> 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.
I don't object to that. I do object to treating LL as if they were generally applicable, or expecting apps to be able to use them and saying that networks don't need portable addresses. > > > 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.?.?. You have a strange notion of capability. You seem to want to claim that a less functional and less predictable network, one that supports fewer apps and imposes more constraints on those it does support, has more capability. > > > 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. Nope. Expecting apps to use scoped addresses constraints the kinds of apps we can run. > > 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. I certainly acknowledge the existence of such devices; I have one on my desk. And I don't claim that it's easy to deal with having multiple interfaces. But having scoped addresses only makes the problem worse. Nor do the flags help an app sort out which is appropriate to use. So by all means let's try to solve the problem of hosts with multiple interfaces, but let's not try to make our task even more difficult by insisting that apps support ambiguous addresses or addresses with inherently limited reachability. > > > 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 say that it's okay for the network to impose a version of "reality" that doesn't adequately support apps. > > 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. Or they want to make the network so unpredictable that the market for apps is fragmented - some apps can work in one kind of network, some in another. Look - the whole idea of IP is that the apps don't concern themselves with routing, and the network doesn't concern itself with data. trying to take away this separation of function doesn't make the network more flexible, it makes it less flexible. And it doesn't allow the network to support more apps, it reduces the number of apps that the network can support. It balkanizes the network. > > 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. You're trying to cast the most important design feature of the Internet as a technology restriction. Forgive me if I'm not sympathetic. -------------------------------------------------------------------- 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] --------------------------------------------------------------------
