On Fri, 22 Aug 2003 15:15:34 -0700 "Tony Hain" <[EMAIL PROTECTED]> wrote:
> Keith Moore wrote: > > > > > Expecting the network to be globally > > > > > accessable and flat is not reality. > > > > > > > > the network has never been flat in reality, but part of the > > > > purpose of IP has always been to provide the illusion of a > > > > flat network. > > > > > > That would be the purpose of the illusionary session layer ... > > > > uh, no. that's what layer 3 is for. you have heard of routing? > > Yes I have heard of routing. Its job is to deliver the packets between the > current attachment points. There is no requirement for L3 to maintain a > consistent flat perspective up to the app. L3 makes routing look flat to the end systems. That's its job - to steer packets through the network. The network is aware of topology so that end systems don't have to be. Of course the original design of IP routing expected end systems to be more-or-less fixed relative to the network. It's true that mobile/nomadic systems aren't well-served by traditional IP routing. That's why people are working on mobile IP. It's also true that ad hoc networks aren't well served by traditional IP routing mechanisms. Still, these are properly L3 functionality, even if they're not well served by existing mechanisms. > That only happens because the app > has the illusion of a stable session identifier that it derived from L3 > information that was valid at one point in time. The design of both IPv4 and IPv6 uses addresses as both endpoint identifiers (hence their use in TCP) and locators. This was (and still IMHO is) a reasonable compromise for hosts with fixed locations. For mobile or nomadic hosts you need to seperate them somehow. > > ... > > it's not the existence of v6 LL addresses that causes the > > problems, it's the idea that they're suitable for general purpose use. > > ... > > > Refusing to allow them to be used only > > > ensures that app doesn't work without explicit manual intervention. > > > > nobody has suggested refusing to allow them to be used - > > Please get the story straight here. In that last comment they can be used, > but the prior one precludes them from being used. I don't know why you can't see the difference. Why don't you go back and read those two sentences over again and again until you get it? > As I see it, in the absense of any other address, there is no choice so > every app must have the option to use them. If there are no other address available, the network is dysfunctional. This might be an acceptable condition for a test bench, say, or while debugging a network that is broken, or to support a few very specific apps. It's not an acceptable condition for normal operation. > With other options available, > the app should have the opportunity to decide which it wants to use based on > it operational characteristics and goals. Either way the app needs a flag to > indicate what it is dealing with. I'll certainly agree that as long as v6LL's exist, it's important to be able to distinguish them from real addresses. But this doesn't make them suitable for general use. Keith -------------------------------------------------------------------- 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] --------------------------------------------------------------------
