems that are not possible when limited to a single globally reachable address. > ... > > > applications should be able to forward addresses to other > > > hosts; this is an essential capability. that doesn't mean > > > that they can expect those addresses to be usable from remote > > > locations. but if they're not usable, the reason should be > > > either network failure or administrative prohibition - in > > > other words, something that the app should not be expected to > > > work around. > > > > So there should only be a single address per host, or all addresses > > must have exactly the same policy and reachability > characteristics??? > > more or less. I'm still trying to formulate a precise > statement of this that accomodates renumbering, multihoming, > local addressing, ad hoc networks, etc. In other words we should not allow IPv6 to have any more capability than IPv4 with more bits.?.?. > > > This is the limitation of the IPv4 world. > > it's not a limitation, it's a feature. Ok, call it a feature, but it is one that we need to leave behind because it constrains the kinds of problems we can solve. > and while it was > never mandated in the v4 world, having multiple interfaces > per host turned out to cause problems when it mattered which > address you used, so people tended to avoid doing so except > in special cases. Look around, those special cases are becoming the norm. Portable devices have multiple different interface types, and the reachability characteristics of those interfaces is very different. By insisting on a flat space, you preclude the ability to have the flags above available to sort out which interfaces might be appropriate for which uses. > > > There is nothing preventing > > an app from continuing down that path. Unfortunately there are some > > who want to preclude anyone else from taking a different path. > > some people don't want a predictable environment for > applications; No, they want a predictable way for apps to deal with the reality of the underlying network. > or they want to limit the kinds of apps that > can be supported. No, they want to expand the kind of apps to include those that are not possible with a monolithic view of the world. > one could conclude that they want to harm > the ability of the Internet to support new apps, or to reduce > the size of the market for new apps. I prefer to think of > them as just naive and/or obtuse. One could also conclude that IPv6 won't reach its full potential until a new generation of app developers are free to explore the space beyond the boundaries of 20 year old technology restrictions. Tony -------------------------------------------------------------------- IETF IPng Working Group Mailing List IPng Home Page: http://playground.sun.com/ipng FTP archive: ftp://playground.sun.com/pub/ipng Direct all administrative requests to [EMAIL PROTECTED] --------------------------------------------------------------------
